US2932003A - Electronic cycle computer - Google Patents

Description

April 5, 1960 J. l.. BARKER ELECTRONIC CYCLE COMPUTER 5 Sheets-Sheet 1 Filed Sept. 21. 1954 April 5, 1960 J. L.. BARKl-:R

ELECTRONIC CYCLE COMPUTER NERE 5 Sheets-Sheet 2 m .Sk m. .Sl m

April 5, 1960 J. L. BARKl-:R

ELECTRONIC CYCLE COMPUTER 5 Sheets-Sheet 5 Filed Sept. 21, 1954 April 5, 1960. L. BARKER ELECTRONIC cYcLE: COMPUTER da@ ATTORNEY April 5, 1960 J. L. BARKER ELECTRONIC CYCLE COMPUTER 5 Sheets-Sheet 5 Filed Sept. 21. 1954 a s E um@ E msm.

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ATTORNEY nited States Patent O faice ELECTRONIC CYCLE COMPUTER John L. Barker, Norwalk, Conn., assignor to Eastern Industries, Incorporated, East Norwalk, Conn., a corporation of Delaware Application September 21, 1954, Serial No. 457,437

27 Claims. (Cl. 340-41) This invention relates to an electronic circuit for accepting input impulses of variable time length' and variable time spacing, and for controlling the actuation of one of a plurality of utilization devices selectively in 'accordance with measures of the density of the received pulses with respect to time. More particularly, the invention relates to an electronic system for the control of vehicular or comparable types of traffic wherein it is desired to control the ultimate rate of ow of the traffic in accordance with, and proportionally to, the average rate at which such traffic is presented to traic-detecting devices.

Heretofore, a v-ariety of devices have been proposed to facilitate the ow of traic along highways, particularly those that pass through congested areas in which it is necessary periodically to provide for right-of-way for vehicles on side streets and at highway intersections. For example, in my Patent No. 2,288,601, issued July 7, 1942, there is disclosed an integrated trafiic control system whereby one or more traic lights arranged at intersections may be controlled to function in any of a variety of different timing periods in accordance with the volume of traflic flowing on the highway. As outlined in this patent, it has been found that more efficient use of existing highway facilities can readilybe obtained by varying the light-timing cycle controlling the traic itself. For example, if the traffic on the main road is relatively light, the trafc lights at each intersection may be placed under the control of associated local controllers which may be of the full or semi-traffic-actuated type in which the transfer of right-of-way to one road from another to initiate a right-of-way signal is made responsive to traflic `actuation of a traiiic detector in such one road, or may be of such other type of local control as may be desirable. As traic increases, however, it is necessary to place the individual intersection controllers under a coordinated master control system whereby traflic lights at successive intersections may be operated in accordance with an overall plan to provide the most eicient use of the highway. To this end it is essential that the master control system provide a variety of differently timed cycles of operation for th-e several intersection controllers. In each instance, the timing cycle selected is one to provide Vfor the freest possible flow of traliic on the main highway in accordance with the density of traic known to exist on such highway and, at the same time, to avoid undue interference with the movement of side road traic that is attempting to cross or enter the highway.

In the arrangement of the master controller disclosed in the above-mentioned patent, the density of the traiic on the main highway is determined over pre-established sampling periods, preferably of six-minute duration, and

the master controller timing cycles are actuated in accoi-.dance with the density observed during suchperiods. Specifically, the apparatus includes a trafc signal cycle selecting apparatus for control of a master controller for a seriesof individual intersection traiiic signalvcontrollers 2,932,003 Patented Apr. 5, 1960 along a road and having a number of different traic signal cycles including one minimum cycle providing independent control of the individual controllers responsive only to traic'actuation of a traic detector at the individual intersections, a number of other cycles of successively longer time lengths providing coordinated control of the several individual controllers to have accord of right-ofway proceed progressively along the road at successively lower traic speeds, and a cycle of maximum length providing synchronized coordinated control of the individual controllers for substantially simultaneous accord of right of way. The cycle-selecting apparatus, when operating in any given cycle, is controlled by a vehicle-counting device to maintain the existing cycle in the event the density of traic on the highway remains unchanged or to shift to a higher or lower'cycle, respectively, depending upon an increase or decrease in vehicle traic on the highway. l

The basic concepts of the traffic control devices disclosed in the patent have proved extremely useful in most cases of highway traflic control and are embodied in many control systems in current use. However, the substantial increases in operating speeds of vehicles and in the numbers of vehicles using our highways during recent years have imposed limitations on the use of the relay circuits disclosed in the patent. Furthermore, although the effectiveness of such systems can be improved by increasing the number of detectors used to determine the volume of traflic owing on a highway, it has been found that an increase in the number of vehicle-counting devices imposes a further load on the relay circuits of the patent. In addition, at the time the patented structure was developed, it was believed that in the general application of traliic control it could be assumed that traffic volume would increase or decrease gradually over any given period and that the concept of step-by-step changes in traic light cycling was the most effective method of control for most instances. However, it has been found that the use of progressive changes to'step through successive cycles to eflzect faster or slower movement of traffic is not the most practical method under all operating conditions. For example, if it be assumed that the traflic light system inthe vicinity of a large industrial plant is operating at its lowest cycle immediately prior to quitting time, a progression of live cycling periods would be required before the system could be raised to its highest or most effective operating cycle. If the system employed a six-minute sampling period, such a procedure would require 30 minutes to complete. Obviously, this type of control does not provide for the most efficient use of the road adjacent the plant during the periods of the day that a large number of employees are arriving or leaving by car. Finally, traictstudies have shown that'traflic patterns for a given locality vary as a result of many constantly changing factors and that the several change over points at which the master controller effects selection of the several operating cycles should be capable of Vrapid and convenient adjustment to permit a traffic engineer or operator to adapt the system to any set of conditions that assapos f l In addition the output of this counting circuit is employed to provide a Vdivided or proportionately reduced constant pulse unit output that is fed into separate integrating circuits whereby it is possible to obtain aninstantan'eous measure and indication of the traffic passing a given point or points over a relatively `short period of time, as well as to obtain an average traic density measurer'n'ent and indication yover alonger period 'of time which may be employed Aas a sampling period. Both of such measures may be indicated selectively for the immediate guidance of the traffic engineer operating the system, whereas the average density measurement is employed jdirectly to effect the selection vof successive operating leads of the master traffic 'controller and may be employed to actuate a `recording device whereby the information relating to trafiic densities may beA stored for future study. l Finally, the output of the average density-measuring circuit is applied to a cycle computer network thatis eliectiye to select the proper Ioperating cycle on which the 'traffic signals should be functioning in accordance with the density of traffic then being detected: l

Although in some respects the t'er'ms traiiic density" and trarne volume are round in the Y'art tonlraye ditjferent meanings as the number of `yehicl es p cr `unit distanc'e along a road and 'as the number of vehicles 'passing a given point per unit of time respectively as indicated for example at pages 477 and 481 'in the Trafiic Engineering Handbook, vsecond edition, published 1950 by the Institute of Trafiic Engineers, these two terms are Jused interchangeably in the present application as re- 'ferring generally to the number of vehicles passing a given point per unit time at `one or more locations as the case may vbe in the context. vIn general, the invention provides a trafiic integrating control circuit in which traffic counts may be detected A'at various points on highways or feeder lanes, thatis detectorsmay be placed in vindividual lanes of a highway or in feeder lanes. The circuit of this invention totalizes the information received from the various detectors, and in accordance with predetermined conditions set in the circuit bythe operator, actuates the different output circuits. Preferably these various output circuits control tratric mechanisms, such as synchronized traic controllers which may be so adapted Aas to vary the synchronization of the lines in accordance with the density 'ofthe traiiic onthe routes being analyzed.

An example of this operation would be 'a system *in which the traffic controlled mechanisms would be adapted to provide different cycles of operation Von 'a series of synchronized traffic lines according to the load upon the lanes of a main highway plus those of 'an important feed'- erroad. A particular advantage of this Vinvention is that 'it provides for switching from one to another of its output control circuits actuating the traic control mech- `-anism's; in any sequence and thus avoids the delay often encountered in ,the former` step-wise switching devices vof the prior art. This is particularly important lin any cir- :cumstances where peak `loads occur suddenly such as at quitting time in a large industrial plant.

Additionally, this invention provides circuits which 'enable the master controlling system to change from one to another of the alternative tratlic control circuits substantially within a single sampling period when peak loads occur without yencountering the usual time period delay often found in devices of this character.

Incorporated in the circuit of this invention are conltrols enabling the unit to have greater iiexibility than has previously been found in such circuits. Contributing tosuch iiexibility is the ability of the circuit'selectively to detect one through four lanes of trafiic and to compensate the parameters of the circuit accordingly when the number of detectors is varied. It allows for control of the various traiiic actuating mechanisms Yin accordance with tratiic densities which may be present `by the operator and additionally allows for the switching from one t'raic actuating circuit to another at different trafic density percentages depending on whether the load is increasing or decreasing. This ability to control the transfer points individually provides for not only greater flexibility but a more efiicient degree of control and wider permissive variations.

The principal object of this invention is to improve the flexibility and response time characteristics of traiicactuated control systems. A further object is to increase the accuracy of the determination of densities of traine and their respective assignment to provide trafiic signal cycles.

A further object is to increase the acceptable total variation over which traic from the sampling detectors may be made to occupy the total selected range. A further object is to simplify the adjustment of the system and the interpretation of the results provided by the system bythe provision 'of linear adjusting dials andfindi eating scales.

These and other objects are attained, in aprefe'rred form ofthe invention, 'as shown in the appended 'draw- `i'ngs, in which: y Fig. 1 is va block 4diagram of the several components offtheinv'e'ntion;

Fig. 2 is a wiring diagram of 4the vehicle-detecting and waveshaping lcircuits of the invention;

Fig. 3 is a wiring Adiagram of the vehicle density averaging and indicating circuits;

Fig. 4 is a wiring diagram of the cycle computer;

Fig. 5v is ablock diagram indicating the mannerin kwhich Figs. 2, 3 and 4 are combined to form a complete circuit diagram of the preferred form of the invention;

Fig. `6 is a front elevation of a control panel from which the several circuits of the invention may be op erated.

Pig. 7 is "a graph illustrating the operation of the invention as applied to a traffic controlproblem.

Turning vto Fig. 1, the circuit Iof this invention yis there generally shown in block diagram. As shown, the'circuit here ina'y be actuated by four detectors identified as deI tectors 1 through 4. These detectors are of any 'standard type Vsuch as pressure action actuated and are not per ise part of this invention. The respective detectors are connected to individual pulse-forming circuits identified by the numerals 1, 2,13 and l4. These circuits serve topro- ,vide a pulse 'output as a result of the signal sent to them Aby their respective detectors. Each pulse former has its respective isolation diode as represented by box 5 in Fig. '1, and pulse forme'rs 1, 2, 3 'and 4 are connected to their respective isolation diodes by leads 6, 7, 8 Iand 9 respectively. YThe isolation diodes have the purpose of segrelgating each ofthe pulse-forming circuits from the remainder of the circuits of this invention. They also have included in their circuit neon indicating means, to be described below, which will indicate to the operator which 'ofthe various detectors is being operated. These neon indicating lights are represented by numerals 11, 12, 13 and 14.

It will be understood that this invention may be adapted for use with more or less than four detectors, if desirable, merely by adapting the principles herein set forth.

The pulse shaped output wave from the various isola- ,tion diodes 5 is connected by lead v18 to pulse Shaper 19. There the signal is amplified and sharpened so that the output signal is clean. This output signal is connected through lead 20 to flip-flop circuit 21 of substantially conventional well known design. The output of this circuit is a square wave having van output of one cycle for every two input: pulses, thus furnishing one cycle of output for each 'vehicle Which passes over a given detectorfsince two lpulses ywill be created by eachtwo-axle vehicle) For pur- *poses to be later described,'the flip-flop circuit is adapted to provide a full cycle of output'for every input vpulse whenbutaesingle'detectorfis in use. This moditication of operation is effected through a resistance connection in lane switch 22 connected to ip-op circuit 21 through lead 23.

The output of flip-flop circuit 21 is fed into pulse-Shaper 25 through lead 26. In this circuit, the square wave is differentiated to provide a positive pulse; and the positive pulse amplied, producing an output wave 180 out of phase so that the output of the pulse shaper 25 is a negative pulse. It will be noted that this output represents one negative pulse for every full cycle of operation of the flipflop circuit 21.

Connected to the pulse shaper 2S to receive the negative pulse output is a one-shot timed multi-vibrator 27 connected to the pulse shaper 25 through lead 28. This multi-vibrator is adapted to generate a full cycle square wave of predetermined amplitude and adjustable duration for each negative impulse received. The duration of the square wave output is subject to two controls by the operator of the device. The first is the 100% density control 29 connected to multi-vibrator 27 through lead 30. This density control in effect varies the timing of the multivibrator by means of a potentiometer varying the applied voltage, to be later described. Its purpose is to enable the loperator to set the circuit for the 100% density by assigning the approximate maximum level of traflic of the particular highway in question to the 100% point on the computer in accordance with ratings previously determined by traic engineers. As will be later described, this is an important setting since the circuit is adapted for alternative distribution of the traic control circuits being regulated in accordance with percentages of normal traffic density.

The other setting for the multi-vibrator 27 is through lane switch 22, connected to the multi-vibrator by lead 31. This lane switch has incorporated within itself capacitors of values bearing relationships inversely proportional to the numbers of detectors in the circuit at a given time, thus in effect serving to halve the time of the multivibrator cycle when the number of lanes is double and so maintain proportionate trac density percentages in the output circuits and associated meters or recorders. This lane switch, however, does not differentiate between the use of one and -two detectors in the preferred form due to the compensation previously mentioned which is applied bythe lane switch circuit 22 to the flip-flop circuit 21.

As will be seen, the output of multi-vibrator 27 then is a square wave of uniform and constant amplitude and of predetermined and calibrated duration. One cycle of output is had for each vinput impulse received from any one of the detectors in the circuit -at a given time.

The square wave output from multi-vibrator 27 is connected through lead 33 to charging circuit switch 34. This switch, in eifect, emphasizes and shapes the output wave so that the output from switch 34 is a square wave of precise amplitude and duration as timed by the multivibrator circuit. This output wave is impressed upon charge circuit 35 through lead 36. Charge circuit 35 controls the unit charge applied to a cumulative charge condenser for each pulse from switch 34 so that the total charge on this condenser will be linear with respect to the total number of pulses, for a given adjustment of output pulse length of the multi-vibrator circuit. L

The charge circuit 35 is coupled through lead37 to instantaneous density circuit 38. This latter circuit serves to sum up the charges impressed upon the charging circuit over a specific period of time in accordance with the RC constant of the circuit, this time period preferably being 20 seconds. Accordingly, output voltage can be obtained from the instantaneous density circuit 38 which substantially represents the density of the traiiic being measured at agiven time. This measurement can be shown on a meter connected in the instantaneous indicating and meas uring circuit 39, coupled to the output of instantaneous density circuit 38 through lead 40. The instantaneous indicating and measuring circuit 39 is alsoY coupled through lead 42 to the up-down averaging time circuit 43. This circuit has a second RC constant of longer and variable duration vordinarily having periods from one to nine minutes.

The output of the averaging time circuit 43 is fed into the averaging indicating measuring circuit 44 through line 45, for amplification and coupling to both the metering and control portions of the circuit.

The outputs of the instantaneous measuring circuit 39 and of the average measuring circuit 44 pass through leads 46 and 47 respectively, to switch 48 from which either one or the other may be connected to a density meter 50 or a recorder 51. The meter 50 is used to show the operator of the unit the density of the traic in the particular lanes being checked; and the recorder, for making a permanent record of same for later analysis.

Lead 52 takes another portion of the output of the average indicating measuring circuit and connects it to a distribution network composed of a vseries of relay networks 53, 54, 55, 56 and 57. These units togetherl constitute a cycle selecting computer and actuate relays,

so that any of the relays associated with circuits 53, 54,

55, 56 and S7 may be actuated according to the voltage on lead 52. As will be described below, only one of the output circuits from these relay units will be connected a-t a given time. Associated with each one of the units is an indicating neon light 58, 59, v 60, 61, 62 and 63, respectively, which serve to show the operator which one of the networks is in use ata given time.

The schematic circuit for the cycle computerof this invention is shown in Figs. 2, 3 and 4, which figures are interconnected as indicated in Fig. 5.

Turning to these figures, the four individual detectors are coupled to this cycle computer circuit in the lefthand portion of the drawing. The incoming series of leads from the detectors are indicated by numerals 70, 71,` 72 and 73. Since the four detectors are identical, only the one reached by the incoming leads 70 will be described. This will also apply to the subsequent pulse former circuits and isolation diode circuits. A switch 75 in line 70 may serve to connect the detector to the remainder of the circuit. One side of leads 70 pass through condenser 76 and the primary of transformer 77 back to the other of leads 70. Connected across the primary of transformer 77 is another condenser 78. A charge of 15 volts positive is placed upon condenser 76 from lead 79r which is connected to the voltage divider circuit made ,upI

most detectors, the type of detector to be used with thisl circuit is one having a normally open circuit temporarily closed as a result of the passage of a vehicle. This closing of the circuit, in effect, connects leads 70 together, thu's allowing condenser 76 to discharge and passing a pulse of current through the primary of transformer 77. A resulting pulse will appear on the secondary of transformer 77 and pass through series resistors 85 and 86 to the grid of triode 87. Triode 87 and its associated circuit represents the pulse former circuit previously described. There is acomparable pulse former circuit for each de tector and preferably its pulse former circuits will be made up by use of a double triode of the 5965 type.

If'desired, the detectors may be connected to the remainder of the circuit over standard telephone lines.

It is to be noted at this point that a power supply is available for furnishing the necessary direct current voltages needed in the various portions of the circuit. Since this is the conventional design, itwill not be described. Note, however, that line 88 carries 150 volts positive direct current from this power supply.

The series resistors 89 and 85 connected to voltage su'p ply 88 on one end and through the secondaries of :transformer -77 to ground on the other provideavoltage divid-1 ing .circuit which gives a positive bias'to-the grid of tube 81. The plate voltage of .tube k87 is'obtained through resistor 91 and the cathode ,of that tube is grounded.'

Tube 87 thus takes the pulse from the secondary of transformer 77 and shapes it for actuation of the cycle computer circuit. This pulse having resulted from vthe discharge of condenser 76 is substantially of a square wave form and has been further shaped by the limiting action of the circuit associated with tube 87.

The output of this tube is coupled to the entire cycle computer circuit through isolating diode circuit associated with diode 92 and represented in Fig. 1 by isolation diode circuit 5. This couplingis from the plate of tube 87 through lead 93 and capacitor 94 to the plate of diode 92. The plate of this tube is returned to vground through resistor 95, thus, in conjunction with capacitor 94, differentiating the input to this tube. The cathode of diode 92 is connected through lead 96 to lead 97 which in turn is connected ,through lead y98 and resistor 99 to. ground. An indicator light, preferably a neon tube 100 with incorporated series resistor -101, is connected bey tween lead 93 and lead V102 andthe latter passes through resistor 103 to ground.

Thus it can be seen` that the positive phase .of the wave output of triode 8 7 will pass through the circuit of diode92 through leads 96 and 9S to the grid of tube 110,` and the diode 92 effectively isolates the pulse forming tube 87 and its preceding circuit from the circuit following diode 92. Whenever there is an output wave fromapulse forming tube 87, Ait will also serve to light neon: indicator light 100 and so inform the operator that that circuit is operated.

It will be noted that the outputs of all fourof the isolation diodes, as represented by tube 92, are connected to lead 97 and thus through lead 98 to the `grid of triode 110. Likewise, all of the indicating neon lights, such as light 100, `are at the potential of lead 102 `to provide proper operating point for these lights.

Triode 110 and its associated circuits make up the pulse Shaper circuit 19 previously referred to. This circuit receives positive pulses from the output of the various isolation diodes and has as itsA output a sharp nega.- tive pulse which has been further shaped. The plate of triode 110 is connected to. D.C. voltage line 88 through resistor 111. The cathode. is biased positively by the voltage divider circuit consisting of resistors 112' and V103 connected between positive line 88 and ground. The cathode is also connected to ground through condenser 113.

The output of the pulse shaper circuit of tube 110 is led from the plate of that tube through lead 1,17, condenser 118 and lead 119 to both of the cathodes of the double triode 120, 121. Double triode 120, 121 is preferably of the 5965 type and this tube and its associated circuits make-up the, ip-op circuit represented by numeral 21 in Fig. 1. A

The ip-tlop circuitvof triodes 120 vand 121 is of a substantially conventional nature. The plate of tube -120 is connected to the source of positivo D.C. potential throughresistor 122 Vand `lead 123. The output of that plate passes through leadV 124 and the parallel combina-V tion of resistor 125 andv condenser 126 tothe grid of triode 121. The plate of triode 121 obtains its positive D.C. .potentialthrough resistor 12S. The output of the plate of triode 121 passes through lead 129 to the parallel combination of resistance 130 and condenser 131 to the grid of triode 1,20. The cathodes of the/two tubes are interconnected through lead 133 which is grounded through resistor 134,. The grid` of triode 121 is grounded through resistor 135. Thegrid of triode 120 passes through lead 137, resistor 138 and lead 139 to junction 140 associated with 'terminals of switch 141. YSwitch 141; as willbe described below, is lane switch 22 o fV Fig. 1. Junction 1401's directly connected to the positions of lane. switch-141% representing .2. 3 and. 4 lanes. H1t

`ground through lead 164 and resistance 165.

connected through resistor 142 to the lterminal' represent ing one lane. If, however, it is in the position representing one lane, there will be the series resistor 142"in:,the circuit, contact arm 180 Aconnecting via lead 188 to ground.

The parameters of the ip-llop circuit are so adjusted that for every pulse applied to its input, lead 119, there will be one-half cycle of operation, that is, one-half of the double triode will switch from conducting to nonconducting and the other half from non-conducting to conducting, as long as resistor 142 is not in the circuit. Under these circumstances, therefore, for every two input pulsesapplied to the cathode lead 133, one full cycle of operation will result. However, when switch 141 is in the one lane position and resistor 142 is .in :the circuit, the ip-op circuit will then act as a one-shot, multi-vibrator circuit and a full cycle willl be etected -by each input pulse.

As can be seen then when the circuit is adjusted for the 2, 3 or 4 lane positions, the two'pulses resulting from one automobile crossing a particular detector will result in but .one Cycle. With a single detector in use, that is with switch 14,1 in the one lane position, two full cycles will result. This, however, is compensated in the subsequent Aone-shot, multi-vibrator circuit 27, previously mentioned.

As with any circuit of the nature of the hip-flop circuit formed by tubes and 121, the output is in the form of a square wave. This output is preferably taken from the plate of triode 120, through leads 124 Aand 144,

condenser 145, lead 147 to the grid of triode 148. Lead.

147 is grounded through resistance 149 thus serving to differentiate the square wave output of the flip-hop circuit producing a differentiated wave consisting of a series of positive pulses, one for each output cycle of the flip-flop circuit.

Triode 148 and its associated circuits constitute `the pulse shaper 25 referred to in Fig. 1. The plate voltage is obtained from line 88 through resistor 152. rIhe grid of triode 148 is negatively biased by applying a positive potential to the cathode of this tube through the voltage divider circuit made up of a series of resistances 153 and 155 which are connected between line 88 and ground, the cathode being connected to the midpoint on these resistors. The cathode is connected to ground also through condenser 156. Thus, this pulse shaper tube 14S serves to amplify and shape the positive input pulse applied to its grid and produce a negative output pulse of predetermined form and amplitude on lead 15.8 running from the plate of that tube.

This negative pulse is led through lead 158, condenser 159 and lead 16) to the plate of triode 161. Triode 161 and triode 162 are preferably a double triode tube of the 5965 type and, together with their associated circuits, make up the one shot timed multi-vibrator circuit 27 referred to in Fig. 1. This multi-vibrator circuit is substantially of the normal type, except that it provides careu'llycalibrated'means for varying the RC constant by the capacitance and timing adjustment by voltage and thus for varying the period of the square wave out:- put. The plate of triode 161 is connected -to the source of D.C. positive potential 88 through lead 169 and rcsistance 163. The cathode of this tube is connected to The plate of tube 162 is connected to the D.C. potential 88 through lead 168, and resistance 169. The cathode of this tube is grounded through lead and resistance 165. The plate of triode 162 is connected with the grid of triode 161 through leads 168, 172 and the parallel combination made up of resistor 173 and condenser 174. The grid of triode 161 is also connected through resistor 175 tol ground.

It is ,in the grid circuit of triode 162 that the aforementioned calibrations of the output wave as to period arey obtained; This grid is connected through leads 17.6, and'.

177 to the other half of switch 141. This switch is a gang switch having two four position contacts. One side of the gang has previously` been described in connection with the ip-flop circuit and' junction point. 140. The other half of this gang switch serves to provide the capacitance in the connection between the grid of tube 162 and the plate of tube 161. Thus, lead 177 connects to the contact arrn of the second half of the gang switch 141 and may thus be connected to any one of four positions which represent the number of lanes or detectors in use. The terminals for the one and two lane positions are interconnected as one circuit, bridged by lead 178, and led through condenser 179 to lead 1.82. The contact position for the three-lane connection leads through condenser 183 to line 182 and for the four-lane position through condenser 184 to line 182. Lead 182 goes through lead 160 to the plate of triode 161. Thus, the capacitance for the RC constant of this half of the multi-vibrator circuit may be varied.

Capacitance 179 is preferably 0.01 microfarad. Capacitance 183 is preferably 0.0068 microfarad and capacitance 184 preferably 0.0051 microfarad. The ratio between these three capacitances, as can be seen, is substantially that of the reciprocals of 2, 3 and 4 respectively. Thus, the time constant can be varied in proportion to the number of detection units in use. This variation is proportionate to the number of detection units and so can serve to adjust the percentage density determination in accordance with the number of lanes used.

As previously described, when there is but one lane used the first half of gang switch 141 adds resistor 142 to the tiip-op circuit, making it a one shot multi-vibrator and so doubling the number of output pulses from the dip-flop circuit per input pulse in comparison to the number had when the resistor 142 is out of the circuit as when gang switch 141 is in either the 2, 3 or 4 line position. This variation compensates for the lack of aV separate larger condenser in the circuit leading betweenv the grid of tube 162 and the plate of tube 161 when the switch is set in the one-lane position. Accordingly, when the unit is set for one-lane operation, the time period of the output wave of the multi-vibrator circuit of tubes 161 i the grid of tube 162 is provided by the connection of grid lead 176 through lead 185 and resistor 186 to the variable tap of potentiometer 187. This potentiometer impresses a positive D.C. voltage upon the gridof tube 162 through the voltage divider circuit connected between the D.C. line 88 and ground. This circuit is made up of resistor 190 in series with variable resistor 191, parallel resistors 192 and 193, variable resistor 194 and resistor 195. Resistor 192 is the resistance of potentiometer 187. Variable resistors 191 and 194 are calibrating resistors used solely for adjustment of the circuit.

Potentiometer 187 is the traflic density control for the 100% indication on the density meter to be described below. Adjusting the potentiometer 187 toward the end of higher potential causesthe time to become shorter'as would correspond to a high density setting and, conversely, adjusting the potentiometer 187 toward the lower potential and provides a longer time period before tube 162 returns to its normal conducting condition, corresponding to a low density setting.

As will be described below in more detail, the object of theadjustments obtainable in the length'of the period of the youtput of this multi-vibrator circuit through potentiometer 187, in conjunction with resistor 186 and the condenser half of switch 141 are to vary the period in accordance with the number of detectors and the predetermined traiic density percentages of the highway in question. Accordingly, since the period of theoutput wave from the multi-vibrator determines the readings and of tubes 161 and 162 is preferably taken from the plate ofl tube 161 through leads 160, 182, 196, condenser 197, and lead 198 to the grid of triode 200. Triode 200 and its associated circuit is the charging circuit-switch 34 re-' ferred to in Fig. 1. The plate potential for this tube isv obtained from D C. line 88 through lead 201 and resistor 202. The grid of tube 200 is held at a positive potential of Volts but it is connected to lead 88 through lead 201 and resistance 203. The cathode of this tube is grounded.

As will appear below, the timing in this electronic cycle computer is determined by passing known amounts of charge through a resistor yfor each actuation impulse received from the multivibrator. In order to secure uniform charge from each actuation, the timed output of the one shot multivibrator, as received through leads 160,

182 and 196, is passed via condensed 197 to the grid of' switch tube 200. This tube is normally conducting due to the positive grid bias. Upon receipt of a timed negative', impulse from the one shot multivibrator, tube 200 be comes non-conducting and, therefore, its plate voltage` rises-to the applied D C. potential of 150 volts. This: positive change in voltage is directly connected via lead 204 through 4 microfarad condenser 205 and lead 206i to resistor 207. Essentially no drop occurs across condenser 20S during the timed interval so that, in effect, the full change in voltage which occurs in the plate circuit of switch 200 is applied to resistor 207.

Resistor 207 is connected to the plate of the diode tube 210. The cathode of this tube is connected through lead 211 to the parallel combination of resistor 212 and 2A microfarad condenser 213 and thence to ground. Thus the change in voltage applied to resistor 207 charges condenser 213 through diode 210. Resistor 207 controls the current, and the length of time that the one shot multivibrator is turned onv(ca1ibrated as above described) determines the amount of charge applied to resistor 212 and condenser 213.

Also connected to lead 206 through lead 215 is the cathode or diode 216. The plate of this diode is connected through lead 217 and resistance 218 to a source of 150 volts negative D.C. potential is obtained from the power supply.

This plate is alsorconnected through lead 220 and re-y sistance 221 to lead 215. The charge side of condenser 213 is applied through lead 225 to the grid of triode 226. This tube and-its associated circuits are referred to in Fig. V1 as the instantaneous density measuring circuit 39. The cathode of tube 226 leads through resistance 227, lead 228 and resistance 229 to ground. The cathode is also connected through resistor 230 to lead 217. This triode 226 is connected as a cathode follower for purposes to be later described. The plate of tube 226 is connected through lead 233 to the cathode of triode 234, the plate of which is connected to a source of 300 volts positive potential identified by line 235. The grid of this latter tube is also connected to this potentinal through resistance 236. This grid is connected to the plate of gas filled tube 240, the cathode of which is connected through line 241 to the cathode of triode 226.

Thus it can be seen that the voltage on condenser 213 is applied directly to the grid of tube 226. Since this latter tube is a cathode follower circuit arrangement, the cathode essentially follows the grid voltage and through a potential divider combination comprising resistors 230 and 218, the voltage from the junction of these two resistors passes through diode 216 and is used as the restoration voltage for the one side of condenser 205 when the switchtube 200 is turned off. Therefore, the combination operates such that if a timed detector impulse is received, an added potential difference appears at resistor 212 and condenser 213. Since the side of con' denser' 2.95. f totana-rse 2.0.7 isI retntned entita-.end Of: each. @sie to essentiallr the Same voltage that then exists on condenser 21,3@ asya. result ofthe voltage divider` cireuit; associated;- with. diode 2 16,l the arrangement provides thel charging. reSSIQl'. 2.07- withthe Seme voltage. for. @acht impulse.: regardless; Qt. the voltage existing on condenser 21,3, This allowsf for#y alinear in-A crease of the voltage on condenser: 213 Correspondingto the-numberofg impulses.

Thus, it cangbe seen lthatfthe voltage onv condenser-v 213 is, a function ofl the number of; impulses. received by: it perjunit timetogethen withl the RQ constant which determines its discharge time-` Resistor 2 12 is preferably L0 megphms. and; Condenser; 2.13,. 2.'. mictofarads.. proerably 10 mecohmsandcndnser 1'3. microtarads, pro.- vidinga timeI constant ofn 2Q seco t This- 20 second; period. is, herein referred to. as the-instantaneous;reading,v since the voltage on. condenser; 2,13;- proportionate to thenumber. Qffimrulsssper. unittimeove-rtthe 2.0 seconds; inst'prec,eding- The Alta-srV Corresponding; to.; instant densitymay: beV measured;` atthe; catl'iorlgz;l of-, tube' 2,263.' In order to, intr. more thelimit of; Iiueanityt Ofzthc operation ofi this: ein. .uit, g as tubo 2.40ashasrereyiouslyf beendescribed, is

connected. to the cathode. circuit. o f tube11226. with. its..

voltage for, tube` 22,6;as gridgvoltg is .applied toit. If.` the tubesfZfw and:234awerefnctiprnvideditheilargevoltagef. increaseat thetcathodeot: tnbc 22.6 wonld-consumeimosr' 0i they cathode. to n1atetvoltagef-onr-.thisr tube-and, there. fQte,.there-.Would;be iConsiderable.droppingtofor decay;

' Ofcthe linearity Qt: ontput; october- 221iI for latgetiuput voltages...

. The average;densityW measuring andi-indicatingv circuiti 44 and the up-down averaging time circuit '431er Fig; 1v willI nowbe described.` The cathode voltagefottubez`226 taken from.- line; 241` is; aA` DE.. voltage. corresponding. to. the instantaneous trafiicydensity: This; voltage. islnow which is variable from one tonine minutesxin order to obtain, an; average density. measurement xover the selected longen time period, Accordingly, the voltage on line`241 is., led through li n e 2 42. to. thelowerendof the? group ofl seriesliresistorsgZf, 244, 2.45,. 246', 2471 andz248. The junptiond points; 0fthese. resistorsare: each= connected to a terminal of. the..r multifposition; switch- `250, they output fromihs; switch being obtained.on.lne 255; Line-'255 leads intol a; second multi-position;v switch. 2561 having termina-1s; associatedwith-.a-.second groupof comparableseries, resistorsy 257258 252.260, 261 and 262. Thesey resistors v are connected. .throughlines 265,. resistance. 266 andline 267 to seriescondensers 268:?and265l` respectively;

Condenser 269 has,.a dual function.v PlsidcterminedA voltage with.. respectn to:` ground sov that whenv the apparatus;.is: firstturned i on-,, the apparatus operates.; as if this; voltage were` storedl in` condenserV 268V and thus the apparatus will'startauptat atpredetermined" desired.startingtlevelzofthe or'dersof 70% -onithe O 100% A densityscale,4 for example.v Another function ofiicion-I denser;` 2.6.9. is.` to. perrniticondenserr 26810 V,betoperated' at approximately one; half of;thecvoltagefittwould have to .t have ifits; return. were .connected1zdirectly, to` ground. 1

Thus it Gambe.: seentthatzthe .no ternal..receivedA from dit.y instantaneousdensita.measuringgctenitaon 1e.ad.s.;2 41. andlsgses. tltrnrshtcnesot.tbecrnastcrsfassnetatedrwnn It: providesvv a thegctcut". offswitch 250 and thence through one of that; resistors associated with circuit 256 through lead; 265@ resistance` 26,6lead 267 and condenser-s 268 and. 269.:A A-,chargeis thus added to condenser 268 in this manner.- 'Ihe RCatime constant may be different for a situatiotr where; there is rising voltage as against where the'voltaget is: falling. When the voltage on line 241 is increasing,. current will ow from line 241 through line 275, lint:l 276 and the left side of double diode 277 throughlinez27f to switch 256. and its associated resistance. When it; is; decreasing, the flow will be from line 241 through line:

l 242 one of the resistances associated with switch 250;.:

line, 25,5line 278the righthand side of diode 277 and". leadi280, toresistor 266 and beyond. Consequently: the

: tirne,.constant of' this circuitmay be diierent. in periods;

ofY rising voltage from that of decreasing voltage depend-.f ingupon-thesettings ofY switches 25.0 and. 256.

Voltage/on line.241y is determined by the 20 second or` instantaneous, traic density, whereas thevoltageon; line: 267JS determined bythe. longerl period or average-rtraic density; the integrating period of which is setfbyf'thet switches; 25,0zand; 2.56.. Thus, when the instantaneous? traffic density isgfhigher than the average traffic density; the'intcgrating rate set by switch 256.wil1 be in effect; and. in. thel reverse case the integrating period. set4 by( switch 2,51iis; in effect, which will correspond generallyg. but not necessarily always, with increasing and decrees` inggtraicdensity respectively.

A condenser 279 is connected across lines 276 and 278*` t toeliminate any 60 cycle hum which may 'existin the circuit.y Y

The object of having two separate banks of resistances;. oneassociated with each of switches 250 and 2562istrxz provide f or two different time constants for the up-down. averagingv time circuit 43. As stated, which bank is used. depends. upon whether the voltage represented by ther average density is increasing or decreasing, that is, wheth.

er; the.. instantaneous density is higher or lower thanthc:`

average density; This is desirable since traffic situationsmay-arise in which more rapid change from one cycle:A

A circuitltol another cycle circuit is desirable either when.

the trahiev is increasingV or when it is decreasing. Inshort, greater flexibility is provided.

LAspreviously mentioned, the positive voltage on con'h denser 268k at .line 267 is a function of the trafc density average over the particular time period selected by switches 250 and 256. This is referred to as the average density. This voltage is applied to the grid of triode 28S, which is wired as a cathode follower. This tube and its associated circuits is referred to in Fig. l as the average' indicating measuring circuit 44. The plate of'this'triod'e' 285 is connected through lead 284 to the cathode of`tn`- ode'286, the plate of that tube being connected to lead' 235,v the source of 300 volts positive D.C. potential.' Thegrid of tube 286 is also connected through resistor 287to line235. This grid is connected in addition to 'they plate of gas tube 290,*p1eferably the OBZ type; the cathode is connected through leads 291 and 292 to the cathode of triode 285. Cathode of rtriode 285 .is connected.l

through series Aresistors 293. and 294 to ground, thus,

completing the cathode follower circuit. y

The operation of tubes 286 and 290 in association withtube 285,is. to improve the limit of linearity of thef opera-l tioniofl thiscircuit and corresponds in operation to tubes 234 and 240 associated with triode 226.

It can be seen, therefore, that the voltage obtained on junction point 297 between resistors 293 and 294y fol, lows the voltage applied to the grid of tubeA 285 and so is .directly proportional to the voltage on condenser 268 which represents the averagetraic density. Correspondf= ingly, the voltage at junction point 298, located between; resistors 227 and229, is proportional to the instantaneous: traffic, density, as: has. been=above described..

Thesefvoltages. amused. to. operate` a.. meter .on a rca aasaoos corder and the cycle'controlling circuits for the distribution network. e

' Two-gang multiple position switch 300 serves to complete the circuits for utilization of either of the two voltages. The first gang of the switch, as represented by the upper half above the insulator 299 in Fig. 3, serves to connect either of these voltages or testing voltages with the milliameter 301 through line 302. vIn the lirst position of the switch, the instant density voltage from junction point 298 is connected to the meter through lead 303, variable Calibrating resistance 304, and lead 305. The second gang of the switch 300, when it is in the iirst position, serves to complete the meter circuit. The other side of the meter is connected through lead 307, resistor 308, lead 309 (which bridges connecting terminals 310 and 311 when a recorder is not in use), lead 312, the second gang of switch 300, lead 313, and potentiometer circuit 314 connected at the variable tap 315. This po tentiometer circuit consists of series resistors 316, 317, and 318 connected between a source of 150 volts positive potential and ground. The variable tap 315 is on potentiometer 319 which is wired in parallel with resistor 317.

When switch 300 is in its second position, the meter and recorder will be actuated not by the instantaneous density voltage but by the average density voltage. This is obtained from junction point 297 through lead 322, variable calibrating resistance 323, and lead 324, connecting with the second terminal of the first gang of switch 300. The circuit to the meter is then completed, as with the iirst position ofthe switch, except that lead 312 now connects through they second gang of the switch, thence to lead 326 and the variable tap on resistor 317, previously described. f

The remaining positions of switch'300 are for purposes of testing the accuracy of the power` supply voltages. When the switch is in the third position, lead 302 going into the meter will then be connected to a source of 300 volts positive potential through resistor 328 and lead 329, going into the third position terminal of the iirst gang of the switch. Lead 312 will be connected through thesecond gang of the switch to ground by lead 334, thus resulting in an application of 300 volts potential to meter 301.

A second test point is the 150 volt positive potential test obtained in the fourth positionof gang switch 300 through resistor 332 and lead 333. In this instance, lead 312 from the meter is connected to ground throughthe fourth position of the second gang of switch 300 and lead 330. e v

The negative potential of 150 volts is tested when switch 300is in its fifth and last position. In that instance, lead 302 is grounded through the iirst gang of the switch and-lead 335. The negative potential is applied to the meter`through resistor 337, lead 338 and the iifth position `of the second gang of switch 300 connecting to lead 312.` `It will be understood that in'each instance of voltage tests, the meter will have been previously calibrated. Y As previously mentioned, a recorder vof any standard type may be placed in the circuit. v In this instance bridge 309 is broken between terminals 310 and 311, and the recorder is connected to these terminals. A bridge is then placed between terminal 310 and terminal 339, shorting out resistance 308 and thus maintaining the balance of the circuit.

,One of the primary `objects of the present invention is to provide a means for switching on one of a plurality of traliic control circuits as selected by the traffic density in the various highway lanes being detected. This is best accomplished by the network distribution circuit now to be described. Y f

Lead 292 connected to the cathode of tube 285 in a cathode follower type of circuit reflects, as had previously" been described, a voltage proportionate to the positive circuits for theremaining tubes are comparable.

voltage on lead 267. This voltage is a function of the' average traffic density over the time period set in aecordance with switches 250 and 256. Thus, the voltage on lead 292 is a positive direct current voltage following slowly over the averaging period in accordance with mally in the down position as shown in the drawings when their respective relay coils are de-energized. Thus, relay coil 352 actuates armatures 357 and 358; coil 353 ,actuates armatures 359 and 360; coil 354 actuates armatures 361 and 362; coil 355 actuates armatures 363 and 364; and coil 356 actuates armatures 365 and 366.

The grid of triode 346 is connected through lead 370 to armature 357 and from there through condenser 371 to ground. The cathode of 4that tube is grounded. The The grid on tube 347 is connected through lead 372 to armature 359 and then through condenser 373. The grid of tube 348 is connected to armature 361 by lead 374 and then through condenser 375 to ground. The grid on tube 349 is connected to armature 363 through lead 376 and then through condenser 377 to ground. The grid of vtube 350 is connected through lead 378 to armature 365 and then through condenser 379 to ground. The cathodes of each of these tubes are grounded.

Each of these five triodes has a grid signal applied to it which isa function of the voltage on line 345, the voltage set on a Calibrating voltage dividing network, and whether or not the tube is at a given time conducting or non-conducting. The voltage dividing net-work is `made up first of series resistors 385, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396 and 397 connected between a source of minus 150 volts D C. potential and ground, the first of these resistors being a grounded one. Resistors 385 and 397 are variable resistors so that the initial adjustments to the circuit to provide for zero percentage and traliic density may be made.

The Vvoltage ldividing net-work for'tube 346 is made vup of lead 400 connected between resistors 386 and 387 and going to parallel resistors 401 and 402 which are connected to lead 403 which runs to the junction point between resistances 391 and 392. Resistors 405 and 406 are series connected between input lead- 345 and a variable tap on yresistance 401. The lower contact point 407 for armature 357 is connected between resistances 405 and 406. Resistances 409 and 410 are connected in series between lead 345 and the variable tap on resistance 402. The mid-point of these two resistances is connected to the upper contact point 411 on armature 357.

The circuit arrangement for obtaining grid bias on the other four tubes is comparable, thus parallel resistances 415 and 416 are connected between the junction point of resistances 387 and 388 and the junctionpoint of resistances 392 and 393. Series resistors 417 and 418 lead from line 345 to the variable tap on resistance 415, their mid-point being connected to lower contact point 419 and armature 359. Resistances 420 and 421 are connected in series between line 345 and the variable tap on resistance 416, their mid-point being connected to the upper contact point 422 of armature 359.

Parallel resistances 425 and 426 are connectedv between the mid-point of resistances 388 and 389 and the midpoint of resistances 393 and 394. Resistances 427 and 428 are connected in series between line 345 and the variable tap on resistance 425, their mid-point being Aconnected to the lower contact point 429 of armature the lower contact point 449 of armature 365.

361. Series resistances :430 .and 431 are connected in `series between line 345 and the variable tap on resistance 4.26. Vtheir midpoint .beine Connected Vt0 the upper Qontact point 432 of armature 36,1. Parallel resistances 435; `and 436 are connected between the junction .of resistances 389 and 390 and the junction to resistances 39.4 and 395. Series resistors 437 and 438 are connected between lline 3.45 and the variable tap on resistance 435, their midpoint being connected to the lower contact point 439 .of :armature 363. Series resistors 440 and 441 are connected between line 345 and the variable tap on resistance 436, their mid-point being connected to the Icontact point .4.42 of armature 363.

Parallel resistances 445 and .446 are ,connected between the junction of resistances 390 and 391 vand the junction of yresistances 395 and 396. Series resistances 447 and 448 are connected between line 345 and the variable tap and resistance 445, their mid-point being connected to V,Series ...resistances 450 and 451er@ @arrested between line 34.5 and the variable tap on resistor 446, r4and Vtheir mid-point is Connected t0 the upper vente@ .arm 4529f1rmature 36,5-

Associated with ,each .one .o f .the tive triodes and their respective relays are ve distribution circuits .which are designed to provide a voltage on .any one at any given time to actuate the outside circuits. The objective is to `have but one outside circuit, such as .a tratiic control circuit, operated at any given time and to switch lfrom any one to any other of the actuating circuits in .accordance `.with the control voltage found on line 345 and representting the average traiilc density.

A voltage to be applied to the trahie .control .ein Auit is represented at 460 as positive voltage. As shown in the drawing, this voltage goes through lead 461 through `arrna- Ature 366, lower contact point 462, lead 463, armature 4364, 4lower contact point 465, lead 466, armature 362, ylower .contact point `467, lead 468, armature A360, lower .contact point V469, lead .470, armature V358, vlower .contact point 471 and lead 472 to output control point A. `It will be understood that this circuit will be lbroken Vif any o f the ve armatures are raised `as would occur when `the respective armature coil is energized. This latter occurs vwhen the particular tube in series with the coil :becomes conducting, as will be described below. Associated .with armatures 358, 360, 362, 364 and 366 are upper contact lpoints 475, 476, 477, 478, 479, respectively, which conl-nect the armature to output control points B, C ,D, E :and F, respectively. The six control points A through F are comparable to the similar control points shown in the above mentioned Patent Number 2,288,601. It Vis therefore seen that there have been provided six different control possibilities in this circuit, though the circuit may easily be designed for a greater or fewer number, if such is desirable.

So that the operator of the unit may know which par- ;ticular output control circuit is in operation at a given time, there are provided neon indicating lamps 480, 481, .48.2, 483, 434 and 485 connected between the respective lcontact points A through F ,inclusive and ground. As indicated in the circuit, each of these neon lights whas incorporated withinits owncircuit a series resistor; as va. satisfactory tube for this purpose would .he one of the NESl type.

As previously mentioned, this distribution netework control circuit is controlled by the positive voltage on line 345. In the drawing as shown, all of the .coils 352 through 356 are de-energized and their respective armatures are in their normal or resiliently biased position so that the control voltage from point 4,60 is fed to con- Atrol point A. This would indicate that the voltage on line 345 is very low due to low traicdensity, for example.

The points in terms .of percentage traliic density lat which it is desired that the distribution net-work Ibe Wi-.lished from one contrat-reim 10 @ether when the 1,6 voltage `ori- line 3,45 isincreasing Aare se t by adjusting the variable taps on resistances 401', 415, 425, 435 and respectively. Since each of these variable taps is associated with a voltage divider circnit, the voltage obtained on each of these taps can be varied. These voltages, however, should be so adjusted as to become more negative as we move from the tap on resistance 401 to the tap on resistance 445. This adjustment then, as will be later described, sets the point at which the respective tubes become conducting and so energize their respective relay circuits.

Comparably, the taps on resistances 402, 416, ,426, 436 and 446 are adjusted for use when the voltage on line 345 is decreasing. These voltages also are more nega; 'tive with respect `to each other as we go from that on the ,tap associated with resistance 402 to that on the y'tap associated with resistance 446. It is to be noted, however, that the voltage ,on the tap associated with resistance' 401 is less negative than the voltage on the tap associated with resistance 402. This also applies to resistances 415 and 416, resistances 425 and 4 26, resistances 435 and 436 and resistances 445 and 446. This difference in yoltage allows the trafic density percentage, at which point the circuit switches from one output control to another, ,to be greaterfor increasing as against decreasing traflc volume.

As stated above, the relays as shown in this drawing are all in their de-energized positions. In this situation, the grid voltage on triode 346 is obtained through lead 370, armature 357, and lower contact point 407; it will be seen that series lresistances 405 and 406 comprise a voltage dividing net-work as between line 345 and the tap on resistance 401, thus providing the grid voltage on lower contact point 407. When the voltage in line'345 Vbecomes sufciently high to bring the voltage .at point 407 above the cutoff voltage for tube 346, this tube will then conduct. Once it conducts, coil 352 will be energized and relay armatures 357 and 358 will beshifted to their energized positions, contacting the `upper c ontact points 411 and 475, respectively. The Ccontact arms 358, 360, 36,2, 364 and 366 Vare all adjusted to make before they b reak contact.

The contact arms 357 and 358 having connected to their respective energized contact points 411 and 475, it will be seen then that the voltage 460 will no longer be applied to control point A but will now be applied to control point B, and that the grid voltage for tube V346 will no longer be obtained from point 407 .but will be obtained from point 411 (point 411 being connected to the mid-point of resistors 409 and 410 which make upna voltage dividing network between line 345 and potentiometer 402), and the voltage on the grid of 4tube 346 will thereafter be controlled in accordance with the voltage set on the tap on resistance 402 for decreasing vtratiit: density. Since the voltage on the tap on resistance 402 is less negative than the voltage on the ytap on resistance 401, the grid voltage resulting iwill be vabove the cut-off point until the voltage on line 345 drops .below that which the line had when tube 346 rst became conducting.

It will be seen due to the different and more negative settings of the .potentiometer networksassociated 4with Vthe other four tubes that at the .point at which the voltage on line 345 'becomes Vsuliiciently positive to cause tube 346 to conduct, as previously described, it rwill not be suddciently positiveiito cause any yof the .remaining tubes to conduct. As it increases, however, the voltage on lower contact point 419 likewiseincreases in-accofrdanee with the setting of vthe variable tap associated with variable resistance 415. At a `certain point, vas the voltage in line 345 increases, the voltageoncontact point L419 ,willreach the cut-ott voltage of tube 347. l Since this voltage ,at point 419 is applied to the grid of tube 347 throughcontact arm 359 and .lead 372, this tube will then become conducting. When ythis occurs, .relay coil 353 .will ,be energizedgnd relay amis .359 and 360 move totheir 117 second position, justas happened with respect to the circuit of tube 346. Since contact arm 360 is no longer contacting lower point 469, voltage 460 will no longer be applied to control point B, but rather it will be applied through upper contact point 476 to control point C. This is so even though tube 346 is conducting at the same time as tube 347. v l

lf the voltage on line 345 continues to increase, tubes 34S, 349 and 350 will alsobecome conducting in thatY order and will thus actuate the relays in the same manner as in prior stages and shift the control points. 1t will be noted in this respect that the control point which is energized by the potential from point 460 will be the one associated with the most righthand of the live triodes as shown in the drawing.

Assuming that the voltage on line 345 is high enough for tubes 346 and 347 to be made conducting but not high enough for the remaining tubes: to be made conducting, then it will be control point C that will be energized in accordance with ythe previous description.

lf the voltage Yon lline 345 now decreases there will come a point at which the voltage on upper contact point 422, as obtained from the voltage dividing network made up of resistances 420 and 421, will drop below the cut-oit` voltage for triode 347. The term cut-off here means the point at which suicient plate current owsvto operate relay 353, this being preferably near the maximum slope on the 1/Eg characteristic curve, rather than at the actual point of cut off of plate current 'by grid bias'. At this instant relay 353 will become de-energized and relay arms 359 and 360 will drop to their de-energized normal positions. This will disconnect control point C and connect control point B (since tube 346 will at that point be conducting). It will also provide that the bias on the grid of tube 347 will now come from point 419 asr previ ously described.

As the voltage on lineV 345 continues to decrease, then grid voltage on point 411 which is being applied to tube 346 will finally go below cut-oi and that tube will also become nonfconducting, shifting the control point from B to A in a comparable manner.

Thus it can be seen that the tive triodes, 346, 347, 340, 349 and 350 and their associated relay networks provide a means by which the particular control point energized at a given time may be instantaneously changed to any other control point as determined solely by the average traflic density control voltage impressed on line 345. It will also be seen that, if desirable, the particular traffic control voltage at which the shift is made from one control point to another control point may be diierent, depending upon whether the voltage in line 345 is decreasing or increasing. s

In the practice of thisy invention, it is preferable to have the variable taps associated with resistances 401, 415, 425, 435 and 445 calibrated in terms ot the percentage traffic density at which itis desired to have the control points switched during periods of increasing trafc density. Comparably, it is desirable to have the taps on the resistances 402, 416, 426, 436 and 446 calibrated in terms of percentage traic density for periods in which traic is decreasing.

Turning to Figure 6, we have there illustrated a control board 489 of type which could be used within the described electronic cycle computer. In the operation of the unit, the calculated 100% tratiic density of the particular highway being detected is set with knob 490 which actuates potentiometer 187. The number of lines being detected, that is, the number of detectors being used, is set with knob 491 Ywhich operates lane switch 141. The desired averaging period for increased density is set with knob 492 which actuates multiple position switch 256. Likewise, the desired averaging period for decreasing density is set with knob 493 which is the same as multiple switch 250. The detectors that are in operation may be controlled by the onfoi switches identied as 494, 495,

respectively.

18 496, and' 497 which are the switches located on the incoming lines 70, 71, 72 and '73 from the detectors. Each detector switch has located above it on the panel an indicator light, such as neon light previously described.

The point at which the distribution network control circuit is to switch from one control point to another for increasing tratlic is set 'by knobs 500', 501, 502, 503 and 504. These knobs control the taps on resistances 401, 415, 425, 435 and 445 respectively. The point of switch during periods of -decreasing traiiic density is set by knobs 505, 506, 507, 50S and 509 which` control the taps on variable resistances 402, 416, 426, 436 and 446, these latter knobs being concentric with the knobs 500 to 504, It has been found that it is preferable to set the point for decreasing density switching approximateiy 5% below that for the increasing density switching. Thus, for example, knob 505 might be set for a 20% trafic density while knob 500 would be set for 25% traffic density.

These concentric knobs are interlocked by means of the peg 520 projecting below the inner knob and the pin 521 shown to the left of this peg and mountedon the outer knob, so that the inner knob cannot be set any higher than 5% below the outer knob on the scale.

Associated with each of the concentric pairs of traffic control density knobs (as knobs 500 and 505) is an indicator light to show which control circuit is in operation at a particular time. Thus, on the panel are lights-510, 511, 512, 513, 514, 515 which correspond to neon lights 430, 481, 482, 483, 484 and 485 respectively.

Also mounted in the panel board of Figure 6 is a percentage traflic density meter 516. This is the meter 301 shown on the circuit diagrams. Located below the percentage traffic meter 516 is a meter selector switch 517. This is switch 300 of the circuit and shows points for showing instant density, average density and checking the voltage as previously described. Preferably contact points 310 and 311 for the connectionof an outside graphic recorder, such as a recording milli-amrneter properly calibrated, will not be on the panel board but this, of course, is optional with the user.

The operation of the electronic cycle computer of this invention has been described above with reference to the particular stages of the circuit under consideration and its operation has been also explained in the description of the panel board shown in Fig. 6.

Once the detectors have been properly connected in accordance with the usual practice and the control points A through F have been also connected to the usual types of selective traffic actuating mechanisms, the operator then sets the controls on the panel board of Fig. 6 for the specific mode of operation desired. After checking the voltage by using the third, fourth and fifth positions of the meter selector 517 and noting the voltages on meter 516, the calculatedk trafc density for the highway under consideration is set on density control knob 490. In Fig. 6 this knob is shown as set for a highway havinga calculated 100% traffic density of 700 vehicles per hour per lane.

The vehicle detectors are turned on, as desired, with knobs 494, 495, 496 and 497 and the number of detected lanes set with knob 491. The operator then determines the desiredaveraging periods for increasing and decreasing densities, in accordance with the trac conditions eX- pected to be encountered, and these are then set with knobs 4972 and 493.

The switchover points to shift the operation from one cycle, that is one control point, to another are then set, both by means of dials 500 to 509, inclusive, as previously described. The setting of these dials will determine invterms of percentage of traffic density when the switch will be made during increasing and decreasing trac periods. An example of possible settings for the traflic density switch controls 500 to 509 is illustrated in Fig. 7. This chart shows the switchover points for the various cycles as the panel board has been set in Fig. 6. Thus, beginning with a zero percentage traffic density and increasing to 100% it will be seen that cycle A will be controlling until the traic reaches 25% density, at which point cycle B will control; when 40% is reached, it 4will switch to cycle C where it will remain until it reaches 55%, at which point a switch is made to cycle D. At the 70% point, a switch will be made to E and at the 85% point'to F. When the percentages are decreasing from 100%, it will be seen that the circuit will switch to cycle E at 80%, to cycle D at 65%, to cycle C at 50%, to cycle B at 35% and to cycle A at 20%. It should be noted that due to the design of the distribution network control circuit, these switches from one to another cycle will be made substantially instantly as the voltage in line 345 corresponding to changes in trafc density varies.

e As previously described, the actuation of any of the detectors by a passing vehicle serves to close the detector circuit twice (once for each axle) thus producing a pulse wave in the primary and secondary of transformer 77. This wave will be formed in tube 87 and the positive phase of this wave will pass through isolation diode 92 to leads 97 and 98 to pulse sharpening tube 110. At the same time, these input pulses can be observed visu- -ally on neon tube 100 on the panel board. The output of pulse sharpening tube 110 will be a sharp negative pulse which is carried by lead 117, condenser 118 and lead 119 to the ip-op circuit represented by triodes 120 and 121. Except when the circuit is set for single 'lane detection, each pulse will cause one-half cycle of operation of the ip-flop circuit, thus producing one full cycle for every vehicle detected. Where single lane operation is called for, two complete output cycles will result from each vehicle.

` The square wave output of the Hip-flop circuit is carried out by lead 124, the differentiating circuit made up of condenser 145, lead 146 and resistance 149, and lead 147 to the grid of a second pulse sharpening tube 148. Since the wave is differentiated it will take a pulse form and the output of the pulse sharpening tube 148 will be a series of negative pulses impressed upon lead 158.

This signal then passes into the biased multi-vibrator circuit represented by triodes 161 and 162. The period of this circuit has been previously adjusted by the psitioning of switch 141 and potentiometer 187 and, as a result, the output of the multi-vibrator circuit is a `wave of predetermined amplitude and carefully calibrated period. This output wave is fed into the grid of charging circuit switch tube 200 and serves to change it from normally conducting to temporarily non-conducting, in accordance with the predetermined period ot the multi- Ivibrator.

The output from the tube 200 passes through condenser 205, resistance 207, and diode 210 vto the parallel combination of resistance 212 and condenser 213. The magnitude of the charge applied to condenser 213 will be determined by the period of the multi-vibrator circuit and consequently the voltage across the condenser 213 at any particular time will be a function of the number of charges the condenser has received and the magnitude of those charges for a given value of resistor 212. Thus, this voltage represents the traffic density calibrated in terms of percentage on the basis of the calculated 100% traic density for the highway (switch 490).

vThe voltage on condenser 213 is led through lead 225 "to the instantaneous density measuring and indicating circuit as represented by tube 226 and its associated circuits. The output voltage of 226 is obtained on lead 241 and passes through the average density measuring and indicating circuit to condenser 268 in the marmer previously described. The voltage on condenser 268 vwill 20 represent the average traic density over the previously selected time period.

This voltage on condenser 268 is amplied in cathode follower circuit 285 and its associated circuit and passes-first through resistor 293, junction 297, lead 322 and the resistance 323 and lead 324 to switch 300 from where it may be used to actuate the meter or recorder. This voltage secondly passes into lead 292 and lead 345 and is utilized to operate the distribution net-work control circuit, as previously described.

Although the values employed for resistors and condensers used in the system as well as the several vacuum tubes that are employed may be varied within wide limits according to the network of a particular installation the several components described above have been found to produce good results in a practicable embodiment of the invention when thefollowing values were employed:

Tubes Ref. No. Tube type Ret. No Tube type 87 5965/,2 210 ALS 92 6AM/2 gig "5s14A/2 11%) $6122 zss 5s14A/2 Resistors Ref. No Ohms Ref. No. Ohms 81 2K 218 200K 82 17K 221 200K 83 300 227 23.5K 85 100K 229 680 86 100K 230 15K 89 3.9 meg. 236 360K 91 20K 243 1s meg. 95 200K 244 6 meg 99 100K 245 6 meg 103 20K 246 6 meg 111 51K 247 6 meg 112 200K 248 6 meg 122 15K 257 6 meg 125 390K 258 6 meg 128 15K 259 6 meg. 130 390K 260 6 meg. 134 6.8K 261 6 meg. 135 100K 262 18 meg. 138 100K 266 6 meg. 142 510K 271 100K 149 100K 272 100K 152 10K 287 360 153 20K 293 235K 155 200K 294 680 163 15K 304 2K 165 6.8K 308 2K 169 15K 316 75K 173 390K 317 400 175 100K 318 100 186 510K 319 400 190 34K 323 2K 191 10K 328 450K 192 100K 332 225K 193 50K 337 225K 194 10K 385 2K 195 13K 386 1.8K 202 13.5K 387 1.5K 203 1 meg. 388 1.8K 207 27K, 389 2.3K 212 10. meg. 390 2.8K

Although the foregoing description has defined the basic concept of the invention as applied to a vehicular traffic system, it is apparent that the invention is not limited to this purpose but is capable of much broader application. For example, the device may be used in connection with supplying air to a vehicular tunnel for the purpose of ventilation. Obviously, in such an application it is easier to keep the air supply within readily predetermined limits in order to provide sufficient ventilation for the number of cars using the tunnel and at the same time to avoid oversupplying the tunnel with a consequent Waste of power. In such an application, vehicle detecting devices as described above or of any other suitable type such as photo-electric, may be placed at the approaches to the tunnel and the Ventilating machinery may be controlled in very much the same manner as described above to insure adequate ventilation as a function of the number of cars using the tunnel. The invention is equally applicable in the field of auto mation wherein a plurality of conveyor lines, each carrying a separate component of a product, in essence converge at one assembly point. In such an application an over-supply or under-supply of any component of the product can cause costly and time consuming delays unless detected in adequate time. To those skilled in the control of such processes, the manner of application of the present invention will be readily apparent.

It will be appreciated that the term traffic density is used herein in the sense of traflic volume per lane or rate of trafiic liow in vehicles per unit time passing a givenV point or points, depending on whether one or .more detectors are used. Such trahie volume may be expressed in vehicles per hour, per lane for example on adjusting switch @fr The term density is also used in its more general sense as the incoming pulse rate per unitv time from the input or detector circuits.

It will be obvious to those skilled in the art that the Vv22 several triodes 346 through 350 might be replaced by gas discharge tubees of the type 885 or Thyratron type with an alternating current voltage source applied to line 351 instead of the direct current voltage source 145B shown, if desired.

From the foregoing description, it is apparent that the several objects of the invention are achieved. Obviously, many variations may be made without departing from the scope of invention and Would include modifications of both Wave shape and Wave polarity in various of the stages of the circuit.

I claim:

1. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second avv eraging circuit having a specified time constant greater than the time constant of'said first averaging circuit for receiving the voltage generated by said first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a selected time period, a plurality of utilization device actuating circuits, and a control circuit capable of selectively actuating`one of said utilization circuits in accordance with the magnitude of said control voltage.

2. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude and of adjustable period in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a specified time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a selected time period, a plurality of utilization device actuating circuits, and a control circuit capable of selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage.

3. A circuit of the character described, including a pulse generating circuit capable of producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output Waves of uniform shape and amplitude in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a specified time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by saidk first averaging circuit and for generating a control voltage functionally related to the integral of said first voltage over a selected time period, a plurality of utilization device actuating circuits, a control circuit capable of selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage, and means for indicating the output voltages of the respective averaging circuits.

4. A circuit of the character described including a pulse generating circuit capable of producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output Waves of uniform shape and amplitude in response to said pulses, an averaging circuit having an adjustable time constant for receiving the output of said timing circuit and for generating a control voltage functionally related to the period and rate of receipt of said output waves, said averaging circuit including means controlled by the frequency of said output waves for varying said time constant in different respects for increasing and decreasing frequency, a multiplicity of utilization device actuating circuits representative of different segments of a scale of magnitudes of said control voltage, and a control circuit for selectively actuating one of said utilization devices in accordance with the magnitude of said control voltage.

5. A circuit of the character described including a pulse generating circuit capable of producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, a first averaging circuit having a fixed time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a variable time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and for generating a control voltage functionally related to the integral of said first voltage over a selected time period, said second averaging circuit including means controlled by the frequency of said output waves for varying said variable time constant, a plurality of utilization device actuating circuits, and a control circuit for selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage.

6. A circuit of the character described including a pulse generating circuit capable of producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, a first averaging circuit having a fixed time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a variable time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and for generating a control voltage functionally related to the integral of said first voltage over a selected time period, said second averaging circuit including means controlled by the frequency of said output waves for varying said variable time constant, said time constant varying means including two parallel resistance and diode combinations, said diodes being connected in opposite polarity relationship, whereby said resistance diode circuits are utilized alternatively in said second averaging circuit depending upon the direction of the rate of change of said output voltage of said first averaging circuit, a plurality of utilization device actuating circuits, and a control circuit for selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage.

7. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude and of adjustable period in response to said pulses, an averaging circuit for receiving the output of said timing circuit and for generating a control voltage functionally related to the period of and rate of receipt of said output waves, a plurality of utilization device actuating circuits, and a control circuit capable of selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage, said control circuit including at least one twoposition relay having a relay coil, an adjustable source ofdirect current potential, a voltage divider circuit con- .'24 nected between said applied voltage and said source, and a vacuum tube with its plate circuit connected in series with said coil and being biased by the potential from said voltage divider circuit, whereby the conductance of said tube and thereby the energization of said relay coil is determined by said applied voltage.

8. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude and of adjustable period in response to said pulses, an averaging circuitA for receiving the output of said timing circuit and for generating a control voltage functionally related to the period of and rate of receipt of said output waves, a plurality of utilization device actuating circuits, and a control circuit capable of selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage, said control circuit including at least'one two-position relay having a relay coil, a first adjustable source of direct current potential, a first voltage divider circuit connected between said applied voltage and said first source, a second adjustable source of direct current potential less negative than said first source, a second voltage divider circuit connected between said applied voltage and said second source, and a vacuum tube with its plate circuit connected in series with said coil and being biased by the potential from said first voltage divider circuit when said tube is non-conducting and being biased by the potential from said second voltage divider circuit when said tube is conducting, whereby the conductance of said tube and thereby the energization of said relay coil is determined by said applied voltage, said biasing being controlled by said relay.

9. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, an averaging circuit having a fixed time constant for receiving the output of said timing circuit and for generating a voltage funcionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a variable time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a selected time period, a plurality of utilization device actuating circuits, and a control circuit capable of selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage, said control circuit including at least one twoposition relay having a relay coil, an adjustable source of direct current potential, a voltage divider circuit connected between said applied voltage and said source, and a vacuum tube with its plate circuit connected in series with said coil and being biased by the potential from said voltage divider circuit whereby the conductance of said tube and thereby the energization of said relay coil is determined by said applied voltage.

10. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a specified time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a selected time period, a plurality of utilization device actuating circuits, and a Acontrol circuit capable of selectively actuating one 'of said utilization circuits in accordance with the magnitude of said control voltage, said control circuit including at least one two-position relay having a relay coil, an adjustable source of direct current potential, a voltage divider circuit connected between said applied voltage and said source, a second adjustable source of direct current potential less negative than first source, a second voltage divider-'circuit connected between said applied voltage and said second source, and a vacuum tube with its plate circuit connected in series with said coil and being biased by the potential from said first voltage dividing circuit when said tube is non-conducting and being biased by the potential from said sceond voltage divider circuit when said tube is conducting, whereby the conductance of said tube and thereby the energization of said relay coil is determined by said applied voltage, said biasing being controlled by said relay.

ll. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a vacuum tubejmultivibrator timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, said multivibrator circuit including adjustable grid biasing means for varying the period of said output waves to compensate for known differences in the source of said external actuations, an

averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a control voltage functionally relatedl to the period of and rate of receipt of said output Waves, a multiplicity of utilization device actuating circuits representative of different segments of a scale of magnitudes of said control voltage, and a control circuit for selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage.

12. A circuit for selectively connecting one of a plurality of trafiic control `circuits in response to the traffic density as detected on one or more highway lanes, said circuit including a pulse generating circuit for producing pulses of uniform wave form in response to external actuation received from said detecting means, a vacuum tube multivibrator timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, said multivibrator circuit including capacitance for control of its timing, said multivibrator circuit also including adjustable grid biasing means for varying the period of said output waves to compensate for known differences in the calculated traffic density of said highway and switch means to vary the capacitance of said timing circuit reciprocally in accordance with the number of highway lanes being detected, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, Va second averaging circuit having a specii fied time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a selected time period, a plurality of utilization device actuating circuits, and a control circuit capable of selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage.

13. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform Wave form in response to random external actuation, a timing circuit for the generation of output l waves of uniform shape and amplitude and of predetermined period in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a control voltage functionally related to the period of and rate of receipt of said output waves, and means for adjusting said predetermined period to vary the ratio of said control voltage to the pulse rate. t

14. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, and a second averaging circuit having a specified time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a selected time period.

l5. A circuit of the character described, including a pulse generating circuit for producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude and of adjustable period in response to said pulses, an averaging circuit having a specified time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, and a second averaging circuit having` a specified time constant greater than the time constant of said first averaging vcircuit for receiving the voltage generated by saidV first averaging circuit and generating a control voltage functionally related to the integral of said first voltage over a a selected time period.

16. A circuit of the character described including a pulse generating circuit capable of producing pulses of uniform wave form in response to random external actuation, a timing'circuit for the generation of output waves of uniform shape and amplitude in response to said pulses and of frequency representative of the frequency of said pulses, and an averaging circuit having a variable time constant for receiving the output of said timing circuit and for generating a control voltage functionally related to the period and rate of receipt of said output waves over a 'scale of magnitudes of said control voltage, said averaging circuit including means controlled by the frequency of said output waves for varying said time constant in different respects for increasing and decreasing frequency respectively. g

17. A circuit of the character described including a pulse generating circuit capable of producing pulses of uniform wave form in response to random external actuation, a timing circuit for the generation of output waves of uniform shape and amplitude in response to said pulses, a first averaging circuit having a fixed time constant for receiving the output of said timing circuit and for generating a voltage functionally related to the period of and rate of receipt of said output waves, a second averaging circuit having a variable time constant greater than the time constant of said first averaging circuit for receiving the voltage generated by said first averaging circuit and for generating a control voltage functionally related to the integral of said first voltage over a selected time period, said averaging circuit including means lcontrolled by the relative output voltages of said averaging circuits for varying said variable time constant, a plurality of utilization device actuating circuits, and a control circuitfor selectively actuating one of said utilization circuits in accordance with the magnitude of said control voltage.

18. A circuit for receiving random pulses produced by traffic passing one or more points in accordance with the rate Vof flow of trafiic thereby, including means for receiving said pulses, means for integrating said pulses over an adjustable time period to derive an average pulse rate, means for indicating on a scale the pulse rate as so integrated by said last named means, means for varying the ratio of the indicationon such scale to the rate of receipt of input pulses to accommodate such scale to a wide range of rates of traffic flow and further means for varying the ratio of the indication on said scale to the rate of receipt -of input pulses to compensate for the number of said points connected to said receiving-means.

19. In a trac control apparatus-having a multiplicity of output circuits for controlling traffic in accordance with the rate of ow of traic per unit time, means for generating pulses from traffic passing one or more points, means for integrating such pulses by varying an electrical value in one direction progressively therefrom and varying said electrical value in the opposite direction between pulses over a period of time to provide an output voltage indicative of said integrated pulse rate and means for selectively operating one of said output circuits at a time in response to said voltage and in accordance with said voltage at such time.

20. An integrating circuit for averaging the duration and frequency of random input pulses, said circuit including switch means actuated by said pulses for controlling the charging of a condenser, an averaging circuit associated with said condenser to receive the output charge therefrom and to integrate same over a given time period, and means controlled by the output of said averaging circuit to vary the charging rate of said condenser whereby the charge on said condenser will produce an output from said averaging circuit having a linear relationship to the duration and frequency of said random input pulses.

2l. An integrating circuit for averaging the duration and frequency of random input pulses, said circuit including switch means actuated by said pulses for controlling the charging of a condenser, an averaging circuit associated with said condenser to receive the output charge therefrom and to integrate sarne over a given time period, and means controlled by the output of said averaging circuit to vary the charging rate of said condenser, said last .named means including a circuit for varying the charging potential across said condenser, whereby the charge on said condenser will produce an output from said averaging circuit having a linear relationship to the duration and frequency of said random input pulses.

22. In a traffic control apparatus, means for continuously accumulating a quantity in response to traic elements passing one or more points, means for continuously progressively reducing such accumulation at a predetermined time rate, a multiplicity of output circuits for controlling trac appropriate to various levels over a scale of rates of traic flow passing such point or points and means for selectively operating the respective output cirvalues of such quantity, means for individually adjusting the value for transfer from each of said output circuits to the next of said output circuits, and means interlocked with said last named means individually with respect to the transfer from each circuit to the next for individually adjusting the retransfer from said next circuit to the preceding circuit to establish a greater differential in value for the retransfer than for the initial transfer.

24. In a traffic indicating apparatus, input circuit means for receiving random pulses produced by traic passing one or more points, means for producing an output electrical value substantially representative of the average rate of said pulses received over a time period, means for indicating on a scale such output value in terms of rate of traic ow, means for varying the ratio of such output value and scale indication to the rate of pulses received, and means for adjusting such time period to provide a range of time base values for such averaging and for inversely corresponding rates of change of such output value and scale indication.

25. A combination as in claim 24, and including a multiplicity of output circuits corresponding to several segments of said scale of output values respectively, and means for selectively actuating said output circuits in accordance with said output value.

26. A combination as in claim 24, and including a multiplicity of output circuits corresponding to several segments of said scale of output values respectively, and means for selectively actuating at any one time the one of said output circuits corresponding to any particular segment of said scale in response to such output value being within a range of values substantially corresponding to such particular segment at substantially such one time.

27. A combination as in claim 26, and said time period adjusting means including two individually controllable adjusting means for setting such time period and means for selecting one ot' said two adjusting means for control of such time period when said output value is increasing and for selecting the other of said two adjusting means for control of such time period when said output value is decreasing, as a result of changing input pulse rate.

References Cited in the tile of this patent UNITED STATES PATENTS 1,593,993 Sprague July 27, 1926 1,823,739 Horton .r Sept. l5, 1931 1,944,723 Stirlen Jan. 23, 1934 2,170,160 Renshaw Aug. 22, 1939 2,176,742 La Pierre s Oct. 17, 1939 2,288,601 Barker July 7, 1942 2,295,534 Leathers Sept. l5, 1942 2,374,248 Tuttle Apr. 24, 1945 2,384,792 Brown Sept. 18, 1945 2,410,821 Hillman Nov. l2, 1946 42,448,113 Olafson Aug. 3l, 1948 2,506,368 Leonard May 2, 1950 2,594,276 Barker et al Apr. 29, 1952 2,751,574 Jeffers June 19, 1956

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