US2635197A - Electrical apparatus - Google Patents

Description

Abril 14', 1953 c. A. ROUTLEDGE ET AL 2,635,197

ELECTRICAL APPARATUS Filed April 26, 1951 4 Sheets-Sheet l 3376545210XYZE8 Atfom April 1953 c. A. ROUTLEDGE ET AL 2,635,197

ELECTRICAL APPARATUS Filed April 26, 1951 4 Sheets-Sheet 2 RIOCL I RSbNQ Inventors O/R/sToP/IER fink/Aw Khan/5M5 filer/2r Job Iv KHW v Attorney April 1953 c. A. ROUTLEDGE ET AL 2,635,197

ELECTRICAL. APPARATUS Filed April 26, 1951 4 Sheets-Sheet 5 637 fi N fii Fla-4. CH I I kw H Raqafb 5 d.

Inventors (HRISI'OPMER flmw/v Roar: met

0485M dbl/1v KEEN April 1953 c. A. ROUTLEDGE ET AL 2,635,197

ELECTRICAL APPARATUS Filed April 26, 1951 4 Sheets-Sheet 4 ney Patented Apr. 14, 1953 ELECTRICAL APPARATUS Christopher Adrian Routledge, Walsworth,

Hitchin, and Albert John Keen, Lctchworth, England, assignors to The British Tabulating Machine Company LimitecL London, England,

a British company Application April 26, 1951, Serial No. 223,002 In Great Britain May 24, 1950 8 Claims. 1,

This invention relates to operating circuits for relays and more particularly, but not exclusively, to relay circuits suitable for use in accounting machinery;

It is often desirable to arrange that the armature of a relay should not be operated until after an operaitng voltage impulse applied to the coil of the relay has ceased, as for example in the case where the relay coil is connected to the voltage source through its own contacts. In order to obtain this delayed operation, it is known to employ electrical slugging of the relay, or auxiliary delay circuits employing a second relay or a thermionic valve but if these are to allow operation of the relay armature'immediately after the cessation of the operating impulse; it is necessary that the duration of the operating impulse be maintained equal to the predetermined delay provided by the relay.

Accordingly, it is an object of the present invention to provide an electrical operating circuit for a relay, such that the relay armature is not operated until immediately after the operating impulse has ceased, this result being obtained even when the'duration of theoperating impulse varies between very Wide limits.

It is a further object of the invention to provide a simplified electricalcircuitfor delaying the operation of a relay armature for a time closely approximating the duration of the operating impulse, the said circuit including a condenser which is charged by the operating impulse and which discharges through the relay coil to effect delayed operation of the relay armature, diiierent charging and discharging paths forthe condenser being provided by the action of arectifier, that is to say an asymmetrically conducting resistance, such as a metal dry-plate or crystal rectifier.

It is still another object of the invention to combine a plurality of delayed operation relays to form a relay counter, thereby making the counter tolerant of wide variations in the duration of the operating impulses.

According to the invention, a-circuit for obtaining delayed operation of a relay comprises an 2 discharging operates the relay upon termination of the said voltage, the rectifier then acting as a high resistance shunt.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1- shows the circuit of a double acting relay arranged for delayed operation.

Figure 2 is a cam timing diagram relating to Figure 3.

Figure 3 shows one denomination of a decimal adding relay counter.

Figure 4 shows two denominations of a decimal adding and subtracting relay counter.

Figure 5 is a cam timing diagram relating to Figure 4.

Relay Rl (Figure l) is of the double acting type, that is to say, when pick-up coil RIP is energized, the relay armature is shifted to the operated position and retained in that position even'vvhen the pick-up coil is ole-energized. The armature is returned to the normal position by energization of unlatching coil L. This action may be obtained in several known Ways. For example, the armature may be so mounted that a toggle actionisobtained with the two extreme positions of the armature being conditions of stability. Alternatively, the armature may engage a mechanical latch in the operated position, this latch being disengaged by energizing the coil L, the armature being returned under spring pressure tothe normal position.

InFigure 1 the relay RI is shown with the a mature in normal or unoperated position. When switch 3" is closed, a circuit will be made from negative supply line i, switch 3, contacts Rla, (normal), resistor 4, to positive supply line 2. Condenser 5 is in series With the combination of rectifier 8 and relay coil P in parallel. This network is across the resistor 4" andin consequence, when switch 3is closed, the condenser Will begin toch'arge to the potential across the resistor. rhe rectifier resistance in the forward direction is low compared with the coil resistance so that the greater part of the condenser charging current flows-through the rectifier and only a small fraction through the coil P, this being insufficient to cause operation of the relay. If the switch 3 is opened when the condenser 5 has become fully charged, then the condenser will discharge through resistor 4 andre'ctifier 6 in' parallel with coil P. The back resistance of the rectifier'is high compared'with the coil resistance, so that the greater part of the discharge current flows through coil '1. This current is suificient'tocause attraction of the armature towards coil P so that contacts RIa will be shifted and retained in the shifted position by the normal mechanical locking action of the relay.

When switch 3 is again closed, a circuit will be made from line I, switch 3, contacts Rla (shifted), resistor l to line 2, and condenser 8 will charge through rectifier 9. When the switch is opened, condenser 8 will discharge through the unlatching coil L in the same manner as described for coil P, thus causing the armature to move back to the normal position where it will again be mechanically locked.

It will be appreciated that the relay is operated not when the operating voltage is applied and charges the condenser, but after the operat-' ing voltage is removed and the condenser discharges. In the particular circuit shown, this has the advantage both of preventing arcing at the contacts RIa, since there is no current flowing in this circuit at the time, and also of avoiding the necessity for special forms of make before break contact which would be necessary if the relay operated whilst the operating impulse was still applied.

Although the example considered was a double acting relay, it will be appreciated that the same method of delay is of general application to relays of other types.

It has been found that in the case of a relay requiring an operating current of approximately 60 milliamps, a condenser of .3 microfarad and a resistance of 1500 ohms provided satisfactory operation. However, these values are given by way of example only, since the optimum values will depend upon the operating current and coil resistance of the particular relay and the voltage employed.

A plurality of the relay units operating in the manner described may be connected together in such a way as to form a relay impulse counter, the facility of being able to feed current to the relays through their own contacts without incurring arcing, enabling a very simple circuit to be used. In Figure 3 is shown the circuit of one denomination of such a counter for operation in the decimal system and intended particularly for operation by impulses derived from the sensing of punched record cards. Various methods of sensing such cards are known to produce an impulse at a time representative of the digit position sensed, as indicated by the timing chart (Figure 2) showing the digit index point timings from to 9, together with index point positions corresponding to the so-called X and Y positions on the card and index points Z and E corresponding to the interval between the sensing of two successive cards.

An intermediate denomination, for example, the tens denomination of the counter is shown in Figure 3. Essentially, each denomination of the counter is similar and therefore only a single denomination will be described in detail. The denomination comprises six relay units, an accept relay R2 controlling entry to the denomination, four relays R3, R4, R5 and R6, representing respectively the digital values 1, 2, 4 and 8, and a carry registering relay Ri.

In order to read a value into the counter denomination, a plug connection is made between socket I2 and the appropriate column of the card sensing device. It will be assumed, by way of example, that the digit 9 is recorded in this particular column. At 9 time (Figure 2) an impulse will be produced by the sensing of the 9 hole and the circuit will be completed from the sensing device through the plug connection, socket I2, contacts RIGa, RSa, RS'a, resistor 2|, to the positive side II of the supply line. The condenser 23 will be charged through rectifier 22 and when the impulse ceases, this condenser will discharge through the pick up coil RZP to operate and set relay R2, in the manner already described. Thus contact R2a is closed and will remain closed due to the mechanical latchin until coil RZL is energized.

At 8 time, a circuit will be made from line iii, cam contacts C5 closed (Figures 2 and 3), contacts R2a (shifted), contacts R30, resistance 2 to line H. When the impulse ceases, because C5 contacts open, condenser 25 will discharge to operate relay R3, thus registering 1.

Through cam contacts C5 and contacts RZa similar circuits will be set up to energize, after the impulse ceases, one or more of the relay coils as follows:

At 7 time from contacts R2c, contacts R2a (shifted), resistor 29 to line II to reset relay R3, and a parallel circuit from contacts R3a, contacts RISa, contacts Rea, resistor 2-8 to line II set relay Rd and register 2.

At 6 time from contacts RZa, contacts R3a (normal), resistor as to line II to set relay R3 and register a total of 3.

At 5 time from contacts R2a, contacts R3a (shifted), contacts Rfia, contacts R la (shifted), contacts R5a, resistor 2'! to line II to set relay R5 and register 4 and branch circuits from contacts R311 and Ria to reset relays R3 and R4.

At "4 time relay R3 will be energized, as at 8 time, to register 5.

At 3 time, relay R4 will be energized and R3 reset, as at 7 time, to register 6.

At "2 time relay R3 will be energized, as at 6 time, to register 7.

At 1 time from contacts R2a, contacts R3a (shifted), contacts Rta, contacts R ia (shifted). contacts R512 (shifted), resistor 28 to line II to energize relay R6 and register 8, and branch circuits from contacts Rta, R441, R511, to reset relays R3, R4 and R5.

At "0 time relay R3 will be energized, as at 8 time, to register 9. Also, before 0 time, cam contacts C4 close (Figure 2) to energize relay RI3, so that at 0 time a circuit is made from line If cam contacts C5, contacts RI3a (closed), contacts R812, resistor 34, to line I I to reset relay R2.

Thus after 0 time, a count of nine is registered by relays R3 and R6 being operated, and relay R2 has been reset.

If the next card to be sensed contains the value two in this particular column, then relay R2 will be energized at 2 time through a circuit already described. At 1 time a circuit will be made from line It, cam contacts C5, contacts R2a (shifted), contacts Rta (shifted), contacts RSa (shifted), contacts R91), pickup coil R'IP, to line II, to energize the carry relay R'I. At the same time branch circuits from contacts RM and RM effect the resetting of relays R3 and R6. At 0 time relay R3 is energized and relay R2 reset through circuits already described.

At X time, cam C3 closes and a circuit is made from line lil, cam contacts C3, contacts R'Ia (closed), contacts R2a to line 2 ii. Contacts R2'a correspond in the next higher denomination, to contacts R211 in the present denomination, so that line 29 is connected to the value I relay in the higher denomination and an impulse on this line will cause an entry of one, thus correctly entering through resistor 33; eifects the resetting of relay Rlzwhen contacts C3.;cpen.

ContactsRT'aare operated by the carry. relay in the next. lower denomination, so. that if this, relay-had been operated then-1 an entry ofzone. would-have been made into. the present.denomina-. tionalsocn theclosure-otC3 contacts. The comparatively long closure of; contacts C3; together with the immediate operation; of relay coil R'IP which. has nocondenser, delay circuit. enables.

longcarries, that is, successive carriesoccurring;

when acne is. added *othe lowest of; several de.-. nominations all standing. at. nine; to be success.- fully dealtwith,

Adescription hasbeen given. of how two digits;

are added; itwill now beexplained how one digit; maybe subtracted. from another... To. condition. the counter for subtraction, relay'R8 is: energized, by connectingsccket. l5fto..a suitable source. of potential;

It will be assumed thatthe value 9, has already been registered in. the denomination. and thatpthe value 2 is tobe subtracted. At 9. -time a circuit;

will be madefrom line H], cam contactsCZ, cone tacts R80; (shifted), resistor; 21,. to line, H. Relay R2 will be energized thereby, so that; from 8 time to 2time, impulses will be fed to the count.- er denomination andwill' add as already described, so that after 2? time the denomination will register 6 sincesevenadditional: pulses havebeenem. tered and the carry relay R1; willhavebeenenergized. At 2 time, the impulse from the card sensing has a circuitv from socket l2, contacts. Rita, contacts RBI). (shifted), resistor 34, to line H, to. reset relay R2. after 2 time are applied to the counter through cam contacts C5, since oontactsRZa are now open.

In other denominations which are initially at.

zero and to. which no cardsensing impulses are applied, the full number ofnineimpulses are applied and these denominations. will therefore all register 9. At.X timecam contact C3- will; close to reset the carry relay and enter the carry. Since all denominations. except the one under consideration are registeringfl the carry due to.

relay R! being setwill successiyely-gzeroise. these;

denominations and finally. the carry relayof the highest. denomination will be operated. The; con..- tact of this relay instead of: being. connected to a, contact corresponding .toRZa is connected to av plug socket: This plug socket isv connected by a plug wire to a socket connected to the. on side-v of the contact corresponding to R211 in the lowest. denomination of the counter, for whichthere will be no contact corresponding. to Rla, In this manner the carry from the highest. denomination will be entered into. the lowest denomination of the counter, constituting. the sc-called elusive. 1 entry. The lowest denomination will be zeroised and carry to the tens denomination which is already registeringfi, so. that a. final. registration of I is obtained, as they result of subtracting 2 from 9 in this denomination. If the number to besubtracted is larger than the number registered, then the result will be registeredinthe usual manner as a 9s complement.

In order tovread out the valueregisteredin the counter it is necessary to energize relays R9 and RH by connecting sockets IS and I8 to a suitable source of potential. When camcontacts Cl make at E time (Figure 2). a circuitwill bemade from line l0, cam contacts Cl, contacts R911 (shifted), resistor 2.! to line. H to energize coil RlP. whenthe cam contacts reopen. Wit-hrelay. R2 set, at "93.

'Ihusv no; further pulses time of: the nexticyclean. impulse; will. be fedto thecounter viascamcontacts G5 and contacts Ric;

(shifted). to. addone. to; the counter registration. Similarlyimpulses will-be applied at all theindex.

- points down toandincluding 0,. so.- that atotalg.

oftenimpulses are, added.

Let it be assumed that the initial registration. in the. denomination i.s '7. Then. at...7. time,.the

denomination; will already-hare. received two im pulses and willtherefore-be registering so that a circuit will be made from .line H1, cam contacts C5, contacts R211 (shifted), contacts Ritav (shifted) contacts R641; (shifted) contacts. R922. (shifted), contact R1 Ila. (shifted); to. socket l3, from which a plug connection may be made-todirect. the '7. timed impulse to anothercounteiza; printing mechanisrnetc.v Branchcircuits: will effect the resetting of relaysR3. and RB..

The remainingseyen impulses produced; by C5. duringthis cycle produce a registration. of seven in the denomination and since the, shifting of'contacts RSb-preyentedthe operation of the carry. ,relay R! when the countwent from nine to zero at theend of the readout cycla the value-has. been read out: and the denomination :returned to the original registration.

In order to zeroise the counter, relay. RIZ .is energized bysuitable connectionfrom socket. l9 to a potential source so that contacts R|2a to Rl2d are closed, causing theenergization'oi-relays. R8, R9, RH} and RH throughxcircuits iromisocket i9; As in the caseof readoutv the closing of cam contacts Cl willcause the-settingof relay R2 and the consequent entry of impulses when C5 closes. However, assuming the initial. registration is 7, at '7 time two further pulses will have been counted, making the registrationiiiandthere will be a circuit from line H), cam contacts C5, contacts R2a (shifted) contacts R311 (shifted), contacts RSa (shifted) contacts R912 (shifted), con tacts Ri la (shifted), contacts Rlfla (shifted), contacts R81) (shifted) ,resistor 3 lz-to-line II, to effect the resetting of relay R2. Since relay R2 is reset no further impulses will be applied to the denomination and relays R3 and R6 will have been reset by-branch circuits from the circuit described so that the counter remains at. zero. By making a connection'to socket I 3, a read out of value may be obtained atv the same-time as zeroising takes place.

Although-the counterhas been described as operating in the decimal notation, it may readily be adapted-for other notations.

In order to count in du'odecima-l, the circuit to the carry relay R1 through the contacts Rfia must be prepared at eleven instead of nine. In this case the centre contact R4ai is connected to the off side of contact'R3a and contact RSa is connected between contacts R4a'and R5151 instead of between contact R3a andRla.

If contact Rfia is connectedin the same manner as contact R511, then'the counter-will operate in radix sixteen.

If relay RIO is energized by=a connection to socket i1 and a plug. connection made to socket M from another counter, thenread in from the second countermay-be made in" the same mannor as is effective when reading. from a card to socket l2.

It is also possible to construct a counter operating in a code other thani, 2,4, 8. In Figure 4 are shown two denominations of an adding and subtracting counter; using the code-1, 2, 2, 4. The. method of subtraction is also a modificaq tion of that shown in Figure -3.' In this latter circuit subtraction is effected by operating the accept relay R2 at 9 time and resetting it when the digit impulse occurs, thus entering the complement of the number to be subtracted. In the modified form of Figure 4 the counter is stepped backwards when subtraction is carried out.

In Figure 4 each of the blocks represents a complete relay unit with the associated resistors, condensers and rectifiers, except for relays RI9 and R25 which are double acting relays without any delay network. In each case, the left hand lead is connected to the pick up coil P and the right hand lead to the unlatching coil L.

Relays Rid and R20 are the accept relays for the units and tens denominations respectively. Relays RI5 to R18 and RZI to R24 represent the digital values 1, 2, 2, 4. respectively in the units and ten denominations. Relays RIS and R25 are the carry relays.

Adding proceeds in a similar way to that already explained. For example, if 7 is to be entered with the counter initially at zero, then the impulse from the card sensing will set up relay RI4 at the end of 7 time via socket I2 and contacts R2'Ia.

At 6 time, cam contacts C5 (Figures 2 and 4), will provide an impulse to set relay RI5 to register 1 through the circuit from line It, cam contacts C5 (shifted), contacts Rita (shifted), contacts Rita, relay RI5 to line Ii, the actual setting taking place after the end of the impulse.

At succeeding digit times the impulses from cam contacts C5 will set and reset the relays as indicated below.

At 5 time relay RIG is set through contacts Rita (shifted), contacts R29a and contacts RIBa, whilst relay RI5 is reset through contacts RIBa (shifted).

At 4 time relay RI5 is set again through contacts RI5a.

At 3 time relay RII is set through contacts RISa (shifted), contacts R2902, contacts RIGa (shifted), contacts R29d, contacts Rlla and contacts RZQe. Relay RI 5 is reset as before.

At 2 time relay RIE is set again through contacts RIEa.

At 1 time relay RI8 is set through contacts Rita (shifted), contacts R2911, contacts RIGa (shifted), contacts R291), contacts RI la (shifted), contacts R291 and contacts RiSa. Relay RIB is reset by a branch circuit from contacts R'29f through contacts R290 and relay RIE is reset as before.

At time relay RI is set again, so that relays RI5, RI! and RIB are now set giving a registration of 7.

The contacts controlled by relay R29 are operated when subtraction is to be effected and they are identical in each denomination of the counter.

If a second number, say 5, is now added into the units denomination, then after two impulses the counter will register nine with all four relays RI5, RIS, RH and RM energized. At the third impulse there will be a circuit from line It, cam contacts C5, contacts Rita (shifted), contacts RI5a (shifted), contacts R2911, contacts Rita (shifted), contacts REM, contacts Rl'la (shifted), contacts R29f contacts Rlfla (shifted), contacts RZQhQcontacts R210, contacts R2611, pickup coil of carry relay R!!! to line I I. Branch circuits to the unlatching coils of relays RI 5, RI 6, RH, and RIB effect their resetting.

8 The fourth and fifth impulses register two in the units denomination. After Z time, cam contacts CII] close (Figures 4 and 5), to energize relay R28. At E time, cam contacts C8 close I to make a circuit from line It, cam contacts C8,

contacts RIQa (shifted), contacts R2iia, contacts RZIa, pickup coil of relay RZI to line II, to enter the carry into the tens denomination and provide a final registration of twelve.

In order to effect subtraction, relay R29 is energized by connecting plug socket 31 to a suitable source of potential. This shifts all the related contacts and changes the connections to the counting relays in such a way that they are operated to reduce the value already registered. For example, suppose seven is registered in the units denomination and three is to be subtracted. The first impulse from cam contacts C5 will proceed via contacts RI Ia (shifted), contacts RI5a. (shifted), unlatching coil of relay RI5, to line II to reset relay RI5 and leave a registration of six.

At 1 time, there will be a circuit for the second impulse from contacts RI ia, contacts RI5a, contacts RZQa (shifted), contacts Rita, contacts R291) (shifted), contacts RI'Ia (shifted), contacts R25) (shifted), unlatching coil of relay RII to line H. Consequently, a registration of five is obtained with relays R55 and RIB set.

At 0 time, there will be a circuit similar to that for the first impulse to reset relay RI5 and leave a registration of four.

Carry between denominations is effected in the same way as during adding, but since the counter is set for subtraction, the carry will reduce the registration of the denomination into which it is entered by one. The carry connection from the tens carry relay contact R25a is connected back to the units accept relay contact RI la to provide for entry of the elusive 1 occurring when the registration of the highest denomination goes through zero.

The method of reading out the actual value registered in the counter is the same as that previously described. Relay R2! is energized by a connection to plug socket 31 and before 9 time the accept relays are set through contacts R2'Ia and R2lb by the closure of cam contacts 01 (Figures 4 and 5). Thus, ten impulses are applied to each denomination of the counter from cam contacts C5 to provide a timed impulse, from the line normally operating the carry circuit, through contacts R270 (shifted), to the socket l3.

This circuit is particularly useful in certain applications as it allows the reading out of the complement of the value registered, a facility not available with the previously described circuit. The relay R2'l is energized as before, but the subtract relay R29 is also energized. In consequence, the ten impulses will now be subtracted from each denominational registration and the timed output impulse will occur when the registration passes from zero to nine. Thus if the registration were seven in a particular denomination, then at 3 time, seven impulses would have been entered and the registration would have changed to zero. At 2 time, the registration would pass to nine and an impulse would be produoed at the socket It, being the correctly timed readout of the complement of the value registered. The remaining two impulses would return the registration to seven.

Zeroising of the counter concurrently with readout may be obtained by energizing relay R28 by a connection to socket 35, and operates in the manner previously described. However, if the counter is reading out the complement of the registered value, the read out impuls occurs when the counter passes from zero to nine and consequently each denomination would be set to nine. If this condition is set up, then relays R38? and R3 IP will be energized, being in parallel with relays R28 and R29. Contacts R3011 and R3 I a close to provide a circuit to the hold coils R30H and RSIH through cam contacts CH (Figures 4 and 5). When contacts C8 close, a circuit will be made through contacts R392; and R311) (shifted) and contacts Rl la to reset the relays oi the lowest denomination. The circuit will also extend through contacts RZBa (shifted) and contacts Rlfla to the next denomination to reset the relays of that denomination. If further denominations were employed, similar circuits would exist for resetting these from nine to zero.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodlment, it will be understood that various omissions and substitutions and chan es in the form and details of the device illustrated and in its operation may be made by those skilled in the art without de arting from the s irit of the invention. It is the intention, therefore. to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In an electrical s stem. the combination of an electroma netic re ay ha in a windin a rectifier in arallel with said wind n a capacitor in series with said parallel-connected rela windins! and rectifier, and a resistor in para lel with the capacitor in series with the relay w nding and rectifier, and a current so rce for supnlyin current to char e said capacitor through said rectifier in the for ard direction thereof.

2. Tn an electr cal s stem. the combinat on of an electroma netic r a ha ing a win in a rect er o fering a relative lo res stance to currents in one d rect on theret r u h and a rel ti e y h h re istance. to currents in N10 onpos te d rect on ther thron h. sa d r ctifier bein connected in parallel ith t e win in of said rela a ca acitor in series with said parallelconnected re ay win i g and rectifier, and a resistor n parall l with the ca acitor in series with the re a windin and rectifie nrrent nn'rce for snnnlvinq pnrr nt to char e said nana it tlwrmwh aid win n and a so through said rectifier in the one direction w ereby sai rectifier Ofie'rs a low r stance s unt to sa d w ndin to prohi it oneration of sa d rela and means for dis nn t n sa so rce t ermit said ca nacitor tn dischar e thr h s id ndin and a so thro 'h aid rectifier in the said e a; fli tion hereb aid r ctifier offers a hi h resistance shunt to said winding to permit said relay to operate.

3. A combination as claimed in claim 2, and comprising contacts on said relay, said contacts being included in the charging circuit for said capacitor.

4. In an electrical system, the combination of an electromagnetic relay having two windings thereon, contacts on said relay adapted to be moved in one direction by energization of one of said windings and to be moved in the opposite direction by enereization of the other 01 said windings two rectifiers connected each in parallel with one of said windings, two capacitors each connected in series with one winding and a rectifier in parallel therewith, two resistors each connected one in parallel with one of said condensers in series with a relay winding and the rectifier in parallel therewith and means for supplying a charging current to one of said capacitors through contacts of said relay whereby on cessation of supply of said current said contacts are moved to prepare a charging circuit for the other of said capacitors.

5. A voltage impulse counter comprising a plurality of chain-connected stages, each stage comprising an electromagnetic relay having two windings thereon, contacts on said relay adapted to be moved in one direction by energization of one of said windings and to be moved in the opposite direction by energization of the other of said windings two rectifiers connected each in parallel with a different one of said windings, two capacitors each connected in series with a different one of said windings and a rectifier in paral-- lel therewith, two resistors each connected one in parallel with one of said condensers in series with a relay winding and the rectifier in parallel therewith a current source, circuit means including the contacts of a relay of one stage for supplying charging current for a capacitor of that stage, and further circuit means including contacts of the relay of that stage for supplying charging current for a capacitor of a succeeding stage,

6. A voltage im ulse counter as claimed in cla m 5, wherein said sta es correspond to the values 1, 2, 4 and 8 respectively, and comprising means for causin the relay of the stage correspondin to value 8 to be moved in one direction after 8 imnnlses and to be moved in the reverse direction after two further im ulses whereby said counter o erates as a decimal counter.

'7. A voltage impulse counter as claimed in claim 5. wherein said sta es correspond to the values 1, 2. 2. and 4 respectively, and comprising a carr registering relay. wherein a first impulse moves the contacts of the relay of the stage value 1 in a first irect on. a second impulse moves the contacts of the relay of the stage value 1 in the o pos te d rection and moves the contacts of the re av of the first sta e value 2 in the first direction. a fourth impul e moves the contacts of the relay of the second stage value 2 in the first direction without moving the contacts of the relay of the first stage value 2, a s xth impu se moves the contacts of the relay of the stage value 4 in the fi st direction and moves the contacts of the rela in the first sta e of value 2 in the o posite direction and the 10th impulse moves the contacts of the relays of the four sta es in the o posite direction and operates the carry-re istering rela 8. A volta e im ulse counter as claimed in claim 5. and comprising sw tchin means associat d with the contacts or said relays for contro ling at will the order of movement of the contacts of said. relays, whereby said counter can be made to add or subtract at will.

CHRTSTOPHER, ADRIAN ROUTLEDGE. ALBERT JOHN KEEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,168,198 Frink Aug. 1, 1939 2,342.821 Reagan Feb. 29, 1944 2,427,751 Snyder Sept. 23, 1947 2.439.405 Zierdt Apr. 12, 1948 2,538,789 Maynard Jan. 23, 1951

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