US2062616A - Electronic timer - Google Patents

Description

Dec. 1, 1936. I Q STANSBURY 2,062,616

ELECTRONIC TIMER Fild July 5, 1934 @MNMM Mm 5XMM$ $8 WXMW Patented @ec. l, 1936 Carroll Stansbury, Wanwatcsa, Wis to Cutler-Hammer, Ina, Miiwanhce Win, a corporation of Delaware Application July 5, E934 serial No. 333,721

6 Claims.

This invention relates to electron tube timing devices. An object of the invention is to provide for greater accuracy of the period during which current is supplied to an electric translating de- 5 vice especially where the period is of short duration.

Another object is to provide a system in which the period of current supply is accurately adjustable.

Another object is to provide a system in which the application of plate voltage to the electronic tube is prevented until the tube has reached its operating temperature.

Another object is to provide a system compris= 5 ing a gaseous electron tube through which current conduction when desired is initiated substantially at the beginning of the positive half cycle of the plate voltage.

Various other objects and advantages will hereinafter appear.

The system comprises a transformer i, having a primary winding I which is supplied with can rent from the terminals L and L of an alternating current circuit, and a secondary winding l Connected to the transformer secondary winding in a manner to be hereinafter described is a gas-= eous electron discharge tube 2 having a cathode 2*, algrid 2 an anode 2 and an auxiliary anode 2' The electron tube 2 is of the type disclosed 0 in my Patent No. 1,940,029.

A transformer 3 having a primary winding 8 which may be connected to any desired source of alternating current has a secondary winding 3 connected to the cathode 2 to supply heating current thereto. A relay 4 consisting of a bimetallic strip 4, a heater resistor 4 and a contact '4" controls the application of plate voltage to the tube 2. The heater resistor 4 is connected across part or all of the secondary winding l to obtain 0 heating current therefrom. The heater is mounted adjacent to the bimetallic strip 4 and aster a certain lapse of time it causes the strip to be deflected so as to make contact with the station my contact t. Connected between the plate 2 5 and the winding l is the coil. 5 of a relay 5 which has normally open contacts 5 and 5 and normally closed contacts 5 and 5. when the tube is conducting a current flows from one terminal oi the secondary winding l through the J bimetallic strip 4*, contact 4*, filament 2 plate 2, winding 5 back to the other terminal oi the winding I and thus relay 5 is energized and commutates the aforementionedcontacts. The sys tem also contains a relay 6 having a winding 8 and a normally closed contact 6", a relay I having winding l7 and a normally closed contact l and a relay [3 having winding 8 and a normally open contact 8 A normally open push button it is provided for the initiation of completion of the circuit to a. translating device which may he the magnet winding of a switch controlling the current supply to a consuming device or which may he the consuming device itself.

Connected to the grid 2 is one terminal of a resistor ii, the other terminal of which is connected to the auxiliary anode 2 and also to one terminal of a variable resistor H, the other terrninal of said latter resistor being connected to the normally closed contact 5. V The other side of said contact is connected to one terminal of a resistor is and also to one terminal of a condenser t 5, the other terminal of which is connected to the auxiliary anode 2 The first mentioned terminal oi condenser i5 is also connected to one terminal of an adjustable resistor it, the other terminal of which is connected to one terminal of the winding l The free terminal of the resister 83 is connected to contact 6 and also to the corrosion terminal of a condenser to and a resistor ii, the free ends of which are respectively connected. to the terminals of the winding l One terminal of the normally closed contacts S is connected to one terminal of the normally open contact 5 the other terminal of the latter iceing connected to the common point of the resis= tors i and and the condenser 95. The relay winding l. is connected across the secondary winding 3 so that it receives current when the cathode is energized. One side of the normally open contact ii is connected to the line 1?, the other side being connected to the winding 6 which, in turn, is connected in series with the push button ill to the line L One side of the normally closed contact 5 is connected to the common terminal of the normally open contact 3 and the cold 6 while the other side of said contact '5 is connected in series with the translating device 9 to the line L A resistor it] in series with a neon lamp i8 is connected in shunt contact 5' and the translating device 9. @nc side of the normally closed contact l is con nected to the common point of the contact 5 and the coil ti while the other side is connected through the coil 8 to the common terminal of the push button H8 and "the coil 6 The system operates as follows: y

it it is desired to supply power to the translating device e the lines L and L and the transformer winding 3 are energized. Current is then supplied through winding 3* to the cathode 2- to heat the latter. At the same time current is supplied to the heating resistor l and after a certain lapse of time the contact 4 is closed. As the grid 2 is at zero potential, current can flow from one terminal of the transformer winding I? through the bimetallic strip 4', contact 4, the cathode 2 anode 2 through the relay coil 5', back to the winding I, thus energizing relay 5.

When the relay 5 is energized, it closes its auxiliary contacts 5' and 5 The closure of contacts 5' permits the how of electrons from the cathode 2' to the grid 2'' and auxiliary anode 2 during the positive half cycle of the alternating voltage which is impressed upon the resistor IT by the'transformer winding I so that the condenser plate l5 which is in series with the grid is charged up to a negative potential with respect to the cathode corresponding to the peak value of the alternating current voltage drop across the resistor H, the negative current flowing from one terminal of the winding I through the thermal relay 4, cathode 2 anode 2 condenser l5, contacts 5 and 6 to the junction of the condenser l8 and the resistor H. The function of the condenser IB is to advance the phase of the voltage applied across the resistor H with reference to the anode voltage of the tube 2. Thus the condenser IS is charged. If now the push button I is operated, the relay 8 is energized by current flowing from line L through push button Ill, relay coil 8-, contact 1, contact to line I Circuit is also, completed from line L over push button III, relay coil 6, contact 5 to line Lflso that the normally closed contact 6" is opened. This disconnects the condenser l5 from the resistor I'I.

Prior to the opening of the contact 8' the tube 2 was conducting during each positive half cycle in spite of the fact that a negative charge accumulated on the plate li of the condenser I5. This charge in itself would have made the grid sufllciently negative to prevent the tube from conducting, but the alternating voltage drop across the resistor ll reduces this negative voltage during each positive half cycle to a value which is less negative than the critical grid voltage so that the tube actually does conduct. Fig. 2 illustrates this condition. Assuming that the cathode potential be zero, then the voltage E is substantially the voltage impressed by the transformer winding I upon the relay coil 5 and the anode circuit of the tube. Prior to the starting of a timing period the potential across the condenser l5 which has been charged as aforedescribed is 11 and superimposed to this condenser potential in the grid circuit is an alternating voltage E. As this is the voltage which charges up the condenser l5, its peak value is substantially equal and opposite to the charge of the condenser I5. As a result the potential of the grid 2 is reduced to approximately zero at substantially the beginning of the positive half cycle of the anode voltage on the tube so that the tube becomes conducting. After the contact 6'' has opened the alternating component of the potential of the condenser plate I5 and thus that or plate l5 relative to the potential of the cathode is determined by the ratio of the resistors l3 and N which are connected in parallel with the resistor II. This potential is designated as E in Fig. 2. It is evident that as illustrated this grid voltage is not any more suillciently high to make the tube conducting during the positive half cycle succeeding the opening of the contact IS. The interruption of current through the tube deenergizes the relay 5 and thus starts a timing period. In dropping back the relay closes a cir cuit for the condenser I! through the discharge resistance I! but the tube remains non-conducting until the condenser has discharged through said resistance I! to an amount which will reduce the potential E and thus the negative potential of the grid 2 so that the tube can again become conducting, that is, until the negative condenser voltage less the peak voltage of the drop through the resistor I4 is more positive than the critical voltage.

The phase shifting connection consisting of the condenser l6 and the resistor ll makes it possible to advance the phase of the voltages lil and/or E relative to the voltage E so that conduction starts substantially at the beginning of the positive half cycle instead of the middle of the positive half cycle u would be the case without any phase shifting connection. Thus a much more positive action of the relay 5 is obtained.

When the relay 5 is cle-energized while the relay 8 is energized as aforedescribed, a circuit is completed for the translating device 9. Thus the translating circuit is supplied with current for a definite period of time immediately upon closure of the push button l0. By varying the resistor l2 the discharge rate of condenser l5 may be variedand thus the period during which current is supplied to the translating device.

The use of the supplemental anode 2 greatly improves the accuracy of the timing circuit as it prevents the partial discharge of the condenser I5 through the are between the cathode and anode of the tube'2. As disclosed in my aforementioned application, the auxiliary anode does not tend to discharge during the positive half cycle, because it is out of the path of the arc, in contrast to the location of the grid. Thus the loss of charge due to this phenomenon is made up by the auxiliary anode 2 which during each positive half cycle recharges condenser plate ii' to the initial potential as outlined heretofore. The resistor II is of such value as to further prevent a substantial loss of charge of the condenser l5 between succeeding charging half cycles.

The transformer 3 has preferably a wide variation of voltage between no load and full load so that upon burning out of the cathode 2 the voltage on the secondary winding 8 rises. By adjusting therelay winding 1" so that it picks up and opens the contact l upon attainment of said higher voltage, the equipment is protected against faulty operation upon the burning out oi the cathode 2.

Instead of employing a tube with an auxiliary anode, as described, it is obvious that in its place a separate rectifier, having its anode connected to the circuit in place oi 2 and its cathode connected to the cathode 2 may be employed with the same results as heretofore described.

What I claim as new and desire to secure by Letters Patent is:

1. A gaseous electron discharge tube having a cathode, an anode, an auxiliary anode and a control electrode, means to impress an alternating potential on said cathode and anode, an energy storage circuit connected to said cathode and control electrode and adapted to impress upon said control electrode a unidirectional potential derived from said auxiliary anode to render said tube non-conducting during the positive half cycle of said alternating potential, and means to superimpose upon said unidirectional potential an alternating potential whose maximum amplitude coincides substantially with the beginning of the pos tive half cycle of the first named al- 15 ternating potential to render the tube conducting during said half cycle.

2. In combination with a translating device to be supplied with energy from a source for a given period, a gaseous electron discharge tube having a cathode, an anode, an auxiliary anode and a control electrode, means to connect said cathode and anode to said source and to impress an alternating potential thereupon, an adjustable electrostatic energy storage discharge circuit con-= nected to said cathode and control electrode and adapted to impress upon said control electrode a unidirectional potential derived from said auxiliary anode to render said tube non-conducting during thepositive half cycle of said alternating potential and to supply energy to said device during said given period, and means to superimpose upon said unidirectional potential an adjustable alternating potential, leading said first-mentioned alternating potential by substantially 90 degrees and adapted to render the tube conducting during said half cycle and to prevent current supply to said device.

3. In combination with a translating device to be supplied with energy from a source for a given period, a gaseous electron discharge tube having a cathode, an anode, an auxiliary anode and a control electrode, means to connectsaid cathode and anode to said source and to impress an alternating potential thereupon, an adjustable electrostatic energy storage discharge circuit connected to said electrodes and adapted to impress upon said control electrode a unidirectional potential derived from said auxiliary anode to render said tube non-conducting during the positive half cycle oi said alternating potential and to supply energy to said device during said given period, and means to superimpose upon said unidirectional potential an adjustable alternating potential, leading said first-mentioned alternating potential by substantially 90 degrees and adapted to render the tube conducting during said half cycle and to prevent current supply to said device, and means having a time function to delaythe connection of said first mentioned alternating potential to said tube for a given interval;

4. In combination, an alternating current source, a gaseous electron discharge tube having a cathode, an anode and .a control grid, means to connect said-cathode and anode in circuit with said source, a condenser connected to said grid,

means to charge-said condenser and impress a j go tential being oi a magnitude to render the tube conducting, means to reduce said alternating potential to render the tube non-conducting and adjustable means responsive to stoppage oi current flow in said tube to very said unidirectional potential to again render the tube conducting and to restore said unidirectional and superimposed potentials.

5. In combination with'a translating device to be supplied with energy for a given period, an alternating current source, a gaseous electron discharge tube having a cathode, an anode and a control grid and adapted to control the energy supply to said translating device, means to connect said cathode and anode in circuit with said source and said translating device, a condenser connected to said grid, means to charge said condenser and to impress a unidirectional potential upon said grid to maintain said tube non-conducting, means to superimpose upon said unidirectional potential an adjustable alternating potential leading the potential of said source by substantially 90, the maximum amplitude of said superimposed potential being of a magnitude to render the tube conducting which effects stoppage of current supply to said translating device, means to reduce-said superimposed alternating potential to render the tube non-conducting and "discharge tube having a cathode, an anode and a control grid and adapted to control the energy supply to said translating device, means to connect said cathode and anode in circuit with said source and said translating device, a condenser connected to said grid, means to charge said condenser and to impress a unidirectional potential upon said grid to maintain said tube non-conducting, means to superimpose upon said unidirectional potential an adjustable alternating potential leading the potential of said source by substantially 90, the maximum amplitude of said superimposed potential being of a magnitude to render the tube conducting which eilects stoppage of current supply to said translating device, means to reduce said superimposed alternating potential to render the tube non-conducting for a given period and to supply energy to said translating device and adjustable means responsive to the stoppage or current flow in said tube to vary said unidirectional potential toagain render the tube conducting and to restore said unidirectional and superimposed potentials.

' CARROLL STANSBURY.

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