US1917418A - Electric delay circuits - Google Patents

Description

July 11, 1933. M ALMQUIST r AL 1,917,418

ELECTRIC DELAY CIRCUITS I Filed June 18,. 1931 IIHIIIIFWWW I HP WFzQQ.

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This invention relates to electrical circuits and more particularly to improved. arrangements for introducing a. delay or time lag in the operation of elements included in such circuits. f

In electrical systems such for exsrnple, es in a. telephone plsnt, it is Ir uently necessery to have apparatus or circuits which will introduce appreciable time intervels between the operation or: one part of e. circuit and en- Hieretoiore, this has ,heen plished in verious ways, such hy relayswhich have heen designed to he slow-opera e. ing or slow-releesing, and by circuits which depend upon the time required to charge or discharge condensers.- With the condenser errsngeinents more uniform delsys may he obtained then with releys clone, hut thesecir- .cuits have the disadvantage that the especities required hecoroe rether lsrge for the long or time intervals due to the fee-u, that the charging resistance which may he used is lino. ited to e. value which will give sufiicient cur rent to operate the controlled reley with the battery voltage evsilsble. In other words, the time interval between the cperetiou of the controlling relay and the controlled relay, is proportional to the product of the charging resistance and the capacity. The time inter val also depends upon the adjustment or? the controlled relay since this adjustment deter .mines the magnitude to which the current through the reley'must build up in order to cause its operation.

The arrangements of the invention have been provided to do cwcy'with the above disadvantages of prior arrangements. In the arrangements of the invention a gas filled tube is added to the circuit of the controlled relay. The gaseous'contont of the tube may,

for example, be neon. Tubes of this type are re uire little or no maintenance, and can be made quite uniform in their break down voltage. The timing in a circuit of this type do ends upon the time required to charge t econdenser to a. potential suficient tocause the tube to break down,'and is not dependent upon the adjustment of the controlledrelay. When the tube breaks down, its. impedance drops to a low; value and per- 1981. Sorrel Bo.

Inits the condenser to discharge through it and operate the controlled relay. Tnis relay, in addition to giving an indication to external circuit to which it is connected, short-circuits the tuhc and changes the vs hrs of the charging resistance, end thus lowers the circuit resistance to 9. point Where suifr cient current WiH to keep the controlled operated. Under these conditions the ndenser need only he of suficicnt cepscitv to give it discharge current which is enough to operate the controlled relsy o-= Fig.1 is c circuit dingo in illustrating arrangements or the prior art. Fig. '2is a circuit diagram embodying the crrengements oi? the invention. Fig. 3 is c. modification of the arrangements of 2. Similar reference characters hsvebeeu' heed to denote like parts insll of the figures.

In Fig. l are shown arrangements of the prior art in which e. relay A controls the circuit of a reloy B. This circuit includes 2. battery and a charging resistance R. A. condenser C is bridged from this circuit to ground. When the relay A operates, the condenser C Wlll charge, and as soon as the potential across the condenser has become sufiicicnt to cause the current through relay B to reach the. required amount, relay B will opcrate. The resistance R 1s provided in the circuit to raise the impedance of the relay.

circuit to approximately that of R. The resistance R is provided to limit the rate of discharge of the condenser 0, when the relay A releases. In this circuit the time'im teryal betweentbe operation of relays A and B Is pro ortional to the product of the resistance and the capacity C. The time indown voltage.

invention is shown in terval also depends upon the adjustment of relayB since this adjustment determmes the magnitude to which the current through the rela must build up in order to cause its operation. Such a circuit also has the dreadvantage that the capacity, such as C, required becomes rather lar e for the lon er time intervals due to the act that the c argmg resistance R which may be used is limited to a value which will give suflicient current to operate rela B with the battery voltage available. known in the prior art.

To eliminate the disadvanta es of the above circuit, the arrangements 0 the invention as shown in Fig. 2 are provided. In these arran ements a two-electrode as filled tube T is a ded to the circuit. Suc a tube would preferably be of the cold cathode type,

be made quite uniform in its break The gaseous content might, for example, be neon. Timin in this circuit depends upon the time required-to charge the condenser to a otential suflicient to cause the tube to break own, and is not de ndent upon the adjustment of rela B. en the tube breaks down, its impe ance drops to a low value and permits the condenser to discharge throu h it and operate relay B. This relay, in ad ition to givin an indication to the external circuit to whic it 1s connected, short-circuits the tube and resistance R,, and thus lowers the circuit resistance to a point where 'sufiicient current will flow to keep relay B 0 rated. Resistance R which may be who ly or partly included in the resistance of the winding of relay B, is required to slow down the dischargin of the condenser through the relay B su ciently to give it time to 0 rate. Resistance R, serves to limit the disc arge current of the condenser 0 upon the release of relay A, as in the arrangements of the prior art. The condenser C needs only to be .of suflicient capacityto give a discharge current which is large enough to operate relay B momentarily, and with this valueestablished the timing may be changed by varying the resistance R,. It is pointed outthat these conditions are the reverse of those used in the arrangements of the prior art referred to. The arrangements of Fig. 2 might be-slightly modified if desied. For example, it would not be necessary to short-circuit the tube when relay B operates if the values of resistances R, R and R, are chosen so that the short-circuiting of resistance R, will lower the circuit impedance sufiiciently to maintain the discharge through the tube. These arrangements would uire fewer contacts on the relay B and woul simplify obtaining a suitable relay for the purpose.

A modification of the arrangements of the 3. In this arent there is used a rec-electrode gins tube T. The gaseous content mig t,

and could ran he above arrangements are well for example, be neon. The operation is similar to that of the arran ements of Fig. 2, in that the time interva between the operation of relay A and relay B de ends u on the time required to charge con enser (I to a potential suflicient to cause the tube T to break down. It differs from the arrangements of Fig. 2, however, in that relay B is operated by the cathode to anode current which is set up when the tube breaks down, instead of b the discharge of condenser C. The rid o the gas filled tube '1" is connec to the condenser G and, de nding upon the time interval r 'red or the charging of the condenser will have its potential chan ed sutliciently to cause the tube to break own. The cathode to anode current will hold the relay B operated until the cathode to anode circuit is opened by the release of relay-A, since in this kind of tube the grid loses control of the action as "soon as the tube breaks down, and the cathode to anode current cannot be stopped except by removing the energizing potential. T is, of course, makes it unnecessary to provide contacts on relay B to reduce the resistance of the circuit or short-circuit the tube in order to obtain suflicient current to hold relay B operated. The current through relay B is limited by the voltage of the battery B,, and the resistance of the tube after break down, and the resistance R which may be wholly or partly included in the resistance of the winding of relay B. Resistance R and condenser G, form the timin cir- 1 cuit, and batte B, furnishes the additional voltage require by the rid in order to make the tube break down. esistance R is provided to limit interaction between the rid and anode, and resistance R, is provide% to limit the discharge current of the condenser C when relay A releases. When relay A o erates the voltages of batteries B, and B, will be applied through resistance R and over the lower make contact of relay A to the condenserC and will char e it. W hen the condenser C is charged t e potential on the grid of tube T will be raised sufiiciently to cause the tube to break down or discharge. Current will then flow over the following circuit: from battery B upper contact of relay A, from anode to cathode of tube T', through resistance R,, winding of relay B to ground. This will operate relay B. When relay A releases the above traced operating circuit for relay B will be broken at the lpper contact of relay A. The condenser will be discharged through resistance R While the invention has been disclosed as embodied in certain s cific forms which are deemed desirable, it is understood that it is capable of embodiment in many and other widely varied forms without departing from the spirit of the invention as defined by the appended claims.

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What is claimed is: y

1. A relay, a condenser, a charging circuit for said condenser controlled by said relay, two resistances in said charging circuit for limiting the potential applied thereto, a discharge circuit for said condenser, a gas filled tube in said discharge circuit adapted to be broken down after said condenser is charged, a second relay in said discharge circuit operated by the discharge of said condenser, means controlled by said second rela for short-circuiting the tube in said discharge circuit, and means controlled by said second relay for short circuiting one

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