Патент USA US2411598код для вставки
Nov. 26, 1946. 2m @,598 J. _P. SMITH KEYING CIRCUI T Firled JAanQ 22, 1943 a n@M/ W. ¿wmw@00«œwfc WM Mw.if i. l/ . »a _áâN/ f . 6,6/0 VaL M65 aF» M552' îit Í ßnventot ACîttorneg Patented Nov. 26, 1946 *fi‘UNlrED STATES >PATENT orifice ' 2,411,598 KEYING cmcm'r' » John P. Smith, Cranbury, N. J., assigner to Radio Corporation of America, a corporation of Dela Ware Application January 22, 1943, Serial No. 473,259 s anims. (c1. 25o-27) 1 My invention relates to keying or switching cir cuitsV and particularly to an electrical circuit wherein electrical pulses are produced under the control of mechanical switching. . 2 Tube IS has a grid resistor RI and a grid ca-v pacitor Ci having comparatively large resist ance and/or capacity, respectively, whereby the time constant of the circuit RI-CI is com One object of the invention is to provide an 5 paratively large. Thetube ZI has a grid leak improved means for obtaining short electrical resistor R2 and a grid capacitor C2 having com Another object of the invention is to provide paratively small values so-that the time constant of circuit R2-C2 is comparatively small. The cathode end of resistor R2 may be connected to an improved means for obtaining electrical a variable tap 28 on a source of positive biasing pulses which occur synchronously with the rota voltage for controlling the width of the multi vibrator pulses. A bypass capacitor 29 may be provided. The cathode circuit of the tube I9 includes the pulses in response to the actuation of a me chanical switch. tion or other motion of a mechanical element. >-In a preferred embodiment of the invention, I utilize an asymmetrical multivibrator and con nect the mechanical switch in the cathode cir 15 switch i3 so that the cathode of tube I9 is con cuit of the multivibrator tube that has the longer grid capacitor-grid leak resistor time constant. A short electrical pulse is generated in response to closing the cathode circuit by the switch, the nected to ground through the conductors 3l and 32 and the switch I3 when the switch I3 is closed. When switch I3 is closed, plate current flows through tube i9 to cause a voltage pulse 35 of pulse ending before the switch is opened. Also, 20 short duration to appear on the plate of tube 2I. The action of the circuit in producing the the longer time constant is adjusted so that the grid capacitor of said tube is substantially fully desired short pulse is illustrated by the graph in Fig. 2 showing the voltage on the grid of tube discharged before the switch is again closed. 2l and by the diagram in Fig. 3 showing the dif 'I'he invention will be better understood from the following description taken in connection 25 ferent time relations. The action is substantially as follows: When the switch I3 closes there is with the accompanying drawing in which an increase of current flow through the tube I9 Figure 1 is a circuit diagram illustrating one which causes its plate to go more negative and embodiment of the invention, drive the grid of tube 2| more negative. This Figure 2 is a graph that is referred to in ex 30 decreases the plate current through tube ZI to plaining the operation of Fig. 1, make its plate more positive whereby the grid Figure 3 is a graph showing the time relations of tube I 9 is made more positive, thus further between the switch operation and the multi increasing the current flow in tube I9 and rein vibrator output, and ' ` forcing the negative charge on grid capacitor C2. Figure 4 is a graph illustrating another method 35 As a result, the tube ZI is almost instantly driven of practicing the invention. to plate current cutoff to produce the front edge In Fig. l, one embodiment of the invention is of the short pulse 3S. This cutoiî condition is shown applied to a system wherein a directional held until the charge of the capacitor C2 leaks antenna I0 is rotated about a vertical shaft or oif through resistor R2 enough to let the grid of axis I I at a constant speed. It is desired to pro duce a, short electrical pulse each time the an 40 tube 2! go positive. The plate of tube ZI now goes negative, whereby the capacitor CI is tenna I0 reaches a certain position, for example, charged to block the tube I9, thus producing the each time the antenna radiation pattern is point back edge of the said short pulse 36. Because of ing north. the comparatively long time constant of the cir A switch i3 located near the antenna Il) is closed periodically by a cam I4 'as the antenna is 45 cuit Ci--Ri, the tube I9 remains blocked for a comparatively long period and as a result the in rotated. The cam I4 may be mechanically cou terval between the successive short pulses is long pled to the shaft II as indicated by the broken compared to the width or duration of these pulses. line I6 sc that the switch I3 closes once for each The width of the pulses 3S may be controlled rotation of the antenna. A multivibrator I8, which may be located at a 50 by adjusting the tap 28 to change the positive bias on the grid of tube ZI, this bias adjustment point remote from the antenna Ill, comprises two having the same effect as changing the values three-element vacuum tubes I9 and 2|. Plate of the elements C2 and R2. In one specific em voltage is applied to the tubes through plate re bodiment of the invention the circuit time con sistors 22 and 23. The resistor 24 and capacitor 55 stants and the bias for tube 2| were so adjusted 26 are ñlter elements. 2,411,598 4 3 tube> to break the flow of plate current there that the short pulse was approximately 1/20 sec onds long while the time for complete discharge through when the switch is open, and means for of the capacitor CI was three and one-half sec periodically closing said switch for a length of time that exceeds the duration of the shorter ends, this being the condition illustrated in Figs. 2 and 3. As indicated in Fig. 3, the capacitor CI issub duration voltage pulses produced at the plate of said other tube. 2. In combination, an asymmetrical multivi stantially completely discharged between the brator comprising a pairof tubes each having a time the antenna switch I3 opens and the time it is again closed. In the example illustrated the cathode circuit, an anode vand a control grid and switch I3 has an “on” time of one second and a 10 further comprising a -grid capacitor and a grid leak resistor connected to the control grids of said tubes, respectively, one of Said tubes having recurrent closing rate of six seconds. If desired, the invention may be utilized to pro vide more than one short pulsefor each actua-` tion of the mechanical switch. In this case the a grid capacitor and a grid leak resistor that have a substantially longer time constant »than thel grid capacitor and grid leak resistor of the other tube, a switch connected in the cathode circuit of said one tube, and means for periodically closing said switch for a length of time that exceeds the duration of the shorter duration voltage pulses 20 produced at the plate of >said other tube. Widths of the short pulses would be determined by the time constant of the circuit C2-R2 and the intervals between pulses would be determined by the time constant of the circuit C I-RI . Thus, if instead of the arrangement illustrated in Fig. 3, the switch I3 remains closed for seven seconds, as indicated in Fig. 4, three short pulses would be Ygenerated with an accuracy of timing depending on the multivibrator constants. By reducing the time constant of the circuit RI-CI the natural vperiod of the multivibrator may be decreased so 25 `that for seven seconds “on” time for switch I3 more than two short pulses may be generated. 3. In combination, an asymmetrical multivi brator comprising a pair of tubes each having a cathode circuit, an anode and a control grid and further comprising a grid capacitor and a grid leak resistor connected to the control grids of said tubes, respectively, one of said tubes having a grid capacitor and a grid leak resistor that have a substantially longer time constant than the grid capacitor and grid leak resistor of the other 1. In combination, an asymmetrical multivi brator comprising a pair of tubes each having a 30 tube, a switch connected in the cathode circuit of said one tube, and means for periodically clos cathode circuit, an anode and a control grid and further comprising a grid capacitor and a grid ing said switch for a »length of time that exceeds the duration of the shorter duration voltage leak resistor connected to the control grids of saidpulses produced at the plate of said other tube tubes, respectively, one of said tubes having a grid capacitor and a grid leak resistor that have but which is less than the natural period of the a substantially longer time constant than the multivibrator. grid capacitor and grid leak resistor of the other JOI-IN P. SMITH. tube, a switch connected in the circuit of said one I claim as my invention: y '