GB587106A - Thermionic pulse generator - Google Patents

Abstract

587,106. Pulse generators. HAZELTINE CORPORATION. Jan. 4, 1945, No. 429. Convention date, Feb. 9, 1944. [Class 40 (v)] A pulse generator produces a pulse with an undesirable exponential portion which is eliminated by combining it differentially with a second pulse which has a steep edge and an exponential portion coincident with the undesirable portion of the first pulse. Fig. 1 shows an auxiliary generator 19 applying triggering pulses A, C (Fig. 2), through transformer 20 to the grids of gas tubes 10, 101 respectively which are normally quiescent. The positive peak in wave form A causes tube 10 to conduct and capacitor 11 discharges exponentially through the gas tube (curve B) until the positive peak in wave form C causes tube 10<1> to conduct and begin to discharge capacitor 11 as represented by curve D. Mutual inductance between coils 12, 12<1> reduces their effective impedance, increasing the value of discharge current from capacitor 11 at instant t1 and also the subsequent rate of discharge. The circuit constants are adjusted to give identical exponential discharge wave-forms in each half of the circuit when both gas tubes are conducting, and as the discharge currents flow in opposite directions through coils 12, 12<1> they produce no resultant effect in the common output coil 16. Accordingly the voltage output at terminals 17, 18 is substantially rectangular as shown in curve F. At time t2 capacitors 11, 11<1> have discharged sufficiently to extinguish tubes 10, 10<1> and thereafter the capacitors recharge slowly to their initial condition before the incidence of the next triggering pulse from source 19. In Fig. 3, not shown, generator 19<1> produces rectangular pulses which determine the output pulse width, and transformer 20 is replaced by a differentiating network for producing the triggering wave forms A and C. Fig. 4 shows a modification in which generator 191 applies the triggering pulse to tube 10 directly and to tube 10<1> through a delay network which determines the width of the output pulse.