GB844404A - Improvements relating to electrical pulse generating apparatus - Google Patents

Abstract

844,404. Pulse-generating circuits. METROPOLITAN-VICKERS ELECTRICAL CO. Ltd. July 24, 1958 [July 19, 1957], No. 22965/57. Class 40(6). A pulse generator comprises a pulse forming network charged via a rectifier from an alternating voltage source in series with a direct voltage source of the order of the peak value of the alternating voltage and means for discharging the PFN into a load when the alternating voltage is in the neighbourhood of its maximum value opposing the direct voltage. As shown, an A.C. source is fed via a transformer T in series with a D.C. source via a grid controlled rectifier R to charge a pulse forming network PFN. The direct voltage is equal to the peak value of the alternating voltage or, as shown in Fig. 3, the alternating voltage may be somewhat greater. The rectifier R holds the charge on the PFN when a positive peak is reached as shown at H. The PFN is discharged through the load L by triggering a thyratron or ignitron, represented by S at time t. Continuous ionisation or "firing through" of the switching tube S is prevented by arranging that triggering time t occurs when the voltage across the rectifier R is zero or, as shown, reversed. The triggering is derived from the A.C. supply via a control circuit C. The PFN may alternatively be discharged at a submultiple of the supply frequency. As an added precaution a gating circuit D is provided to prevent the rectifier R conducting when the switching tube S is being triggered. In Fig. 1, (not shown), the gate D is omitted and a two-electrode rectifier is employed. Negative charging may alternatively be used. The A.C. and D.C. supplies may have separate or common voltage stabilization. The D.C. may be obtained from a stabilized A.C. supply or from one or more rotary or other generators in series having excitations provided by grid controlled rectifiers or transductors.