GB866375A - Transistor apparatus for producing trains of short current pulses - Google Patents

Abstract

866,375. Transistor pulse generating circuits. SNEATH, O. B. Oct. 28, 1959 [Oct. 29, 1958], No. 34571/58. Class 40(6) [Also in Groups VI and XL(b)] Trains of pulses are produced by interrupting, be means of a transistor, longer pulses which are applied to a transformer, the transformer having a step up ratio to a potentiometer for regulating the output voltage. The Figure shows a squegging oscillator of the type described in Specification 864,959 comprising a transistor T1, tuned transformer L1, C3, and a time constant circuit including potentiometer R2 and capacitors Cl, C2, the arrangement being such that variation of the setting of the potentiometer gives a wide range in the repetition frequency of the sawtooth shaped pulses produced by the circuit. These pulses are applied through an emitter follower transistor T2 to a transistor T3 so that each pulse progressively charges capacitor C5. The voltage across this capacitor forms the collector supply source for a blocking oscillator transistor T4 which, when the voltage across the capacitor C5 rises to a sufficiently high value, commences to oscillate producing high voltage output pulses across the output terminals of a potentiometer R7. The pulses increase in amplitude until the termination of the pulse across capacitor C5 when oscillation ceases while the capacitor voltage rises again to a sufficient level to allow oscillation to restart. A switch S2 enables the pulse repetition frequency to be decreased, a switch S1 enables the input to be removed from transistor T2 so that continuous oscillation of transistor T4 takes place, and a switch S3 permits the squegging oscillator circuit to be damped so that continuous oscillation takes place and the operation of the blocking oscillator transistor T4 is interrupted. Terminals MN are provided for an alternative source of supply for the circuit or for recharging the internal source.