GB888894A - Improvements in or relating to pulse amplitude discriminating circuits - Google Patents

Abstract

888,894. Transistor pulse discriminating circuits. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. May 12, 1960 [May 26, 1959], No. 17884/59. Class 40(6). The threshold level of a pulse amplitude discriminator is controlled by feeding pulses of standard amplitude into the input, the resulting output being gated, rectified and used to provide a bias voltage to the discriminator so that it just passes pulses of standard amplitude. As shown, an avalanche transistor J3 is triggered by any pulses arriving at terminal 8 having an amplitude above a predetermined threshold value. The negative output pulses from J3 are passed via an emitter follower J4 to the output terminal 9. Standard amplitude pulses at 50 c/s. are provided by transistor J7. The output from these pulses is selected by the gating transistor J5 (rendered conductive by 50 c/s. pulses from TR2), rectified by a diode pump circuit comprising components D2, D3, C2, C3 and the resulting direct current, passed by the emitter follower J6 to control the threshold level of J3 so that standard amplitude pulses are just sufficient to trigger the discriminator. The standard pulses are eliminated from terminal 9 by means not shown. In Fig. 1 (not shown) the controlling bias is derived by rectifying the output of a blocking oscillator fed from the gating circuit and is used to control the gain of the first stage of a transistor amplifier preceding the discriminating trigger circuit.