Abstract: A pulse timer circuit comprising a monostable multivibrator which includes two complementary transistors Q5, Q6, has the advantage of good tolerance to temperature fluctuation owing to the provision of a Schottky diode D4 connected between the emitter and base of one of the transistors Q5. The Schottky diode, D4, which has a temperature coefficient matched to that of the transistor Q5, ensures that the output pulse width from the monostable is unaffected by fluctuations in ambient temperature.

Abstract: A threshold detector circuit (2) suitable for use with a nuclear event detector for sensing an ionising radiation pulse has a high tolerance to ambient temperature fluctuations. The threshold detector (2) comprises an amplifier stage (3) which includes a pair of complementary transistors (Q2, Q3) and a comparator stage (6) which includes a third transistor (Q4) and a voltage reference (7). Temperature compensation is achieved by the addition of a feedback loop (5) in the amplifier stage (3) including a fourth transistor (Q1) whose temperature coefficient is closely matched to that of the third transistor (Q4).