The invention relates to an electronically controlled switch circuit and more particularly a switch electronically controlled to produce a noise-free single pulse output of a particular predetermined polarity irrespective of switch input noise resulting from switch contact bounce or line noise. 
Noise-free single pulse outputs of indefinite duration and a particular predetermined polarity are often required for testing electronic digital computer devices such as high speed memories and shift registers.  Noise-free single pulse outputs of a particular predetermined polarity may also be employed as power on pulses to establish logic circuits in a known state.