pulse/pulse train generator

elektor july/august 1983 52 pulse/pulse train generator This circuit has two modes of oper- ation. If the pushbutton is just pressed once a single noise-free pulse appears at the output; the pulse can be positive or negative depending on whether the positive or negative output is chosen. If the pushbutton is pressed and held then, after a short delay, a pulse train is produced which continues until the button is released. This dual-function oper- ation makes this a very handy circuit which can be used, for example, where a counter must be driven either step-by-step or at a fixed frequency. The whole circuit consists of an anti-noise network (R2/C1), a pulse shaper (N1), an oscillator (N2) and two Schmitt triggers (N3 and N4) which enable It to produce both positive and negative pulses. When Si is pressed once R2/C1 eliminate any interference which might be present (switching noise for example), and then Schmitt trigger Nl delivers a clean pulse which is further cleaned up by N3 (a...