Suggested by Mullard in an old documentation, this circuit is based on a common phototransistor and on transistors that may be the modern BC548.
The duration of the output pulse in this circuit depends on C. This capacitor can have values in...
This circuit is from the time when cars used contact breakers. This 80's version measures the dwell...
We found this touch switch in a 1992 Electronics Handbook. The circuit can be assembled with 6 or...