Any sensor or piezo capsule can be used as a sensor in this circuit. The integrated circuit is also common in our days and a table of sensor voltage levels.
This circuit came out in an English publication from 1973, but it can be easily assembled using a...
This circuit uses components of the time. We found it in a 1968 US documentation. The delay is 100 ns...
This circuit makes use of a special LM195 power transistor not very easy to obtain. The circuit is from...