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.
I found this circuit in a 1978 publication. The circuit can be assembled with a BD136 transistor to...
This basic TTL watch and minute clock circuit was found in European documentation from the 1970s....
This simple windscreen wiper interval was found in old American documentation. The relay must have...