This circuit was found in 80's telecom documentation. Its purpose is to control a microphone in the process of transmitting voice and Morse signals.
This 1995 circuit uses interruption sensors or NC connected in series in any quantity. With the...
The integrated circuit used in this amplifier is not common today. The circuit is from a...
This circuit turns off a load after an interval of 8 to 80 seconds adjusted on the potentiometer. The...