This Public Address amplifier was found in an American publication from 1947. The circuit uses 5 tubes and a transformer source.
This circuit can use any comparator or even an operational amplifier. We can use the LM339 and the...
This circuit is from an 80's American documentation. The circuit uses components of the time which...
The pulse duration is determined by the 100k resistor and the separation by the 1M resistor. The...