This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The indicator is a common 1 mA full-scale milliammeter.
This fully isolated control circuit provides an output signal by triggering a 130 mA relay when...
The capacitor used in this circuit can have values between 5 and 30 uF. The circuit is of old...
We found this circuit in an old Argentine publication. The transistor can be replaced by a more...