This circuit provides a signal when dialing occurs. The circuit is powered by the telephone line voltage itself. We found it in an old documentation.
This pulse amplifier with optical isolator is from a Motorola manual from 1973. The transistors can be...
This circuit is from an 80's documentation. The BC108 can be replaced by the BC548 and the 2N3055...
This circuit is designed to obtain a negative voltage from a positive supply for circuit...