Found in a 1964 CQ magazine this circuit consists of an automatic telegraphic key, providing the correct duration for points and dashes. The circuit can be made with a current PNP transistor.
This circuit was found in Motorola documentation from 1966. The lamps are according to power and...
This circuit, which uses components still common today, was found in a 1997 documentation. It...
This circuit is intended to apply the music signal from a stereo to a telephone line for the...