This two-transistor circuit was found in a 1966 US documentation. The power transistors are of the time. The system is intended for cars with contact breaker.
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...