This circuit was found in a 1970 US publication. Transistors are still common and the circuit can be used as a PWM shield or pulse transmission modulator.
The drive levels of this shield are opposite to the previous one. The photo-transistor can be of...
This circuit was found in a Radio Electronics of July 1984. It consists of the traditional 1 A...
This flasher or neon signal powered by batteries was found in old documentation. The transformer must...