This is a battery powered 3W power amplifier using germanium transistors. The circuit is from an English documentation from 1967. The transistors are from the time.
This circuit was obtained in a 1974 Motorola timers publication. Transistors allow equivalents, the 2N2646...
This is one of the many anti-deboucer circuits the reader can find on this site. The base is TTL...
This circuit, found in a 1994 documentation, uses 20 A 2N5448 triacs or equivalent and should be...