This circuit was found in an old documentation for radio amateurs. The circuit makes use of an uncommon integrated today. The circuit converts telegraph signals to be used on the computer.
We found this circuit in a 1985 technical publication. The circuit uses PUTs to drive lamps....
This high-powered megaphone circuit is from a Radio Electronics from December 1964. Note the use...
This amplifier with differential input uses two old op amps but can be implemented with modern op amps....