This circuit is from an American 1967 documentation and can be implemented with modern equivalent transistors. The circuit serves as a Q multiplier.
If you have an old cassette player or bought one from a junk shop, you can set up a small table...
This Linear Technology circuit was found in a 1980s documentation. The circuit can swing up to a...
This metal detector circuit uses an AM radio as an indicator. The radio is placed off-station and tuned...