This variable frequency circuit was found in a Popular Electronics from the 90s. The circuit outputs to a small speaker and can be powered by voltages as low as 3 V.
Found in Linear Technology documentation from the 1980s, this circuit has an accuracy of 0.01%....
This amplifier circuit for listening was found in a book by Hugo Gernsback from 1960. The...
This circuit is from a current regulator up to 1 A, ie a constant current source. The LM320...