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.
This circuit makes the RIAA equalization of signals obtained from a record player for recovery in other...
This is a diagram of a 1958 commercial receiver. The circuit was found in documentation at the...
This circuit uses an 18 MHz crystal to generate 36 MHz signals. We found it in an 80's...