This circuit with a differential pair was found in the August 1974 Radio Electronics magazine. The frequency is determined by L1 and the variable capacitor.
Using the LM380, this circuit provides a power of the order of 200 mW. In it we have a stage of...
I found this circuit in an article in a 2003 publication. The circuit is an example of how to...
We found this circuit in a Radio Electronics from October 1965. The pickup coil can be of the...