Found in Popular Electronics from the 90s, this circuit generates signals in a frequency range set to R7 and basically determined by C1. Operational and equivalent transistors can be used.
This circuit is from a specialized documentation in 1992 FETs. The L1 coil has 0.07 uH with...
The LM1468L can also be used. The circuit is from Motorola's Linear Interface ICs and the...
This low frequency doubler requires a 50 mV signal at the input. The circuit is from an old...