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This variable frequency oscillator was found in an old American documentation. Transistors allow more modern equivalents and coil data are found next to the diagram for several frequency bands.
We found this circuit in a Popular Electronics of the 90s. The circuit still uses light bulbs, but...
Instead of LED bulbs, LEDs with a series 470 ohm 1k resistor can be used in this 80's circuit....
This simple circuit can use any general-purpose transistor. The power supply must be isolated. The circuit...