We found this circuit in a 1976 publication. The transistors can be BC547 or 2N2222. Crystals up to a few tens of Megahertz can be tested. The LED can be of any type. The capacitors must all be ceramic.
This converter or inverter uses components that are still common. The transformer is the type...
The integrated circuits used in this oscillator are not very common today, as we obtained it in...
The circuit shown in the figure is sensitive to light. Its frequency is determined by the light...