This circuit was found in old American documentation. Transistor is general purpose and coil rated is for 1.5 MHz. Wind 50 + 50 turns of wire 28 onto ferrite rod for 1 MHz.
This power supply, found in an Argentine publication from the 1970s, uses a wire potentiometer of 25 W or more...
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...
The oscillator shown in the figure generates a 1 kHz tone that is reproduced on the speaker with...