This circuit was described in an article in the February 1993 Radio Electronics magazine. The frequency depends on the crystal and L1 is optional.
This circuit is from an old American documentation. The circuit generates 20 to 200 ms steps for...
This circuit, found in American documentation, works as a voltage doubler, enabling the supply of a...
This circuit was taken from a Popular Electronics from January 1967. Transistors are from the...