This circuit was obtained from Popular Electronics of the 1990s. The circuit uses common transistors today and the frequency is given by the crystal.
Closing and opening S1 for a moment to charge the capacitor, the transistor conducts the load. The...
The basic component of this circuit is a general-purpose SCR. The voltage is according to the...
This simple preamplifier was published in Radio Electronics magazine in February 1958. The battery...