With this circuit found in an American documentation from 1969 it is possible to vary the selectivity (Q factor) of a tuned circuit. The operational is from that time.
This 10-transistor radio was found in Radio Electronics magazine from December 1964. The...
This oscillator uses one of the four ports of a 74C14 integrated circuit and can generate 100 kHz...
This simple humidity alarm circuit includes a timed warning oscillator whose time is set to R4....