This circuit is from 1967 General Electric documentation. It uses SUS which are not very common components today. The maximum frequency should not exceed a few kilohertz.
This circuit was taken from the 1974 Ferranti transistor manual. Note the shapes of the signals....
This mini siren, found in a 2003 publication, powers a small piezoelectric transducer, but a...
This fuzz effect is from a 1988 Italian publication, but it can be easily assembled, as the...