This circuit is from a 1969 EEE magazine. The transistors are from that time, but the circuit can be implemented with modern equivalents, such as 2N2646 for Q3.
Found with variations on this site, this circuit was taken from an American documentation from the...
This circuit generates damped sounds imitating a drum or other percussion instrument with...
This is the traditional configuration for a limit comparator or window comparator, using two...