This 4-transistor timer was found in the April 1975 issue of Radio Electronics magazine. It uses both single-ended and single-junction transistors to provide a dual audio output.
This circuit was found in a 1967 Raytheon manual. The transistors are from the time. Equivalent modern...
This circuit was published in a 1979 magazine, but it can still be easily assembled as the...
The circuit presented generates short pulses. This configuration was found in a publication from...