Found in a PE Hobbyst Handbook of 1991, this circuit was originally proposed to time photographic baths in developing rooms but can be used for other purposes. The circuit beeps at 30-second intervals.
This two-transistor constant current source is from a 1968 documentation. Modern equivalent...
This circuit is intended to increase the width of a pulse. The circuit is TTL and can be used as a...
This circuit was found in a 1977 documentation. The gain is 3 dB and instead of the original...