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 circuit found in a 1993 Electronics Hobbyst Handbook has a very simple configuration that can be used on...
This sound effect circuit is from a Radio Electronics magazine from December 1969. The transistors...
This non-pulse alarm can be used as an event detector or even an alarm. The circuit can also be...