The circuit is from a Radio Electronics magazine from October 1987. The Triac must be equipped with a heatsink and the transistors are general purpose.
In the original publication of the 90s a 556 consisting of a double 555 is suggested. The circuit...
This circuit was found in a 1966 EEE. The circuit uses transistors from the time but can be made...
This circuit can be used in alarms by activating a relay or a current load that depends on the...