Based on NXP 74HC logic, this circuit can be adapted for various uses. The circuit can also be used with 12V power, and the circuit replaced with a common 4046 PLL.
This circuit was found in old American documentation. Transistor is general purpose and relay is...
This simple alarm with latching uses a relay as the main element. The circuit is from a Radio...
This circuit is from an Italian publication called Fare Elettronica from 1987. What we have is an...