We found this circuit in an American documentation from the 1990s. The circuit is based on the LM3909, a low power oscillator from National Semiconductor.
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...