This power supply is based on the 723 integrated circuit, which is no longer very common today. The transistor must have a heatsink and the bridge can be formed by diodes 1N4002 or equivalent.
This alarm uses several sensors that directly trigger a sensitive relay. A larger relay can be...
This circuit for counting down pulses was found in the September 1983 issue of Radio Electronics...
Indicated by Popular Electronics to be used with a car headlight, this circuit can also have...