Burglar Alarm with Time Delay NE555 DIY soldering kit.
The assembled module requires 5V power supply (standard 2.1/5.5mm DC plug). We recommend our 5V USB power supply cable.
The system is armed when jumper J1 is closed, and J2 is open. Replace J1 with a normally-closed door or window contact, or a trap wire. As soon the contact opens, the delay of some seconds starts. Time enough to flip a secret switch to turn the system off. If not turned off, the alarm will start to sound and the 2 LEDs will flash.
J2 can be connected to a panic or test switch. As soon J2 is closed, the alarm sounds, independent of the state of jumper J1.
