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Vehicle Anti-Hijack Alarm No. 3 - Like the first two Hijack Alarms - if a door is opened while the ignition is switched on - the circuit will trip. And after a few minutes delay - when the thief is at a safe distance - the Siren will sound. But this time the engine does not go on to fail automatically. Instead - it will continue to run until the thief turns off the ignition. Then the engine will not re-start.

Vehicle Anti-Theft Alarm - This car alarm circuit features Exit and Entry delays, an instant alarm zone, an intermittent siren output and automatic Reset. By adding external relays you can immobilize the vehicle and flash the lights.  (circuit design added 05/08)

Wailing Alarm - (schematic / circuit added 10/02)

Warble Alarm(Tony van Roon's circuits added 08/09)

Water Activated Alarm - The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. However as the probes get wet the transistor will conduct and sounding the alarm. An On/Off switch is provided and remember to use a non-reactive metal....(diagram added 6/03)

Water Level Alarm (Andy Collison) - A circuit that offers visual indication of fluid level in a vessel, with a switchable audible alarm. Example uses would be to monitor the level of water in a bath or cold storage tank...(schematic added 9/02)

Water Level Indicator with alarm - This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full.  The circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs. When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch....  (added 10/05)

Water Seepage Alarm - This simple circuit sounds a beeper when its electrodes detect water. It is powered by a single 1.5v N cell. A small 1.5v button battery will also work. ….(designed by David A. Johnson)

Water-level Alert - Beeper or flashing LED alert.  (electronic design added 6/07)

Whooper Alarm, #1If you've ever watched any TV at all and seen those old WWII navy movies, you've heard that distinctive "whoop-whoop-whoop" as a destroyer sliced through the waves, guns blazing, and everybody yelling "battle stations!"....(Tony van Roon's circuits added 08/09)

Whooper Alarm, #2Destroyer Whooper alarm using 5 transistors  (Tony van Roon's circuits added 08/09)

Wire Loop Alarm (Aaron Cake) - (circuit added 08/08/08)

Wireless Alarm - Making yourself an alarm is both useful and interesting: but the best part is when you take the remote control out of your pocket, and switch on the alarm while saying to your friends: "I've done it in a weekend". Making yourself an alarm gives you maximum flexibility: as this project works according to the Nutchip truth table, you can change it to suit your needs. Some people would like to have like a "panic" button, in order to sound the siren. Some other pepople need a very long time to leave the house. Or you might be looking for an alarm that keeps that special sensor on even if you are at home. Possibilites are unlimited!....(added 05/06)

Zone Alarm - This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It has provision for normally-open and normally-closed switches and will accommodate the usual input devices...(circuit design added 08/08/08)