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Unorthodox warning alarm circuit presented here is infact a single chip based general purpose sounder, which produces a pulsed alert tone when its input receives a valid trigger signal. The circuit can be easily interfaced with a number of electronic gadgets and sensors and it requires only 12V dc supply input for proper working. A positive level input at trigger point (J1) activates the warning alarm unit.
We are in a digital era! Now we can add some intelligence to our doors and gates without too much investments. Just assemble this little door timer circuit built around a few cheap and simple components and link it to any door/gate as per your requirement and taste. If the door/gate remains in open condition for a prefixed time an acoustic sounder starts beeping to raise an alert. Enough?
Ultra simple circuit of the tilt sensor alarm presented here can be fabricated using readily available inexpensive components. The circuit is a true transistor based design. Home made Tilt sensor for this circuit is an ordinary little glass/plastic bottle with two metal needles inserted through its cap, and a small quantity of water inside.
You can also try your own ideas to make the tilt sensor. A 9V alkaline battery is enough for powering the whole circuit.
The locker alarm circuit or cashbox watcher can be used to protect a cashbox/locker from unauthorised access. This tried and tested design forms a fool-proof,remotely operated alarm/electromagnetic relay driver that receives its control signal from a standard reed switch. The circuit works off a 12V dc power supply.
