High and Low Voltage Cut-Off with Delay and Alarm

Simple and easy build High and Low Voltage Cut-Off with Delay and Alarm Circuit. This straight forward circuit will protect electrical appli...

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Infrared Proximity Detector Alarm

This circuit can be built from readily available low-cost components, some of which may even be hiding in your junkbox! The indicated value ...

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Latch-Up Alarm Using Opto-Coupler

The latch-up alarm described here is based on single IC NE555, configured as an astable multivibrator. The timing components are selected su...

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Build a Very Simple Alarm System

The circuit presented here is a very simple and yet highly effective alarm system for protecting an object. The circuit requires no special ...

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Simple Clever Rain-Alarm

Usually rain-alarms employ a single sensor. A serious draw-back of this type of sensor is that even if a single drop of water falls on the s...

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Pc Temperature Alarm

If your PC overheats, it could damage its expensive components. Here’s a circuit that warns you of your PC getting heated. Today’s computers...

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Laser Based Intruder Alarm

You can use this laser-based intruder alarm conveniently at the entrance of a hall or any other similar location to protect the same from un...

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Simple Motorbike Alarm

This simple to build alarm can be fitted in bikes to protect them from being stolen. The tiny circuit can be hidden anywhere, without any co...

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Simple Current Monitor and Alarm

These circuits are intended for remote monitoring of the current consumption on the domestic mains line. The circuit in Fig. I lights the s...

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Fire Alarm Using Thermistor

Small and simple unit, Can be used for Home-Security purpose . In this fire alarm circuit, a Thermistor works as the heat sensor. When tempe...

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Car Alarm Sound Booster

For car alarms, emphasis should be put on hearing the audible alert and identifying it as belonging to your ‘wheels’. Unfortunately, modern ...

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Best Automatic Car Alarm

Even the best car alarm is useless if you forget to set it upon leaving your car, whence this circuit. The relay has a make and a break cont...

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Power Supply Failure Alarm

Most of the power supply failure indicator circuits need a separate power-supply for them-selves. But the alarm circuit presented here needs...

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Car Anti-Theft Wireless Alarm

This FM radio-controlled anti-theft alarm can be used with any vehicle having 6- to 12-volt DC supply system. The mini VHF, FM transmitter i...

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Simple Door Alarm

This circuit emits a beep and/or illuminates a LED when someone touches the door-handle from the outside. The alarm will sound until the cir...

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Cheap Bicycle Alarm Schematics

The author wanted a very cheap and simple alarm for some of his possessions, such as his electrically assisted bicycle. This alarm is based ...

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Pyro Electric Fire Alarm

Here is an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo element to detect fire. The lead...

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Broken Charger Connection Alarm

Detects if a device is not properly connected to its supply Suitable for battery chargers, portable appliance supplies etc. The above circui...

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Simple Gated Alarm

Sometimes the need arises for a simple, gated, pulsed alarm. The circuit shown here employs just four components and a piezo sounder and is ...

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Low-Cost Power Buzzer

How often on average do you have to call members of your family each day to tell them that dinner is ready, it’s time to leave, and the like...

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