High & Low voltage cut-off with delay& alarm

jacky March 8, 2012 101 Comments
Description. This straight forward circuit will protect electrical appliances from over voltage as well as under voltage. The circuit also produces an alarm when the power supply comes back. An ideal circuit for home to protect your valuable equipments...
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Mosquito repeller power saver

admin February 16, 2012 7 Comments
Description. Almost all liquidator type mosquito repellers are rated 5Watts. It is a pretty energy consuming game  when these repellers are operated through out the night. Even though these liquidators are switched ON and OFF in discrete intervals there...
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Cat repeller circuit

admin February 15, 2012 5 Comments
With this cool cat/dog repeller circuit you could chase the cats  off  from any where you want. In fact, I designed this circuit to chase my cat from my computer table. Most of the animals like cats respond violently...
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Infrared Motion Detector Circuit

admin August 3, 2016 255 Comments
In this tutorial, we have explained how to build a DIY (Do It Yourself) Infrared Motion Detector Circuit using 555 Timer IC, IR Diode, 2 comparator IC’s and other associated components. An Infrared Motion Detector circuit can be designed...
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Low cost fire alarm circuit.

admin January 21, 2014 89 Comments
Description. When there is a fire breakout in the room the temperature increases. This ultra compact and low cost fire alarm senses fire breakout based on this fact. Transistor BC177 (Q1) is used as the fire sensor here. When...
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Rain alarm circuit

admin January 21, 2014 64 Comments
Description. Here is a simple rain alarm circuit that produces an audible alarm when ever rain falls. The rain detector circuit is based on two transistors (Q1 & Q2) and a NE555IC (IC1). The two transistors are wired as...
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Transformerless power supply circuit

jacky February 24, 2011 17 Comments
Transformerless power supply Description. Here is a low cost and simple circuit that can be used to power up small electronics devices. The power is directly tapped from the mains via resistor R1.D1 rectifies the voltage and C1 and...
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USB LED Lamp circuit.

admin February 23, 2011 19 Comments
USB Lamp Circuit Description. Here is a simple USB powered lamp that can be used to light your desktop during power failures. The circuit operates from the 5 Volt available from the USB port.The 5V from the USB port...
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Remote controlled switch circuit

admin November 15, 2011 49 Comments
Remote controlled switch for Appliance Description. Here is a versatile remote controlled  switch that can ON or OFF any appliance connected to it using a TV remote. IR remote sensor IC TSOP 1738 is used for receiving the signal....
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Simple Alarm circuit

admin February 23, 2011 1 Comment
Multi Tone Alarm Description This is a simple and easy to build multi tone alarm circuit that can be used in burglar alarms or sirens. The circuit is based on dual op amp MC1458 and  LM 380. The two...
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