Fire alarm using thermistor & NE555

jacky March 8, 2012 53 Comments
Description. Many fire alarm circuits are presented here,but this time a new circuit using a thermistor and a timer to do the trick. The circuit is as simple and straight forward so that, it can be easily implemented. The...
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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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Variable frequency oscillator

jacky March 8, 2012 1 Comment
Description. Here is a simple variable frequency circuit based on timer NE555. Here NE55 is wired as an astable multivibrator, whose output frequency can be varied by varying a potentiometer. This circuit is a must in the work bench...
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Scoring game circuit

jacky January 24, 2012 13 Comments
Description. A simple scoring game circuit that can be used for all occasions when a dice is needed.The circuit is based on a NE555 timer,a 74LS192 counter,a74LS247 decoder and a & segment LED display.The timer IC1 will produce the...
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Light to Frequency converter circuit

jacky February 28, 2011 1 Comment
A simple Light to Frequency Converter Introduction. Here is the circuit diagram of a effective light to frequency converter circuit that can be used for variety of applications such as light intensity measurement,fun etc. The circuit is based on...
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Dual Tone Train Horn Circuit

jacky November 10, 2018 3 Comments
Dual Tone Train Horn Circuit – Description A dual tone train horn simulator circuit can be made using two NE 555 timers connected in cascade. Here instead of using two NE 555 timers a single NE 556 timer is...
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InfraRed (IR) Sensor/Detector Circuit

jacky November 6, 2018 11 Comments
InfraRed (IR) Sensor/Detector Circuit Description The IR circuit described below is mainly designed for liquid level detection or proximity detection. The IR sensors used here are an IR LED and an IR photo diode. The circuit operates by detecting the...
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Fridge Door Open Alarm

jacky November 3, 2018 11 Comments
Fridge Door Open Alarm Circuit Description A fridge door open alarm circuit is explained with its detailed working and circuit. The objective of this circuit is to produce an audible alarm when fridge is left open for more than...
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