Excess temperature alarm circuit diagram

Published:2011/9/15 22:32:00 Author:Rebekka | Keyword: Excess temperature alarm | From:SeekIC

This circuitis composed ofa CMOS gate CC4011. It uses the ordinary thermistor for temperature measurement and it can emit sound, light and alarm. The two doors around the left side form the 2HZ controllable oscillator, and thetwo doors on the right formthe 400HZ controlled oscillator. When the temperature is normal, the partial-pressureof thermistor resistor RT and resistor R is lower than threshold voltage of NAND gate, two oscillators do not work. Once it is over temperature, RT is small enough, the first class NAND gate opens, the oscillator works, and the red and green light-emitting diodes alternating work, thenlthe oudspeaker emitssound. To save the transistor,it requires two tubes with the β> 150.



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