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  • Here are 2 heat sensor circuits, first one is build with the 4060 IC, the second one is simpler than the one before and has fewer components. It is an ideal add on circuit to monitor heat in CD players, Amplifiers etc. It senses heat from electronic devices and gives a warning alarm.

    Heat Sensor Schematic with the 4060 IC

    heat sensor with 4060 IC

    Heat Sensor Schematic with the transistor

    heat sensor with transistor

    The heat sensing element is the NTC Thermister and its resistance drops when the temperature increases. Resistance of Thermister is set by VR and if the temperature is below the preset level, transistor T1 will be out of conduction and keeps the buzzer and LED off. When the temperature near the Thermister increases, T1 conducts and buzzer beeps.

    attentionThe author D Mohankumar is not an active member anymore. Please take into consideration that the presented information might not be correct.
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    6 Responses to "Heat Sensor Circuit"

    1. osama mohammed says: on December 10, 2010 at 3:58 am

      is the capacitor 0.22Farad?


    3. Sir good day.. Sir its functional if i will use a NTC 4.7k BIG in size and BLACK in color?In my place all enterprise only sell a big type thermistor that use for TV?

    4. This circuit DOES NOT WORK. Do not build it.

    5. I think

      1. The circuit may work but it will be very difficult to adjust the 10K pot to suit the change in resistance of the 4K7 NTC thermistor

      2. An active piezo-buzzer is connected directly to pin 5 of CD4060. Not a good practice!

    6. The CD 4060 is a DIGITAL CHIP. Pin 12 needs a DIGITAL SIGNAL to start and stop the chip. This involves a voltage from 0v to near rail voltage. How is a thermistor going to provide this voltage??????

      The chip will deliver 10mA. What piezo buzzer works on 10mA??????
      Just another circuit from D Mohankumar that does not work.

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