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Road Ice Alarm electronic schematic circuit |
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This road ice alarm electronic circuit schematic use a LM3900 quad operational amplifier . As a temperature sensor this road ice alarm circuit use a thermistor . When the temperature is around 36 degrees Fahrenheit (2.2 celsius degrees ) the LED connected on pin 4 at the LM3900 op amp will flashes at once about each one second . When the temperature is going down to 32 degrees Fahrenheit (0 degrees Celsius ) the led remains on . Before you use this road ice alarm electronic circuit you need to calibrate it . To calibrate the circuit you need to put the thermistor in a mixture of a crushed ice and water and adjust the variable resistor R2 until the LED is remaining on . The road ice alarm circuit needs to be powered from a 12 volts DC power supply circuit ( If you use it for car the car battery can be used for powering the circuit ) .

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