The detector glaciation , by controlling the temperature of the ambient air, warns the driver of the occurrence of conditions for the formation of ice on the road in wet weather at temperatures from 0° to 2.2°C.
The scheme controls the duration of the flash of the led HL1: at a temperature of 2.2° the flash is short, when the temperature decreases to zero flash becomes longer, following once per second. As the temperature sensor is used the thermistor's nominal resistance at 25°C is 15 ohms.
The thermistor is mounted in the enclosure and is in contact with the surrounding air. A2 operates as a self-oscillating multivibrator with a period of 1 Hz, with the capacitor C1 is removed sawtooth pulses.
The chip is the comparator A3, the lower the temperature, the more the pulse duration at the output of A3, the longer the flash of the led.
Domestic analogue circuits LM3900 is UD.