Thermostat schematic of thermistor electric water heater

Published:2012/8/16 22:27:00 Author:Ecco | Keyword: Thermostat schematic , thermistor, electric water heater | From:SeekIC

The circuit consistes of thermistor RT, comparator, driverand heater RL. The circuit can keep water temperature at 90 ℃ by automatically opening and closing control of the heater. When temperature is at 25 ℃ thermistor resistance is 1OOkΩ, temperature coefficient of 1K / ℃. When comparator's inverting input end is added the 3.9V reference voltage, the comparator's noninverting input terminal is added the partial pressure voltage of RP and thermistor RT. When the water temperature belows 90 ℃, the comparator IC outputs high potential to drive VT1 and VT2 conduction, then the relay K works, heater circuit is closed; when the temperature is higher than 90 ℃, comparator IC output is in low potential, VT1 and VT2 are cut-off, the heater circuit is disconnected by relay K. Adjusting RP obtain the required water temperature.



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