High Temperature Indicator Circuits

Published:2013/11/13 19:16:00 Author:lynne | Keyword: High Temperature Indicator | From:SeekIC

In some areas there is a need of temperature detectors which help them to detect temperature and indicate themwhether the temperature is low or not. The components needed for the circuit are: 3 Resistors 1 Temperature dependent resistor 5v battery Two 1n4007 diodes One Op-Amp One LED And the circuit working is actually very simple, the Op-amp is connected as Non-inverting comparator. And a bridge circuit is made with the resistors and a Temperature Dependent Resistor. From above circuit R1, R2 and R3 are normal resistors but RT is Temperature Dependent Resistor. The bridge resistance and RT are selected in such a way that as long as temperature is less than threshold value, the bridge is unbalanced by making Voltage at B more than voltage at A . Hence Vo = -Vsat and LED is reverse biased and remains OFF. When temperature becomes more than threshold then Voltage at B becomes less that Voltage at A hence it drives Vo = +Vsat. Due to this, LED glows and gives high temperature indication. If you have any doubts about the above circuit, don’t hesitate to comment.



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