The temperature measuring circuit

Published:2011/6/6 21:51:00 Author:qqtang | Keyword: temperature measuring | From:SeekIC

In the figure is the temperature measuring circuit, and S1 is the point/bar display mode shifting switch. When the voltage of the power supply is Vcc>8V, LED1～LED10 don't need to connect the current limiting resistor in the serial way. When LED is glowing, the current is set by the external resistors of 4-pin and 6-pin, if 4-pin and 6-pin connect a resistor of 1.2kΩ(including the resistors btween R1, BP1 central head and 4-pin), which connects with transformer of 10kΩ in LM3914 in the parallel way, and then the resistance between 4-pin and 6-pin is about 10.7kΩ, the basic voltage of 1.25v provides the transformer circuit with a current of 1.25V／1.07kΩ≈1.2mA.



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