Electronic body temperature meter circuit ----- Electronic THERMOMETER

Electronic body temperature meter circuit The electronic thermometer circuit is shown in the figure. It consists of a medium gain operation amplifier Fc3, a negative temperature coefficient of thermistor RT, VD1 to VD4 diode bridge rectification and VT1, VT2 switching circuit, and the like. When the resistance of the thermistor RT changes with the temperature of the measured object, the two points of A and B will have a difference signal output, which is amplified by the FC3 operational amplifier. The VD1 ~ VD4 diode bridge is rectified to the base of the transistor VT1, when the difference signal reaches a certain value, the transistor VT1 is turned on, the VT2 is turned off, and the small bulb HL does not light; at this time the rotational potentiometer RP. There is no difference signal between the two points of A, B, and the transistor VT1 is turned off, and VT2 is turned on, and the small bulb is bright. If the potentiometer RP rotation angle is measured in the temperature scale, then the temperature of the measurement body can be read when the lamp is lit. The RT can be 20 "CΩ value of 10 kΩ, which is used as the temperature of the temperature in the metal tube, which is taken from the metal tube with two leads. When used, the temperature of the temperature is placed in the measurement site, swirled When the RP, the indicator is the light, the temperature scale refers to the pointer is the temperature measured. Google Translate: Electronic thermometer circuit as shown. It consists of medium-gain op amp Fc3, negative temperature coefficient thermistor Rt, VD1 ~ VD4 diode bridge rectifier and VT1, VT2 switching circuit and other components.When the thermistor resistance value Rt of the temperature with the measured changes in the object, A, B will have two points difference signal output, this signal by Fc3 operational amplifier. vD1 ~ VD4 diode bridge rectifier added after the base of the transistor VT1, when the difference signal reaches a certain value, the transistor conduction VT1, VT2 end, do not light a small bulb HL;. then rotating potentiometer RP So that A, B no difference between the two signal output, the transistor vT1 end, VT2 conduction, small light bulb to light RP if the potentiometer rotation. In Mind The Temperature Calibration, THEN You CAN Light Bulb, The Reading Out The Temperature of the Measure Object.rt 20 ° C, Can Be Used for the 10kΩ Thermistor Resistance al tube, with two wire leads from the metal tube. When used, the sensing device on the measured position, rotating RP, the brightest light, the pointer shall be measured within the meaning of the temperature of the temperature scale.

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