thermometer radiation circuit

Published:2011/5/1 23:39:00 Author:Christina | Keyword: thermometer, radiation | From:SeekIC

Detection device is the PbS photoresistor, it can detects the surface temperature higher than 100 ℃. TR1 ~ TR9 are the three-step amplifier that is installed on the detector. The bootstrap effect of the off-bias circuit makes the input voltage match with the radiation monitor device (61SV)'s 300kΩ impedance. Levels were added the bias to minimize the noise. When the ambient temperature rises, thermistor with the 2kΩ negative temperature coefficient adjusts the gain, to compensate the lower of the radiation detect device's sensitivity. The last stage of follower drives the main amplifier and instruction meter. Radiation detect device outputs 0.3mV, and this voltage gets through the pre-amplifier then becomes 1mV, the main amplifier outputs 20mV, it is in the range of 200uA ammeter's most sensitive range (deviation in 10%). This circuit has five ranges, the temperature range is 100 ~ 500 ℃.



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