An intrinsically safe explosion-proof sensor circuit is realized through a simple system. An intrinsically safe explosion-proof sensor signal processing circuit is characterized by comprising a sensor section for measuring a physical quantity of an object disposed in a dangerous place and a safety keeping circuit disposed in an explosion-proof case in a non-dangerous or a dangerous place and provided with driving and feedback operational amplifier circuits and a current limiting resistor connected in series with each signal line connected with the sensor section and with the output terminal and the negative input terminal of the corresponding operational amplifier.
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