| 摘要 |
<p>A gas detector (A) comprising a Wheatstone bridge circuit (21) in which a series circuit of a contact combustion type gas sensor (1) and a load resistor (R1) and a series circuit of a resistor (R2), a variable resistor (VR1) and a resistor (R3) are connected in parallel, a circuit (26) for applying a pulse-like heater voltage generated by switching the DC voltage of a DC power supply circuit (25) through a transistor (TR1) to the Wheatstone bridge circuit (21), an integration circuit (22) for integrating the voltage at the joint of the gas sensor (1) and the load resistor (R1), an integration circuit (23) for integrating the voltage at the joint of the variable resistor (VR1) and a resistor (R3), a differential amplification circuit (24) for amplifying the differential voltage between the output voltages from the integration circuits (22, 23), and a signal processing circuit (20) for determining the concentration of combustible gas from the output voltage of the differential amplification circuit (24).</p> |
