GAS PICKUP Russian patent published in 1995 - IPC

FIELD: measuring equipment. SUBSTANCE: gas- sensitive resistor and inductance are connected in series into circuit of the base of a bipolar transistor. The inductance is used for creating negative resistance in bipolar transistor. A capacitor is connected in parallel to this circuit to define an oscillatory circuit together with the inductance and impedance of the transistor. A capacitor is connected to the collector and base of the transistor for creating short for alternative current. When gas is fed to the gas- sensitive resistor, resistance of the gas-sensitive material is changed due to chemisorption of gas molecules. As the result, inductive component of the impedance of the bipolar transistor is changed resulting in changing of resonance frequency of the oscillatory circuit. EFFECT: enhanced sensitivity. 1 dwg