VACUUM TEST DEVICE Russian patent published in 1998 - IPC

FIELD: vacuum instrumentation engineering. SUBSTANCE: device is essentially measuring chamber positioned in solenoid. Basic members of chamber are flat heater made with the aid of heating thermal resistor and flat pyroelectric transducer connected to input amplifier installed with clearance to heater. Solenoid is supplied with pulsating current of 1 Hz frequency. Electronic circuit includes leak-measuring amplifier and leak-detecting amplifier of pulse signal tuned to the above-indicated frequency. Both amplifiers may be connected alternately to input amplifier. Heating thermal resistor serves as Whetstone bridge arm intended for independent measurement of pressure. Input amplifier includes field-effect transistor and operational amplifier and is made as differential amplifier. Main amplification of leak-measuring amplifier is created by means of at least two selective amplifying stages. Input amplifier has fitter which band envelops bands of leak-measuring and leak-detecting amplifiers. Heating thermal resistor is removed from heater surface open towards pyroelectric transducer within distance of about tenth fractions of millimeter. EFFECT: enhanced stability and sensitivity. 7 cl, 2 dwg