GB1375869A - - Google Patents

Abstract

1375869 Measuring peak voltages BODENSEEWERK PERKIN-ELMER & CO GmbH 16 Nov 1971 [17 Nov 1970] 53198/71 Heading G1U A peak integrating arrangement for gas chromatograph signals comprises: a base line drift compensating circuit, Fig.1, including an integrating feedback loop 28, 30 which is periodically rendered operative by pulses (controlling switch 26) from a timing pulse generator 34 and whose feedback signal is subtracted from the incoming gas chromatograph signal (10), before the latter is passed to the peak integrator ADW, to maintain the base line at zero; and a peak detector, Fig.2, which senses when a peak occurs and thereupon activates a control circuit 40 which (i) renders the peak integrator ADW operative, and (ii) blocks (gate 36) timing pulses to the switch 26 to prevent erroneous adjustment of the drift-compensating feedback signal during the peak. The peak detector comprises a zeroing network 46, 52, 58, similar to Fig.1, which also receives (42) the gas chromatograph signal and which adjusts this signal to zero at each timing pulse. The adjusted signal (B) is passed to an integrator 68, 70 which is reset to zero immediately after each timing pulse, so that only on occurrence of a peak in the gas chromatograph signal will the integrator output (C) rise sufficiently to trigger positive or negative threshold circuit 74, 76 and thereby activate the control circuit 40. The peak integrator ADW comprises a voltage-to-pulse frequency converter and a counter.