Study on peak detecting and holding circuit for measurement system for plume transmittance

Two kinds of peak detect and hold circuits for measurement system for plane array solid engine smoke transmittance are proposed. A monolithic peak detector named PKD01 is used instead of the peak detect and hold circuit consisted of comparator and sample and hold circuit for channels of laser and infrared to decrease the error generated by the delay time of comparator and the droop of voltage. For the channel of visible light, the nonlinearity of diode for small signal can be ignored owing to the preposed amplifying circuit. A combination of PKD01 and the preposed peak hold circuit makes it possible to guarantee low droop rate. Schottky diode and polyester film capacity are used in preposed peak hold circuit to gain the slew rate of peak detect and hold circuit. The test result shows that the improved peak detect and hold circuit can hold the peak voltage of measurement system for plane array smoke transmittance steadily, quickly and accurately.