The peak detector tracks and holds, using the charge-storing ability of a capacitor, the highest output voltage from a transducer. Initially, the voltage on the inverting input of the comparator is at ground level. As a small voltage (0-5 V) is captured by the peak detector and presented to the comparator`s noninvertÂ· ing input, the output will swing high, which asserts the bilateral switch; clock pulses now pass through the switch to clock both the BCD and binary counters. The outputs of the binary counters are connected to an R2R ladder network, which functions as a digital-to-analog converter. The author of this great circuit is Mr. Roger D. Secura.
As the binary count increases, the R2R ladder voltage also increases until it reaches a point slightly above the voltage of the peak detector; at that instant, the comparator output swings low, which disables the bilateral switch and stops the counters. The number displayed on the 7-segment LED"s will represent a value equivalent to the transducer"s output.