Digital display circuit for a photographic exposure meter

摘要

An analog-to-digital converter circuit for a photographic exposure meter includes a plurality of parallel connected transistors 51, 54, 57 and 60 whose bases are connected to the logarithmic output of a light measuring circuit A. The transistor collectors are driven by constant current sources comprising an equal plurality of transistors 50, 53, 56 and 59 having emitter area ratios of 1:2:4:8, whereby the collector voltages of the transistors represent a digital threshold conversion of the light measuring circuit output.