A brief history of direct-reading frequency meters

摘要

Digital frequency meters (counters) were not widely used until integrated circuits reduced the cost in the 1970s. Imagine even a three-digit frequency counter implemented with valves. You'd need four twin valves for each decade counter, four for each display latch, five for each display decoder and eight more for time-base division. Plus another three for the power supply. That's a total of 50 valves!