This optical counter was found in a 1964 Electronics Design. It makes use of an uncommon optocoupler today, using emission lamp and a phototransistor.
This circuit was found in a Popular Electronics from the 90s. The components used are all common...
This circuit is from a 60's documentation. The circuit uses components from the era and serves to...
One pulse in the output is produce at each 5 pulses applied to the input. The circuit uses CMOS...