Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It can be replaced with LED with appropriate series resistor. Transistors may be modern equivalents.
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...