We found this circuit in a 1986 documentation. It uses only LEDs, batteries, resistors and the power supply which can consist of 4 batteries or a 9V battery. The basic circuit uses two-color LEDs.
This circuit can be used for several purposes such as pulse counter, pass counter, roulette, etc....
This circuit is from Radio Electronics. The magazine no more exists, but the circuit can be...
We found this circuit in a French documentation from the 80's. The components used are still...