This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at the end of the timer, erasing the other. The timing can be increased by changing C1.
We found this simple transistor tester in a French publication in 1981. It uses a common analog...
Who is faster? or reaction game are other names for this circuit that we find in old...
This circuit is from an 80's component manual. The components are from the time, but the circuit...