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 increasing C1.
Here is an interesting circuit to be used in physics demonstrations involving energy...
This circuit, obtained from a 1978 publication, generates damped signals and can be used in...
We found this circuit in a manual of optoelectronics from Texas Instruments. In it photodiodes or...