This circuit of starting lights for auto-race was found in an English documentation from the 80's. The LEDs must be of different colors, for greater realism.
This simple game in which the player has to guess the chosen position of the key was found in a...
This circuit was obtained from an English documentation from 1995. The operational amplifier has...
This circuit provides just over ½ W to a small speaker. We found this configuration in an old...