This circuit drives 4 sequences of 5 LEDs that can be of any color. The frequency depends on the characteristics of the photosensor. The circuit is from an 80's documentation.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...