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.
This configuration is from a 1987 publication, but it can be easily assembled today, as the...
This is a simple source indicated for powering low voltage projects on the bench. The circuit is...
This circuit is from Philips' 70s documentation. Transistors can be replaced by modern...