This circuit was obtained in an old Popular Electronics. It makes use of quite common components. The speed of the effect is set to R7. The circuit drives 20 LEDs.
This power stage with two counterphase transistors and coupling transformers was shown in Radio...
This circuit was obtained from an Electronic Design from 1964. Transistors admit modern...
This simple indicator was found in a 1980s American documentation. The circuit uses an operating system...