This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
This circuit was found in a 1997 documentation. The signals are adjusted in a double 555 (556) and the...
This circuit uses only transistors, producing a pseudo-sequential effect with 6 LEDs. The circuit is...
This circuit was found in an American publication from the 70s, but it can be assembled with more...