Although this project doesn't fall exactly under the category of photo projects, the result can still
be beautifully staged on film. This time it's about LEDs and how to arrange them to chase lights with a simple circuit. The core elements are the integrated circuit NE555 and the decade
counter CD4017. Here the NE555 is switched as a stable flip-flop to drive the decade counter, which controls the LEDs. The frequency is set via the dimension of the resistors at pin 7 of the
NE555 and the capacity of the electrolytic capacitor. The following shows the circuit and its structure on an experimental board.