This Project Incorporates a Pair of Two 555 Timers in an Interesting Way
The 555 timer is one of the most well-known integrated circuits that has ever been produced, owing to its simplicity, low cost, and the sheer number of potential applications it can be used in.
Typically, the 555 is combined with buzzers to produce sirens or other waveforms, and it has also been used as a switch in conjunction with light-detecting sensors. But for Instructables user lonesoulsurfer, he was able to create something entirely different by combining two 555 timers with a couple of decade counters to produce captivating patterns of LEDs.
The core of this project, as already mentioned, is a pair of NE555 timers, which each toggle their output frequency based on the values of two capacitors and a potentiometer. From the output pin, a 4017 decade counter was connected that increases its value at each clock pulse a total of ten times before rolling back over to 1. The 9x9 grid of square LEDs lights up via a matrix of columns and rows, with a decade counter + 555 dedicated to either all columns or all rows. Finally, power is provided by either a 9v battery or a reused mobile phone battery, boost converter module, and a USB charging module.
For the PCB, lonesoulsurfer went with a 2-sided board that is split into three main portions. The first, and most apparent, is the large grid of LEDs at the center as well as many passive components surrounding it. Just below are the controls for adjusting the output frequency for the X/Y 555 timers via potentiometers and buttons for switching them on/off. Finally, the underside contains the timers and 4017 decade counters while the power management components were added separately.
With the PCB now completed, the last step of building this project was to make it look a bit nicer by fabricating an enclosure. The case was fashioned out of several pieces of wood that had grooves cut so they could slide together whereas the top was created from an acrylic sheet and later decorated with yellow labels/text.
At last, everything was completed and lonesoulsurfer could enjoy his creation by experimenting with how making small changes to the X and/or Y axis speeds could impact the resulting pattern shown on the matrix. To watch this process and see how this device was created, you can watch its video here on YouTube.