This is the best thru hole soldering practice kit you could hope for. It has around 130 components and a quality but busy PCB.
The instructions were fine although we chose to do the LEDS before the capacitors so they could lay flat while soldering them.
The schematic explains it all. It has two 4017 decade counter ICS and two 555 timers feeding a signal to them. Three buttons allow you to alter the connection with the second 555, a switch on a capacitor to change the speed and a third switch to give it diagonal controls as well as two potentiometers to control the display.
One 4017 is on the positive side of the LEDS and the rows and the other is on the negative side and the columns. So if you try to understand what is going on when it does a horizontal or vertical rastor that makes complete sense but when it goes diagonal you have to try to understand simple multiplexing.
For example if you want the LEDs in row 1 column 1 and row 2 column 2 why doesn't row 1 column 2 and row2 column 1 light? Yes that's multiplexing...
Lot's of fun with this kit.
Stay tuned:)