I spent the afternoon wiring up the LEDs of the shop timer. As we always say, behind every cool lighting effect are a LOT of wires.

The cathodes (negative) of all 42 LEDs are tied together, as the chip I’m using is a “source” (versus “sink”). If you look carefully, you can see that I started on the left — there are a lot more black wires. After that, I decided to streamline and use the leads instead. This made things easier when wiring up the center and right digits.

One the black was soldered, I did all the reds. There is a wire for each LED segment pair — a total of 21 wires (7 per digit). These were then tested and attached to their appropriate Molex connector.

When tying to the CD4026 there are two segments on the left of the chip and five segments on the right. I have 2 and 3 position Molex connectors on hand, so I use a two position on the left and a three + two on the right. To prevent confusion, I put a shrink wrap tag on the left connections (the blue tag) and yellow on the other side.

The wired are inserted in the proper order — they are not random. Check your data sheet for the pinout of the CD4026. Since the connectors are polarized (can only be inserted one way) I can just plug into my controller board and don’t have to label each individual wire. It makes more sense when you work on it.

Next up, building another controller board. Very similar to the Christmas Tree one, so hopefully it will come together faster.