ALU Construction: Connectors and LEDs
As mentioned in earlier posts I'm basing my construction around 55 x 40 hole pad boards which fit my designs quite nicely at the right sort of size I'm looking to construct at. The connectors are right angled box headers and are simply soldered down to the back of the boards whilst the LEDs run along the front. The LEDs themselves are 3mm 12V types so that an additional resistor is not required (which would make the 'crammed in' Logic unit design even more tricky) and to make construction a bit more manageable each LED sits in a right angled holder.
Speaking of the LED holders, I was hoping to get hold of the ones that can be joined together to keep everything nicely lined up but was finding these tricky to get a supplier for so plumbed for the regular 'free-standing' ones in the end. I found, after much head scratching, that the easiest way to get everything to line up was to place each holder with LEDs fitted on to the board and then place packing between and behind each (braced against a strip of non-soldered header pins) and then solder the whole lot in one go.
I had a go at the simpler Arithmetic Card LEDs first and here's the result (with design diagram for reference):
So, after all that soldering how many LEDs survived? Well, all of them as luck would have it ... appears my soldering skills aren't as dodgy as I thought (or LEDs have become tougher with advances in technology) ... believe as you will ;) I've taken a video of the LEDs on the Logic card being tested ... you'll just have to trust me that the others work as it's not all that quick to take videos, run them through iMovie and then upload them to YouTube:
That's enough for this post ... it always surprises me how much solder I get though and this has been no exception so far and there's much, much more soldering to go. Before I do add more to the ALU cards though I'm going to take a small break and put a bit of thought in to how I'm going to connect the cards together.