First: Build the LED board

1) Solder 112 IC sockets to the LED board

a. Look for a marking on the LED board, on the edge: (top)
Orient the board accordingly

b. Prop the circuit board up on something so the legs of the sockets will hang free (I use a roll of duck tape on it's side), then load a column of 7 sockets down each edge of the board (start with the far left and the far right column - just do it this way, trust me). It's not required but I like to orient the notch in the sockets towards the top. Make sure there is a row of holes at the top and bottom of each column left open for the header that will be soldered in later! And make sure there is a similar row of open holes next to the sockets. Be careful not to accidentally glop solder in these holes.



c. Place a precut length of duck tape over the sockets to hold them in place. You'll mess this up a couple of times and accidentally pull half of them out trying to adjust it and have to start over - but you'll eventually get the hang of it.



d. Run a thumbnail or coin along the duct tape to push it into the grooves of the sockets, and make sure they stay aligned with each other, that none of them are rocked to the left or right. I do the two sides at the same time (left and right) so that when I flip it over the first time, it is balanced and stays flat against the work surface. Now the sockets won't move or tilt while I'm soldering.



e. Solder each socket leg of both rows into place. Keep the iron hot and your tip clean and try to get into a rhythm. Keep a solder-sucker handy for when you glob things up. I use a magnifying lamp for this but you might have younger eyes than me. In any case, it never hurts to examine the solder joints afterwards with a magnifying glass to make sure there's no spatters of solder or other ugliness that could cause shorts.

f. Peel the tape off, reload, and repeat. Once you've done the first two columns, you don't need to keep doing opposite sides. I actually like to load 2 adjacent columns (the ones right next to each other) because it's easier to align everything.

g. Unless you're some kind of Olympic soldering champ you'll be doing this for a couple of hours, so get comfortable, make sure to have a soothing beverage nearby, and take lots of breaks to stretch.

2) Solder the female headers around the perimeter

a. flip the LED board so the sockets are face down.



b. Arrange the female headers around the led board to make sure you have them all. Depending on the parts you get, there should be 5 or so headers per side, for instance 4 16-pin headers and an 8-pin header per side, adding up to 72 positions per side. Horizontally there are 74 holes, vertically there are 72 holes. You only need 72 header positions in each direction, an equal number on each side, because the vertical headers go all the way edge to edge, the horizontal rows fit between the vertical columns. You'll see what I mean when you start laying it out.



c. OMG, the headers don't fit next to each other! This is where the file or sandpaper comes in. (Note: Don't do this late at night while your room-mate or partner is trying to sleep - they will kill you). Take each header between thumb and forefinger and hold it firmly against the file, and file down each end a bit. 4 or 5 scrapes, then check, then 4 or 5 more, repeat. Keep the piece as square as possible to the file. Try not to file all the way down to where the little brass contact shows through. If this happens, make sure not to put 2 of these next to each other or you'll have a short.



d. Do this for a long time, working your way around, fitting the headers next to each other, making a little pile of phenolic dust. Don't solder anything, yet. Just get the headers to fit nicely together, then clean up the dust.





e. Now take the 40-section male headers, and going around, fit the long ends into the female headers. It's easier to fit two male headers next to each other if you partly pull them out, first, and push them in at the same time. You can also use the file if needed to make a little clearance. Twist off the excess headers by pinching and twisting hard with your fingers at the seam, or use a snipper. Save these extra pieces of male header because you'll need them later!



f. Now the male headers hold the female headers in place, all lined-up. Clever, eh? They keep everything lined-up while you solder.



g. Flip this all over carefully, making sure it doesn't come apart, and put it flat with a little downward pressure to make sure all the header ends are poking through the holes in the board equally all around. Now carefully solder each one in place. Be careful not to melt the ic sockets while doing this - it's a bit tight in there. I actually cheat a bit and sort of glob the solder on from one side. These are a little trickier to solder than the sockets since the header pin is thick and the solder pad is very small. The globbing thing actually helps a bit. Remember this is also a mechanical connection as well as electrical, so make it sturdy. But don't get carried away and make shorts! Use that solder-sucker without mercy.



h. After soldering all four rows of female headers into place, gently remove all the male headers you just inserted and put them aside. You don't want to accidentally damage them while pressing in the LED bargraphs in the next part.

3) Insert 112 LED bargraphs into the sockets

This is harder than it sounds. You'll want to be rested and decaffeinated for this.



a. Each color may have different markings, heights, and length of legs. It is important to think about this when designing your LED layout. You may need to snip some legs and not others. I find they actually work best if you leave the legs a little longer than they need to be. This lets the bargraphs nestle against each other nicely despite variations ion the cases. If they are all one color, your task is simpler, and you can usually just pop them all in as-is. Keep in mind a plexi sheet and sensors will go over the LEDs, so keeping them all perfectly flat relative to each other isn't a requirement for the stribe to work and look nice.



b. Make sure you know the proper orientation for the color(s) you will be using. The best way to determine this is to use a 1.5V battery, or a multimeter set to test continuity (this will send just enough juice to light the led without cooking it). Put the + on the left leg and the - on the right leg of the nearest LED. If it doesn't light up, flip the bargrpah 180 degrees and try again. This is how you want your bargraphs oriented: [+] on the left, [-] on the right.



c. These are fairly cheap-o bargraphs which I selected for their price. If you want to pop for some really nice bargraphs expect to pay about $150-$200 for 112 high-quality ones, unless you can get them in bulk (1000+ units) and then they're $90.

Meanwhile, back in the real kit, sometimes the legs may be bent or distorted, as they're made of thin wire instead of thicker legs like the fancy ones have, and transported stuck into styrofoam instead of nice protective tubes. Just carefully straighten the legs with a pliers, and make sure they're all lined up nicely before trying to insert them in a socket.





d. Starting at one end of the column of sockets, gently align the legs in the socket, and push. At a certain point they will all line up and you'll "pop" the socket into place. 99% of the time this means it worked, but it's a good idea to check each one with a magnifier afterwards to make sure, especially the first few. Almost every dead led in my experience has been the result of a bent LED leg that either missed the mark or folded in half during insertion, when I thought I'd done it perfectly. It will be frustrating getting these all in at first but eventually you'll get the feel for when they're in place and when to push and how hard to pop them in without messing up.



e. Take your time with this. As each column is loaded, take a strip of perf-board, or a thin metal ruler, and lay it in the space between the columns, then press the columns against the ruler and vice versa to line things up. I considered stuffing something in here to hold it all together, but it looks fine without.

To remove the bargraphs if it becomes necessary DON'T PULL THEM OUT BY HAND - unless you really like poking yourself with multiple really sharp wires in the thumb and/or forefinger, all at once, real hard. Trust me, you don't need to experience this. Instead, gently pry each bargraph up from underneath using something flat and stiff like this pair of scissors.



f. If you do mess up, like rip a leg off an LED or something, let me know: I have extra parts. The stribe will run fine with missing leds or even missing entire bars, so you'll still be able to play with it while waiting for parts.





TADA! You're done with the LED board! Set it aside.

Just a note here: I'm never entirely confident I'm NOT about to accidentally gloop some solder into a socket or something by accident. I often bow to the gods of humility and put some masking tape and/or foam over any delicate area in question, especially one that just took me hours and hours of careful work to solder, hint hint. This is your call.

Now it's time to build the DRIVER board.