When I design anything with multiple components that assemble to form a major end result, I tend to work backwards off of my design goals.
The number one goal for this was durability via the rigidity and reliability of the LED panels. The best and most durable option was to create actual circuit boards (PCBs) to solder the LEDs directly to. Attach those reliably by some manner to the garments and we would be in business.
For the ease of assembly goal along with the strength goal, I would use nylon nuts and bolts to attach the PCBs to the garments.Same 8 channel MOSFET sequencer, same fireman's pants
, and at that point a still to be determined black pullover top.
For the colors, I agonized over the decision. The sequencer is 8 channels with multiple patterns so I wanted to stick with two colors in a direct linear pattern in order to get the full sequencing visual effect. I did blue/green last year and LOVED the futuristic, TRON look that it gave.. but was reluctant to do the same thing. I considered everything.. pink/green, red/yellow, blue/purple.. but in the end.. gave in to the blue/green again.
First, the PCB/LED panel design.
For the battery source, I planned on using the same 18v battery pack since I knew from the previous design that multiple chains of 5 LEDs using a 100ohm-150ohm resistor would give me the perfectly sized grid that I was looking for. Using the LED wizard,
I plugged in my 18v source voltage, a 3.2v forward voltage for the blue/green LEDs, 20 mA forward current and 35 LEDs.. and bam.. 100 ohm / 1/4w resistors. Easy enough!
After doing some internet searching and reading, I found the software program EAGLE by a company called CadSoft.
It's pretty much the Adobe Illustrator for the PCB design world and a relatively easy to use and very industry accepted/standardized PCB design program. Not only is there a free version of it (or readily available cracked versions of the full program you know, if you were in to that kind of thing..
), but all kinds of free training videos on YouTube
and tons of chitter chatter/instructional documents on the net.
So, I downloaded, installed and began walking through the YouTube videos to learn this thing. It was fun! It honestly felt just like learning to use an Adobe program. You start from the beginning and just work up.
Since last year my panels were 2" x 7", I wanted to stick with that height but have them a little longer in order to wrap around my legs for better visibility as well as the design goal of MORE LIGHTS! They needed to allow flex.. so I would have to use multiple panels in a row. I decided on using 3 - 2.25 x 3.25 (roughly) panels in a row for each channel containing 7 rows of 5 LEDs connected in series. This would give me 35 LEDs per PCB, or 105 LEDs per channel per leg for the pants and 35 LEDs per channel per arm for the top. 2,240 total LEDs divided among 8 sequenced channels. 4mm holes on all 4 corners for attachment.
The first step is designing your schematics graphically:
Then, you hit a button and the program converts it into an actual PCB board. You drag and drop the pieces where you want them, run the trace routes, add some silkscreen and voila! You have yourself your very own custom circuit board: Yes.. I did make a mistake on the silkscreen layer that wasn't caught until after it was submitted. Gold star to the first person that catches it.
I did some research, and used a company called Silver Circuits
for the PCB fabrication. The total cost delivered to my door came out to $2.33/each for 130 of them. I made enough to do my project and a few others. Really not a bad price for your own custom panels! So.. here is the finished fruit of my labor in designing my first custom PCB:
WOOHOO! Such a cool feeling to see your own custom work immortalized in a shiny green PCB, I have to admit. Now.. for the fun part.. the soldering and actual construction!