Saturday, September 13, 2014

6MMRPC: All hail Zagnut!

Zagnat is pleased
TL;DR: Buy cheap clamp lights for your own light box. 

This week I continued with some work on my light box. I have the box, I need better lights. One of my friends is very much into electronics and computers, and invited me to learn how to solder and make circuits (this came out of asking if a given LED strip was a good deal or not). An order for a bunch of LED bits and some perf board was placed and arrived earlier in the week. After work I headed out and did electronics.

Robert swears there is a patron god of electronic lighting, named Zagnut, that you need to appease.

Appeasement is through strange writings that look suspiciously like what technical folks call 'circuit diagrams' and 'Ohm's Law' (P=IR). The funny thing is that you actually need to do this stuff and figure out how much power (heat) is lost at certain key bits.....or it goes boom. Robert says that Zagnut definitely has some angry fire god in there and this explains the heat, melting, and potentially fire.

After chopping down the perf(orated) board with a hacksaw, you smear some solder/flux material on it, and place your circuit components (the yellow squares are the leds). The silver lines on the perf board represent parallel wires, so you place an led such that it acts as a bridge between the 'wires'. The led's have a *tiny* break on their back, so current is forced through the light inside, rather than just across the back (contacts).

The big magic part (you know, apart from the magic of light creation) is that you hit this with a heat gun, and eventually the solder/flux dries out.....then suddenly turns terminator style liquid metal/bright silver, THEN THE LEDS MOVE TO THEIR CORRECT LOCATION!! It looks pretty magic. Apparently the magic of surface tension with respect to the contacts, breaks, holes in the perf board, etc. But pretty amazing.

Afterward, you do some more calculations to figure out how big a resistor you need to avoid a fire, and then you do the more traditional type of soldering (with a bit hot pen and a coil of wire/flux stuff). Trying to do this with the circuit boards would be almost impossible as you'd fix one side on an angle, and not be able to fix the other side (imagine trying to nail a board to a solid floor from underneath it). Wires are then attached on the far sides of the perf board and light tested (hold breath here).

We decided to attach some crimp plugs to the lights so it's easy to hook them up to the power supply (harvested from an old computer).

Now, a couple of problems overall. It's not super cost efficient. I still have to pay Robert back, but I think it's going to be about 30 bucks. I wanted lights that were closer to daylight temp, which were around 50cent per, vs the 34 cent he uses which are very blue. If Robert didn't have all the hardware, this would be a lot more costly. Not super time efficient (this took most of an evening). It's also ugly with all the wires etc. The cables off the power supply don't give me much flexibility for positioning due to their shortness. The final issue is that these chips get pretty toasty warm, we scanned them with an IR temp sensor and it's around 60C for the small ones, and 85C for the large one (the resistor in particular). I plan on adding some aluminum backing for heat dissipation, but still....

It's fun, and interesting to though. I'm glad I learned/refreshed my knowledge of circuits. After all, this is pretty key infrastructure to our modern life. I'll post up some pics of what I actually got painted in another day or three, once the highlighting is finished.

1 comment:

  1. Refreshers are always good, now ya know what to do in case of the z-Poc!