LED Edge-lit Sign
My son and I "got busy" playing with tools today. The first thing we did was put 24 red LED's on a solderless breadboard, so that there are two different strings of 12 led's in parallel, connected to an ordinary AC plug through a 1K resistor and a .22uf capacitor.
Viola, there's light and no smoke! The next step is to shape the plexiglass. I cut out a 4" x 6" piece of 5/8" plexiglass for the project, then John and I clamped it in the milling machine and created a 1/2" wide slot across both long sides of the plexiglass.
After that, we changed the 1/2" milling cutter to a 3/16" cutter, and bored a 3/16" hole every 1/2", centered in that groove we just cut, so that there are twelve holes top and bottom.
The next step is to trace John's name off a paper template onto the plexiglass, through the protective paper film glued that's glued to the plexi. We used a dremel with a diamond point to do this.
Now we had to deepen the cuts to about 1/3 to 1/2 the thickness of the plexiglass and we dremelled that out too using a spiral barrel cutter. I did most of this part because John got very bored with how long it was taking.
And here is the finished piece of plexi - a slot across the top and bottom, John's name machined into the depth of the surface, and 12 holes bored top and bottom.
I'm sure all of you are scratching your head thinking... what the heck?
With all the tedious machining done it was time to solder up two LED boards, and I corralled John to help solder, since I taught him how to solder on Christmas. He still needs a lot more practice but I figured he can solder the LED boards together and after he heads off I'll clean up the joints later. So, here is the first board:
With two boards soldered together, John and I wired them up to the solderless breadboard so that the LED boards are in parallel, polarity facing in opposite directions, both in series with the 1K ohm resistor (the cylindrical thing with stripes in the lower right of the pic) and the capacitor (green thing in the upper left of the pic). Because the picture was taken off-axis of the LED lenses, they're difficult to see that they're illuminated but they are.
Finally, we slapped the LED boards onto the plexiglass so that the 12 LED's per board are inside the 12 holes top and bottom, hence two boards - they face each other, shooting through the plexiglass at each other - the light interrupted and refracted by the cuttings of John's name into the plexiglass.
The picture doesn't do it justice, and there is a protective, opaque film on the back of the plexiglass I haven't removed yet because I anticipate having to machine John's name a little deeper and it turns out, I'll have to do that.
Once it's done, I'll build a wooden frame to surround the whole thing and hide/protect the resistor and the capacitor, so it's safe and self contained. Then John can hang it on his wall and enjoy it :)