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LED display sign and ARM board group buy..

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Alan69

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single color led display boards

Preliminary ideas at the moment, this is more to gauge evel of interest instead of trying to set things up. With a Hamfest and a convention coming up, it could be several months before I move on this. Really I'd want to work on the board patterns off and on some anyway, to make them as adaptable as possible.


First thing would be an LED display. Something on the order of 1 or 2 lines x 16 or 20 characters. I'll work up a decent pattern, so it can be common pin RGB, single color, or separate RGB, and high or low density. That way you could make a larger sign with less cost with less LEDs, stuff only 1 color so you can get started cheap but then fill in the RGB later for full color, etc. There are places that do panels or batches of 8.5x11 boards fairly cheaply, so it makes sense to do in a larger quantity and split up the excess. Likely would keep the board single sided, you mount the LEDs, cut off the column pins, leave the common pin for the rows at 1/4", then do the next row etc. This leaves the common pins high, you then push cardboard on as an insulator, then solder a wire along for the common row connection. This leaves it a cheaper single sided board, as well all of the wiring being away from the LEDs so easier to protect and use it outside. I already have IR code and sign code etc, should be simple enough to work something up and make it fairly easy to use with an IR keyboard and remote and any other ideas we could come up with..

Actually looking at pricing, separate LEDs makes far more sense. 1000 single color LEDs seem to be going around $30 on ebay, so 3 colors RGB would be $90 or so, RRGB would be $120. RGB common package LEDs are more like $30/100, so ten times the cost. Might get a price break on a very large quantity, but likely as good of break for separate LEDs too. Seems like it'd make the most sense with separate, of course if anyone knew of a specific deal somewhere I'm completely adaptable.


Second is an ARM board. Seems like with a little work and shopping and doing a quantity of 15 or 20, could make something decent for $40 or so, and get 3 for $120 or $160 etc. There are some $60 or so Atmel ARM boards on ebay, so not a bad way to go, but I'd be looking for more like the 200 or 400 MHz ARMs. Preferably a clone of something out there with open software, not every bell and whistle but more than a target board and enough to learn on, and a little more substantial than a PIC or AVR. Of course I'm open to other ideas if someone knows of a good deal. I'm not finding any reasonably cheap and fast target boards, but I haven't looked hard lately so there may be something great out there. Heck there may be an open source design that I just haven't run into..


For just boards etc I'd probably just gauge interest and do the buy myself, then simply sell off to those interested. Not really looking to make a profit, just get mine cheap since quantity pricing makes a lot more sense around 10-20 than the 2 or 3 I want of each to play with. And from the topics on the board it seems some others might like this idea as well for one or both. For LEDs it could make sense to put together a very large buy if there's enough interest and we can find a good enough price break to make it worth while. The boatload of LEDs from China travels a little slower, but they are cheap..

Again, for sure it'll be a little while, but I find myself wanting something a little bigger but still desktop friendly to play with since the couple of decent signs I have from the company are 12 feet long and a pain to work with indoors. Probably would end up getting here around the middle or end of summer due to the lead time and things I have going on until early summer. Mainly I'm looking to see how many might be interested, and whether or not to even put in the combined RGB LED option.


OK did some looking, and found the board place again..

http://www.custompcb.com/

Around $200 for 20 single sided panels. It's easy to lay the row wires yourself, so that's the way to go vs a double sided board at more than 50% more. Each panel would cut in two and go together, for a 22" x 4" sign. Hmm I'll have to check, might be better to stripe it the other way, cut the 11" into three 3 2/3rds" pieces 8" wide, then chain together for 24" x 3 2/3rds". $10 for that, and should also be able to put 2 or 4 together and make up to a 7" by 48" sign at $40 with 4 boards. Then the LED costs of course, and drivers but they are relatively cheap compared to the rest. $200 is cheap enough I'd just order the boards, then organize a group buy on LEDs if desired, since they'd add up fast. Cheap enough to get from Ebay at 1000 per, but with 10 or 20 K or more there should be a better deal out there somewhere..


Mainly mentioning this ahead of doing the boards in case others have some ideas for extra features that should get designed in. Easy to do that now, can be a lot harder trying to add things in later.
 

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