Looking for certain kind of RS232 LED sign.

October 5, 2007 2:37 PM

I'm looking for a small-ish (under 12") LED/message board sign that I can drive from a computer (RS232) that would allow me to change the messages in real-time. All the ones I've found either run off 12v or are battery powered. Bonus points if it can beep on command, too.

I'm more or less trying to find some way of creating a visual cue that can be triggered by a computer to signify some action has been completed. I'm going to have three of these on one computer. Each display would probably say something like "YES", "NO", or "ERR" and possibly flash if possible. Making it beep would also help. I can't use the standard PC speakers as I don't think I can get three separate channels on three different speakers without any overlap.

posted by prggr to computers & internet (15 comments total)

Kinda pricey but I like their stuff Phidgets 20x2 LCD
posted by mphuie at 2:48 PM on October 5, 2007

Spark Fun Electronics has a bunch of serial LCD screens, although I don't think any of them beep.
posted by hades at 3:24 PM on October 5, 2007

I take it back--this one beeps, too.

These are all what I'd call "small", though, not "small-ish". And LCD, not LED.
posted by hades at 3:27 PM on October 5, 2007

What is the issue with running it off of 12V? You can get that from the computer's power supply.
posted by sebastienbailard at 4:26 PM on October 5, 2007

Yeah, there seems to be an unstated requirement about its power souce. Are wall-warts out?
posted by hattifattener at 4:32 PM on October 5, 2007

Oh yes, sorry. What I meant to say was that I wanted to find one that would just plug into the wall. All the ones I keep seeing require some sort of 12v or battery source. I'm looking more for an always-on kind of device.
posted by prggr at 4:42 PM on October 5, 2007

If you've found something that would work if only it had different power requirements, your best bet is probably to find a wall wart that provides what it needs, and make an adapter. Shouldn't be too hard--check Jameco, Mouser, Digi-Key and other electronics suppliers for power supplies that might work.
posted by hades at 4:48 PM on October 5, 2007

Ugh, should have previewed. Can't use the 12v off the computer as I intend to run this up to 18ft away, three different directions and I really don't want to have anything that requires opening up the computer. Ok, here's what I'm really trying to do in case anyone has a better idea than mine:

I have a computer that will have three scales and three barcode scanners connected to it at different stations. Software will read the barcode from a station the grab the weight of that scale. Once that has been completed and a valid weight has been read, I need a visual (or otherwise) indicator that the item on the scale can be removed. Our current system only utilizes one scale/scanner and so I use the PC speakers to designate when it is OK to remove the item. With three stations, I don't have that luxury so my best idea was to have some sort of LED sign over each station saying when it is OK, or not, or anything else instead of the audio cue.

Hope that makes sense.. should have put that up there in the first place. :)
posted by prggr at 4:48 PM on October 5, 2007

I always wanted to install one of these in the back of my car to send messages to other motorists.

"Honey, this guy will not stop tailgating me, can you get out the Car-talk-atron and tell him to **** ***!"

"again?"
posted by muscat at 5:38 PM on October 5, 2007

Nothing to add, other than -- please don't present your solution in public when next in Boston. Such electronic displays often invite terror and panic!
posted by ericb at 6:44 PM on October 5, 2007

I don't see a specific wall-plug solution for you on this site, but I've found cheap LCDs at Crystalfontz in the past. They also have a ton of accessory cables if you attempt to craft your own solution. Your question gave me an idea for a small project, so expect a LCD related follow up question soon.
posted by shinynewnick at 8:27 PM on October 5, 2007

You could use the signal from the computers to flash a light, if you like tinkering. Not sure if this could be as simple as wiring up an led or two to the sound-out headphone jack on the computer; you might need to use a comparator or op-amp.

What about giving each workstation a different pitch beep, series-of-tones, or sound effect?
posted by sebastienbailard at 9:01 PM on October 5, 2007

The poster is looking for LEDs, not LCDs.
posted by Artifice_Eternity at 11:11 PM on October 5, 2007

With that specific application in mind, I'd probably do this with a few 7-segment LEDs, a handful of 74HC595s, some piezo speakers, and an Arduino. Shouldn't cost more than about $45. Drop me a line at the address in my profile if you're interested in specifics.
posted by hades at 8:12 PM on October 6, 2007

The Arduino idea sounds like a good one. Instead of the 7-segement LEDs, I might just go with a pair of green and red LEDs (or maybe just a tricolor LED) along with a piezo speaker for each station. Just having a color indicator (green=good, red=bad) should be enough along with whatever noise I can make with the speaker. Now comes the fun part of digging into this whole electronics mess. I remember looking at BASIC stamps years ago, but Arduino sure seems a lot easier to mess around with.. might have to pick up a few to play with. :)
posted by prggr at 5:36 PM on October 7, 2007