Touch Sensitive LEDs

[Newz2000]

Imagine a grid of LEDs (standard 3 or 5mm) placed closely together. For argument's sake, a 5x5 grid is fine, but really it would be more than that.

Can anyone thing of a way to make the LEDs touch sensitive so that when you touch one of the LEDs it sends a signal like a button press to a microcontroller (maybe via Schmidt trigger).

Should be able to be acomplished with hobby-level skills and tools.

[JPKNHTP]

-JPKNHTP

[Chris Smith]

Capacitance

[Newz2000]

http://hackedgadgets.com/2006/04/14/led-touch-sensor/

wow.... that video is cool. That's way more than I was hoping for, but that would be an interesting project.

[Sambuchi]

JPKNHTP that site... http://hackedgadgets.com/ is great.. think i just wasted a hour or two looking at some interesting projects.

[JPKNHTP]

-JPKNHTP

[philba]

fascinating stuff but the guy suggests that it would be easier to use a photo transistor/emitter pair than the LEDs. I suspect he is right.

now, combine the sensors with the disco LED stuff and there might be a fun project.

[jimandy]

Maybe I missed it somewhere, but would that thing work in a lighted room? The video suggests the room was dark.

[Newz2000]

Maybe I missed it somewhere, but would that thing work in a lighted room? The video suggests the room was dark.

He says no on his blog. He says that the ambient light ruined it.

He didn't give much detail though, so I can't help but wonder if he provided an adjustment on his op-amp's gain to account for the lighting if it would work.

Also, the video demonstrates the LEDs providing an analog response, but if a person merely wanted on or off, I wonder if then it could be made to work.

I feel this is too complex for my needs, but it's a really cool idea.

[jimandy]

Chris mentioned capacitance. I'm not sure if your application requres LED's. You may already thought of using a matrix of small metal pads as touch sensitive plates using CMOS gates as detectors.

[Gorgon]

Hi Matt,
Take a look at this chip from Freescale MC33794

I think you could make something out of this. I've got a demo kit named 'KIT33794DWBEVM', but as usual I have not had the time to tinker with it. I got it for free, but I don't know if it is available any more.

TOK