Comments on: Phototransistor multitouch with a twist

By: andre

andre — Sat, 06 Jun 2009 12:40:26 +0000

hmm.. maybe use the SMD phototransistors from smashed road light PCBs (the little squre transistor based PCB) … i have a load someplace, can i find them maybe and try it?

these can be purchased from various suppliers, and are often used on laser printers etc as rotary sensors.
-A

By: alex

alex — Fri, 05 Jun 2009 14:15:32 +0000

Hi(I’m the one that built this)

36chambers: Yes, it could be used for both of those things. Its probably not fast enough at the moment to be used for musical composition, but it could certainly work for 3d imaging. Albeit this one wouldn’t work very well, it doesn’t have a high enough resolution, like you said.

Darkfader, Ciberwizz: No, this one is not really multi-touch. The purpose of this was to test a bunch of different phototransistors to see which one worked best for my purposes. I am currently waiting on BatchPCB to send me my circuit board so I can begin work on a larger one. I have also tried using lasers instead of LEDs(so its an LLP effect instead of a DI effect). That works really well, but not so much for this specific example because the rows are spaced so far apart.

Thanks everyone!

By: CiberWizZ

CiberWizZ — Fri, 05 Jun 2009 09:32:19 +0000

Imagine this on the floor with an holografic image on top, you could interact in so many ways!!!

Making Virtual sculptors :D

awesome really :D

By: DarkFader

DarkFader — Fri, 05 Jun 2009 09:07:21 +0000

combobreaker!
I’m quite sure this isn’t touch though. Also, despite being sensitive, it’s not accurate enough.

By: kevin

kevin — Fri, 05 Jun 2009 02:24:25 +0000

Not quite sure if that’s really “multi-touch,” as I’m not seeing much variation of places he’s touching and places his hand is just over. That has got its uses, but probably not for multi-touch interfaces as we know it right now. Maybe putting a diffusing plastic above the sensors would make it more to what I’m thinking of, only detecting the actual points you literally touch.

By: jproach

jproach — Fri, 05 Jun 2009 00:52:33 +0000

adam: http://hackaday.com/2007/12/16/diy-led-multi-touch-panel/

It looks like an advantage of the phototransistors over LEDs is much more usable range (without having to amplify the signal, etc.).

By: Adam Ziegler

Adam Ziegler — Thu, 04 Jun 2009 22:54:41 +0000

http://hackaday.com/2006/02/21/low-cost-sensing-and-communication-with-an-led/2/

http://hackaday.com/2007/12/16/diy-led-multi-touch-panel/

-z

By: Adam Ziegler

Adam Ziegler — Thu, 04 Jun 2009 22:51:22 +0000

Wasn’t something similar done with just LEDs awhile back. Details are sketchy… but the LEDs ran at a frequency so that in the off state they could be used to sense light from surrounding LEDs that were on.

By: 36chambers

36chambers — Thu, 04 Jun 2009 20:21:33 +0000

Very good.

My 1st thought for application would be some type of air piano/synthesizer (musical interface). You could also use it to control the tilting of a plane, ie: Mercury Meltdown for wii

I may be wrong, but couldn’t this also be used as a sort of 3d imaging? Albeit the resolution is dependent of the amount and the size of the ptrans.