Low Budget TouchScreening ?

IntrepiD One writes: "I need to create an information gathering interface (preferably touchscreen) in a lobby area, but my budget is very low. I have looked at touchscreen add-ons (150-250 US$). Also, I want to create the interface in an X environment to add more flexibility. Before I go off and reinvent the wheel, does slashdot have any input." Any ideas for an inexpensive way to get input put in?

Comments

What do you mean by cheap?

[human bean]

If you mean that you have more time than money, read on. Otherwise just buy the thing, and pay the price.

Consider making a grid of IR-LEDs (say top and left side)and photodiodes (bottom and right side). Build small adressing circuit run from parallel port of PC to individually strobe LEDs and see which detectors do not react. Software from there.

The venerable lightpen is even cheaper, has better resolution, and can be hacked together in moments.

Epoxy three piezoelectric tranducers (bottom left, top left, bottom right corners) on a monitor tube, attach to a/d circuit, have software monitor for vibrations from finger touch (yes, I know it can be done with only two sensors, but three makes the software much easier...)

If you can live with defined areas, get some thinly aluminiumised Mylar, form touch areas and circuits between them, then use those cheapie lamp controllers (60 cycle crossing detectors) to make data for parallel port.

I've never tried it, but I have observed change in capacitance in a monitor tube if you place your hand on it as the beam sweeps across. Build simple cap meter on front of A/D converter and then see if software can decipher changes in position.

All I can think of. Anybody else?