Touch sensitive pad

[frankwas]

Hi All.

I am really intereste in building a touch sensitive controller for my room. But, I want to make it look awesome. I was wondering if it is possible to make a circuit that can pick up touch through glass or plexiglass or similar? Does anyone know where I could look for a circuit or anyone point me in the right direction. I looked for a few circuits, but they all require the person to physically touch an open metal contact.

Regards,

F.

 

[jgeidl]

You might think about a light curtain instead...like a garage door opener but a lot smaller.  Instead of the touch to the surface the trigger is tripped by passing your finger through the light curtain.  With this approach you could trigger the switch by passing anything through the light curtain, not just a finger.

Jim

 

[Tkjas]

Light Curtain's a good idea.

There is a very complicated way to amke something like u said.

You could also build a  short range radar/ or Ultasonic tracker that would send out waves to a range of 1cm-5cm? depending on what's between it. When something is near, the switch would be turned on

Another one, I haven't seen it for more than 10 years!!! I think it's that if u touch a pin on a MOSFET?, the circuit would turn on the switch. This doesn't need something to complete an open contact, but just the capacitance of ur body.  ;D

-Tkjas

 

[frankwas]

Oh ok. Thanks for the quick replies. I think the mosfet idea will work well. The light curtain will also work. I think I first need to look around for a bit and see what I can find. Thanks for your input guys!

 

[Theatronics]

Check out a product called Q-Prox
http://www.qprox.com/products/touch.php

Sensors can pick up finger touches through thick plexy.
Edge light your plexy and etch symbols into it for a amazing
display/ control panel!

-Mike

 

[Tkjas]

Nice find, and solution to the problem!!!

The only thing I don't see are the price for the components. Know what they are?

I haven't found any good circuits from my papers, or the internet.
Here's a project that when u touch the base pin of a PN2907 (PNP) transitor, the switch would be turned on. http://www.discovercircuits.com/PDF-FILES/5vmom1.pdf#search=%22touch%22

 

[Tkjas]

Here's a whole stack of Touch activated switch circuits!!!  ;D
http://www.discovercircuits.com/DJ-Circuits/touch-sw-circuits.htm

 

[Theatronics]

Tkjaz,
    Looks to be about $3.00 us.

Digikey Link:
http://dkc3.digikey.com/PDF/T063/1898.pdf

Might be able to find them cheaper from other sources.

-Mike