Touch sensor thingymabob button dohicky... (darlington transistor)

[crashwg]

A while back I recall seeing a website that had this little round metal disk looking thing that you installed in your computer to be your power button but the thing was that this thing was a touch sensor of sorts and not a machanical button like the usual...

I'm thinking about doing a project that would benefit the use of one of these things as long as they're not outrageously priced.

Anyone have a clue as to what I'm talking about?  Google doesn't 

[rugby1]

Is this what you are looking for?

http://www.xoxide.com/vl-system-touch-one.html


I bought one but haven't had a chance to hook it up... I don't like how it gets its power though... literally jamming 2 metal prongs into your ATX motherboard power connector...  I'm just waiting for a short.

 see review below

http://www.extrememhz.com/touchone-p1.shtml

[crashwg]

For some reason I don't think that's it...  I could verry well be wrong though.  I think it will work just fine though so I'm going to check it out.

Thanks

[D5A1AC]

Are you talking about something involving a darlington transistor setup? (Like 'touch lamps')

If so you could probably make your own with little effort.

[crashwg]

Are you talking about something involving a darlington transistor setup? (Like 'touch lamps')

If so you could probably make your own with little effort.

Touch lamp-like operation is exactly what I'm going for!  What I want to achieve is touching a piece of metal will connect two wires...

Oh, to heck with all this beating around the bush.  I was trying to keep things under rap so my idea wouldn't be taken nor would there be anybody interested in how it was going that would be dissapointed if it didn't go anywhere but trying to explain this without some details is getting hard.

So, anyways.  At this link there is a schematic for using an ir remote control to turn an xbox on.  As you can see, the xbox has 3.3v available durring standby which is what I would like to use.  Alternatively I guess I could use the 110v comming into the xbox if the 3.3v wouldn't cut it but I don't know exactly how that would work out and definitly wouldn't want to fry my xbox!

Also, I'm not decided yet on whether I wan't the eject or the power button to be activated by the darlington transistor but I doubt it would matter other than the fact that I might not use the 3.3v from standby if I were to do the eject because I don't need to push the eject button when the xbox is off so I could use any other voltages that are available when it's on.  As a matter of fact if I were to do that it would be preferable if the eject button didn't work when the xbox was off because then I wouldn't have to worry about the xenium os booting accidentaly.

So those are my thoughts.  Any help with setting something like this up would be awesome!

[D5A1AC]

Ok, well if you make up a circuit with two transistors in the darlington setup, you can use that circuit to make another transistor act as the 'power switch'.

Here's a good example:
http://www.kpsec.freeuk.com/trancirc.htm (Check 'Darlington pair')

You would have to replace the LED with another transistor (NPN or PNP, I'm not sure as I always get confused with transistors so that's up to you to find out  )

With this circuit you will have to have two bits of metal aligned closely and when you touch the two it's like holding down the power button on the Xbox. It will run off 3.3V.

If you wanted something that uses only one piece of metal then things go beyond my limited electronics comprehension ability. You may be better off modifying a commercial product if that's the case. On the other hand you could just get creative with the two pieces of metal. A small Yin-Yan perhaps? 

[D5A1AC]

It looks like you've lost interest/motivation for now, but I just stumbled across this

http://superpositioned.com/articles/2006/04/25/doorknob-touch-alarm

It may be of interest to you.

[crashwg]

It looks like you've lost interest/motivation for now, but I just stumbled across this

http://superpositioned.com/articles/2006/04/25/doorknob-touch-alarm

It may be of interest to you.

Pretty sweet!  Unfortunatly the extent of my electronics ability is putting a modchip in an XBOX and replacing LEDs in various things so I'm not sure if I'd be able to figure out what the components are nevermind set them up to work but perhaps if I take a class some day I'll come back to this and give it a go.