weird discovery

benol · Post by **benol** » Mon Mar 26, 2007 7:17 am

You know those mouse touchpads on laptops that only work with your finger, well I discovered something cool. if you take a battery and move the positive terminal on the touchpad, the mouse moves!!!

jeroen · Post by **jeroen** » Mon Mar 26, 2007 7:21 am

wait.I don't think this has anything to do with the battery. IT'S SENSITIVE TO TOUCH SO ALSO TO THE TOUCH OF A BATTERY. IT MIGHT AS WEL BE A PEN

benol · Post by **benol** » Mon Mar 26, 2007 7:22 am

it's not touch sensitive though. try touching it with anything but a battery or your finger. it doesn't work.

jeroen · Post by **jeroen** » Mon Mar 26, 2007 7:24 am

try using metal. Or a risistor. It's prob just measuring conduction.

benol · Post by **benol** » Mon Mar 26, 2007 7:28 am

nope. just batteries and fingers.

arfink · Post by **arfink** » Mon Mar 26, 2007 7:47 am

Well, it makes sense, since detecting a positive voltage ain't that hard. Some time take a volt meter and see for yourself, a human being has a voltage potential! This is because our nervous system runs on electrical impulses, so things like our fingers, which have nerves very near to the skin, can have a measurable voltage. If you try, say, your nose or the heel of your foot where your skin is very thick or the nerves are not close to the skin it won't work as well. This should now give you a pretty good idea of why they have special pens attached to the little units where you slide your credit card and sign on the screen.

dudex77 · Post by **dudex77** » Mon Mar 26, 2007 8:44 am

benol wrote:You know those mouse touchpads on laptops that only work with your finger, well I discovered something cool. if you take a battery and move the positive terminal on the touchpad, the mouse moves!!!

cool crap ive been trying to find something that would work for years now i know

atari2600a · Post by **atari2600a** » Mon Mar 26, 2007 8:50 am

Just get anything that's not pointy & it will work. Grab a rubber foot from something & try that.

atari2600a · Post by **atari2600a** » Mon Mar 26, 2007 8:52 am

Oh, & the wire on the styluses on touchpad CC units are just there so people don't take the pen.

benol · Post by **benol** » Mon Mar 26, 2007 8:55 am

atari2600a wrote:Just get anything that's not pointy & it will work. Grab a rubber foot from something & try that.

doesn't work

Unidentified Assilant · Mon Mar 26, 2007 9:12 am

Cheap Stylus.

benol · Post by **benol** » Mon Mar 26, 2007 10:11 am

I think you guys think I'm talking about touchscreens. I'm not. I'm talking about the touchpad on laptops for mouse control.

tom61 · Post by **tom61** » Mon Mar 26, 2007 6:16 pm

Touchpads use capacitance: http://en.wikipedia.org/wiki/Touchpad

limpport · Post by **limpport** » Mon Mar 26, 2007 7:04 pm

Humans give off a tiny bit of electricity all the time (at least when we're alive). The pad on the computer senses this, and responds accordingly. That's why the battery works also.

There are a kind of table saw that shut off (ie:punch metal rods through the blade to stop it cold) when you touch the blade. Great safety feature. My school may be getting one soon.

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