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How to make the simplest momentary touch switch? Answered

a single contact TOUCH SWITCH that turns on when touched and stays on as long as its being touched then turns off the moment its "un"touched. i'll use it for lighting up LEDs.

thanks in advance

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sound91

8 years ago

 Take two pieces of some material, luan, masonite, anything will work. Luan or cardboard would probably be the best in reality.  Then, cover the two sides in aluminum foil, and separate them either using fabric around the sides or straws.  Then, when pressed together, the aluminum foil touches and completes the circuit.

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steveastrouk

8 years ago

Do you not think he's really aiming for a touch switch with no moving parts ?

Steve

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Jayefuusteveastrouk

Answer 8 years ago

Hmmm. Yes after rereading it you're right.

How about.....

Simple:
Two layers of metal, some squares of aluminium cut from drinks cans would probably do the trick. Flattened well then sandwiched together but slightly seperated by 4 pads of milk bottle plastic, 1 at each corner. This would be a switch similar to the other one i posted, but when pressed lightly in the middle it would close the 2mm gap between the contacts. It's not a TRUE touch switch, but it's probably the simplest you could make without making a body capacitance touch switch.

Complicated:
OR if you want to build a touch switch that uses resistance instead of capacitance, I found a guide here.

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tsdgenJayefuu

Answer 8 years ago

Yep, kinda complicated.

I just found something out. Googled "touch sensor circuit" and found this www.siongboon.com/projects/2007-11-29_touch_sensor/touch%20sensor.gif
I set it up very quickly, rather shabbily if you may- and it worked!
Or so I thought.
I found out that my setup worked when I touched the sensor plate only because I was using my other hand to hold the terminals against the battery.

Its a very simple setup. I dont know why its not working. Still trying to find out. Its either the circuit really doesnt work or mine doesnt. Arrgghh...

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steveastrouktsdgen

Answer 8 years ago

Its a crap method IMHO. Using a CMOS logic gate will work better, tie the input of  an inverter high with a big value resistor, say 10M, make your touch plate a bridge, so that your touch "shorts " the bridge to ground.

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Jayefuu

8 years ago

You could try something like my rather crude drawing below. :D

black - cardboard
green - something springy like a piece of plastic milk bottle or drinks can
orange - copper tape, can get it from maplin


switch.jpg
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JayefuuJayefuu

Answer 8 years ago

Doesn't appear very big, click to enlarge :)