Q.E.D.'s staff report on Touch Lamps .
How come if I gently touch my touchlamp then gradually apply pressure it doesn’t change? If I do it carefully enough, I can eventually get my whole hand on the base without the thing coming on. My lamp is probably 15 years old, that may have something to do with it.
And should we be worrying that a wiring fault in a touch lamp could electrocute us?
And more important, will it kill kitty? 
I suspect it’s designed to be sensitive to sudden shifts in capacitance, not to absolute numbers.
The oscillator is apparently sensitive to increasing capacitance. At our house, we’ve linked chains of six people and were able to trigger the light. I have my 4-year-old keep her hand on the lamp, and I tap her nose. Loads of fun for hours.
My cat has learned to operate the touch switch. It’s a fun way to get Mom up in the morning.
The circuitry attached to the metal parts of the lamp are completely isolated from the mains power. It would take an extraordinary fault for the lamp exterior to become energized, so both you and Kitty are safe.
USCDiver, the explanation offered by John W. Kennedy is correct. You don’t want the lamp to be too sensitive, otherwise it’ll be turrning on and off when you don’t want it to.
Yeah, but is such a fault less likely than electrocuting yourself with a toaster?
I don’t know. I’ll let you know next time Kitty fishes his pop-tart out of the toaster with a touch lamp. 
Pretty funny; I was just composing a GQ post asking about MY new touch lamp.
I remember seeing a touch lamp that had a planter in it’s base. You turned it on by touching the leaves. Would this require that the plant be watered regularly
Try one who’s learned to operate a touch-on bedside lamp with variable brightness. She thinks it’s wonderful fun. A pity she generally decides to entertain herself this way when we’re trying to sleep…
I have another question about touch lights.
I bought my mother a cheap one about 15 years ago (I was 12). It had three setting, bright, brighter and brightest.
When our old cordless telephone would ring, the lamp would turn on. What is the deal with that?
That’s a really interesting question. Back then, cordless phones used the 47/49 MHz band on something like 10 channels. When the phone rings, the base sends out a radio signal that the handset pickls up so it can ring too. I’d suspect that this signal was able to trigger the lamp somehow.
Thanks for the quick reply Q.E.D.
The phone is very old. My parents still use it, but the lamp is long gone.
I wanna touch-on toaster !
If a duck touches a touch-light, and quacks in alarm, would it turn off the Clapper® light?
“Ecology is…echo. Eco…logy is when everything bounces off everything else.” --Firesign Theater
I bought a set of Flying Lures®. I opened it up on the dock, and I haven’t seen it since.
I went on a golf trip, and I got delayed. Airport Homeland Security guys took my driver (made of armor piercing bullets,) and they never gave it back. I hope it helps Tom Ridge’s game.
Is there any way to fix these things? I’ve had two and both stopped working a few months after I got them. They would always stay on, which isn’t a problem unless you don’t have a switch and have to unplug it every time you want to use it.
I also had a cat who liked to turn mine on and off with his nose. At least he was nice enough to only do it when I was not asleep.
Touch lamps are a little extra hazard. Adding anything to such a simple circuit as a lamp greatly increases the number of ways it could fail. E.g., the cat knocks the lamp over you’re gone, so it’s now on and the bulb is against something flammable. A regular lamp wouldn’t have that danger. Some danger, just not a lot.
EtH, There’s a little info on touch lamp repair in the Repair FAQ. Do you know what a thyristor looks like and how to test it???
I note that further down the FAQ, there is mention of frequency change, but due to inductance not capacitance. So I guess there’s more than one way to get a cat to turn on a touch lamp.
If you want the plants to live, sure.
Ours stopped working a five or six years ago when a pet knocked it over, and I took it apart. I noticed a small gap in the printed circuit board, and I just dabbed a bit of solder on the break–the lamp has worked fine ever since. It’s plugged into a wall socket that has a wall switch, and we can turn the lamp on by flicking the switch a couple times–just once won’t do it.
The original answer was incorrect. Touch controls can be made in the manner described, but they are overly complicated and prone to drift. Instead, commercial units commonly use hum coupling. What is hum coupling, you ask? Anyone who touches the live lead of the input of a guitar or other audio amplifier, and heard the loud hum resulting, has heard it in action. For another, more sophisticated approach, see www.qprox.com
I have a plasma ball, (a glass globe with lightning) thats sound activated. when I pluged it in in the same room as mt touchlamp they interacted. when a sound caused the ball to light up the light would turn on or off. can anyone tell me why.