[PLUG-TALK] Electrical hacking: Touch-lamps

Bill Maine mainsys at SpiritOne.com
Sat May 22 22:22:52 UTC 2004


These types of devices usually have a capacitive switch where your hand
touching the device changes the capacitance causing the circuit to switch ON
or OFF.

The device in the cord merely changes the ON phase duration of the sine wave
from your AC outlet, that is the time period in which AC current is allowed
to pass. It rises through 90 degrees to positive and then descends through
90 degrees to 0 (zero) for 180 degrees. It does the same thing in the
negative direction. It has been years since I worked with electronics but it
uses a Triac or Diac to pass current through 60 degrees, 90 degrees or the
full 180 degrees in each direction of the AC current. Or you can turn the
semiconductor device (triac or diac) off so it passes no current.

I believe if I remember correctly a Diac only passes current in one
direction whereas a Triac will pass current in both directions. Look it up
on Google.

This is why no connection to the lamp is required. The switch is in the
cord, in series with the AC line to the lamp controlling the time period
during the AC cycle that current is allowed to pass to the lamp or other
device.

Thanks
Bill Maine
mainsys at SpiritOne.com

-----Original Message-----
From: plug-talk-admin at lists.pdxlinux.org
[mailto:plug-talk-admin at lists.pdxlinux.org]On Behalf Of Grish
Sent: Saturday, May 22, 2004 2:30 PM
To: plug-talk at lists.pdxlinux.org
Subject: Re: [PLUG-TALK] Electrical hacking: Touch-lamps

http://home.howstuffworks.com/question42.htm
http://home.howstuffworks.com/framed.htm?parent=question42.htm&url=http://ww
w.paia.com/touchsw.htm


Jeme A Brelin wrote:

>OK, you know those lamps that turn on when you touch their metal parts?
>
>I want something like that... but not exactly like that.
>
>I went to the store to see what I could find.  I found a couple of
>interesting products:
>
>Touch lamps.
>Touch lamp bulb socket adapters.
>Touch lamp outlet adapters.
>
>The lamps do what the lamps do.
>
>The bulb socket adapter has a socket that screws into an existing lamp
>bulb socket and a conducting tab that screws against the metal casing of
>the bulb socket to make contact for the touch-sensitivity.
>
>So far, so good.
>
>The outlet adapter, however, goes between the power cord and the wall and
>has NO conductor to attach to a metal part of the lamp.  But it still
>freakin' works.  How the hell's that?!?
>
>Mods:
>
>I don't like what it does, exactly.  First, it is designed to dim power to
>three levels.  Is there a reason they ALL do this?  Can I modify the thing
>so that it just turns on and off with touch?
>
>And what if I have a lamp with no metal parts, but would like to have a
>metal strip on the wall that is touched?  Is that possible?
>
>Let me know if you've got any ideas.
>
>Thanks.
>J.
>--
>   -----------------
>     Jeme A Brelin
>    jeme at brelin.net
>   -----------------
> [cc] counter-copyright
> http://www.openlaw.org
>
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>



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