How do X10 switches draw DC power from a live wire in loop-in circuits?

[juming]

Hey,

Older homes use a loop-in arrangement where the two wires coming down to a light switch are both live, and the neutral's nowhere near.
The X10 "plug n play" switches leak a small current through the light and draw their current from there... I was just wondering, how exactly do they do this?

Can someone point me in the direction of a full circuit diagram of how the X10 modules draw their DC power inline with the live??

Thanks :)

 

[Danger]

Sorry, man... I have no idea what you're talking about.

 

[NoTime]

For the pulg in units that something else plugs into. I think there is a fairly standard power arangement.

if you're talking about a replacement wall switch then I think there are two tap methods. One for power off just assumes a low load resistance, the other for power on uses a small inductor.

Don't have any X10 schematics.

 

[juming]

Danger: http://en.wikipedia.org/wiki/X10_(industry_standard )
http://www.smarthomeusa.com/info/x10theory/x10theory/#theory

NoTime: I'm basically trying to build an electronic light switch of my own, but I need a DC power source in the light switch, so I'm not after X10 specifically, just the same way they tap their power.

Thanks for the replies :)

 

[Danger]

Thanks for the links. The Wiki article isn't there, but the other one was about as comprehensive as anyone could want. I used to have the plans around somewhere for an intercom system that transmitted over the power lines, but that was just a straight signal over the system-neutral wire. This thing is in a whole 'nother realm. One question, though; it appears to be specifically tuned for 120VAC/60Hz. Do they make a European version as well?

 

[juming]

danger, yeh...
its not specifically tuned... that's just an american website :)

 

[Danger]

Figures.

 

[NoTime]

NoTime: I'm basically trying to build an electronic light switch of my own, but I need a DC power source in the light switch, so I'm not after X10 specifically, just the same way they tap their power.

I never got around to analysing how this was done.
But, you could pick up a cheap motion detector switch.
This would have all the power managment circuitry.
Probably cheaper than buying the components seperatly.