How do I tap 5V D/C from a single live wire A/C from a light switch without turning on the light ?
Something like the attached picture ...
Stanley:
How do I tap 5V D/C from a single live wire A/C from a light switch
Very carefully.
Seriously: If you don't know how, maybe you shouldn't be doing it.
It depends on what sort of current and if you need isolation. But if you have to ask about it then no you can't do it. Or at least you should not. Ever seen the Darwin awards?
Some guy attached a lot of helium balloons to his deck chair, and he floated up into the air with a shotgun in his hand to burst the balloons if they got too high.
Needless to say, the system did not work the way he planned.
the way he planned
Although "planned" might be too kind a word: "expected" maybe? Or even "hoped"....
Stanley:
How do I tap 5V D/C from a single live wire A/C from a light switch without turning on the light ?
How current flow on only single wire?
Connect a 5V DC wallwart in parallel with the light bulb.
http://www.dipmicro.com/store/DCA-0510
When the light bulb gets power, the wallwart gets power.
BillHo:
Stanley:
How do I tap 5V D/C from a single live wire A/C from a light switch without turning on the light ?How current flow on only single wire?
Zen-power
CrossRoads:
Connect a 5V DC wallwart in parallel with the light bulb.
Switching DC Wall Power Adapter 5V / 1A - dipmicro electronics
When the light bulb gets power, the wallwart gets power.
But OP need 5V DC without turnung on the light
JimboZA:
BillHo:
Stanley:
How do I tap 5V D/C from a single live wire A/C from a light switch without turning on the light ?How current flow on only single wire?
Zen-power
It's those pesky Zen diodes again, isn't it?
BillHo:
CrossRoads:
Connect a 5V DC wallwart in parallel with the light bulb.
Switching DC Wall Power Adapter 5V / 1A - dipmicro electronics
When the light bulb gets power, the wallwart gets power.But OP need 5V DC without turnung on the light
Take out the lightbulb?
majenko:
BillHo:
CrossRoads:
Connect a 5V DC wallwart in parallel with the light bulb.
Switching DC Wall Power Adapter 5V / 1A - dipmicro electronics
When the light bulb gets power, the wallwart gets power.But OP need 5V DC without turnung on the light
Take out the lightbulb?
Without access to both the AC line and neutral wires one cannot extract power for anything. It's like a bird sitting on a bare 2KV utility wire, nothing dramatic happens to the bird because there in no current path. 
Lefty
Riva:
How do the 'no neutral wire' X10 modules like this do it?
There is a signal path through the load. But with not enough signal to actually do anything with the load.
Riva:
How do the 'no neutral wire' X10 modules like this do it?
It get the return path through the lamp.
Incandescent (2-wire) switch can only control resistive load ?40W (incandescent lamp or halogen lamps, etc). It
cannot control inductive or capacitive Load (like: Fluorescent lamps?save-energy lamps etc).
Stanley:
How do I tap 5V D/C from a single live wire A/C from a light switch without turning on the light ?Something like the attached picture ...
What exactly are you trying to do? You could probably connect a 5 volt wall wart across the switch. You would get 5 volts and the light would not glow (because most of the power would go into the wall wart).
But if you turn on the light, the 5 volts would go away.
lastly, (don't take this the wrong way) but if you have to ask, you shouldn't even be messing with line voltage. One mistake could be your last. Be careful.
JimboZA:
Zen-power
Finally I understand what Zener diodes are. Something Zen-like.
Aoooohms law.
Henry_Best:
[quote author=Nick Gammon link=topic=157867.msg1183553#msg1183553 date=1364953051]
JimboZA:
Zen-powerFinally I understand what Zener diodes are. Something Zen-like.
Aoooohms law.
[/quote]
OK well that deserves a Karma++ if anything did... I really hate to use this word, but "LOL"
Thanks for all the replies...
I got the diagram from this URL: http://www.malaysiaswitches.com/technical-info/ and it is a working product with type approval and safety approval from local authorities..
But it does mentioned that it could NOT control CFL bulbs...