On Wed, 26 May 2004 02:03:12 -0700, roines reenig wrote
> Hi,
>
> I was just looking at this board that is intended to allow for
> remote control of a mains load. Meaning, let's say you've got a
> lamp. It's got just one wire coming in and one wire going out.
> That's the live-wire in, and live-wire out and in-between, you (the
> lamp in this case) are the load. This board goes in between the live-
> wire in and the lamp. This board appears to have some sort of
> processor, looks like a samsung 8 bit processor, some eeprom and
> some digital IO. I didn't get a chance to examine the board any
> further before it was taken away from me.
>
> Now, it's powering itself from the mains live-wire in and I presume
> grounding itself using the live-wire out, therefore increasing the
> leakage current. I assume that it's not leaking so much that a
> flourescent lamp would start to flicker. Any ideas how this power
> supply mechanism works? The CPU's very likely to be a 5Volt part, so
> they must be able to generate the 5 volt DC voltage and current from
> the mains. I realize that there are high voltage switching power
> regulators like the VB409 that could generate 80mA and regulated
> 5Volt from mains. Is that what they are likely to be using? Or do
> they have some special stuff since they don't have access to ground
> and neutral wires.
>
> Thanks,
> Roines
>
Roines,

If you're talking about a light dimmer, it steals power through the load
while the load is switched off.  This is stored in a capacitor.  If you look
at the voltage fed to the load with an oscilloscope you will find that the
load is never switched on 100% even at full brightness.

Randy


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