Shawn Wilton wrote:

> They're probably just using a step down transformer, and a rectifier
> circuit.
>

No, he said there's no neutral return. It sits in series with the mains
supply
and the load. Maybe a zener to ensure a min voltage for the micro. That
way you're keeping a few volts to generate the stable micro supply from.
The touch lamp dimmers that came out years ago did something like this.
An internal diagram of one of those chips would show how it's done.
http://www.lsicsi.com/pdfs/LS7631_LS7632.pdf shows one of them.
David...

> 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
>>
>>
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