AC/DC Power supply with no neutral ???

[rmjr]

Hello,

I am working on a home automation device where I need low powered electronics within the electrical box of a household switch. Typically we have the line and the neutral wires available in the box. Therefore a small AC/DC power supply would use the existing 120VAC line as the input to a 5VDC power source as shown in #1 of my attachment. The power supply I would use is the following:

http://www.micropowerdirect.com/Page...%20MPM02V.html

The only problem is that sometimes in my switch box I don't have the line and the neutral wires!! In this case I only have the line and a return wire which will connect to the light. However, in this case, I still need my power supply in the switch box to provide the +5VDC as shown in diagram #2 of my attachment!

I have heard that such issues are possible by using the line wire only. My question is:

- Can someone explain to me how this can be done?
- Does someone know of any off-the shelf power supplies that would handle this connection!

Thanks all for your help

[electroyas]

This problem occured to me too, is there any method to resolve this issue? Apart from line and ground which will go off the trip swich probably..