Microcontroller power from series 120v bulb connection (X10 style)

[bsculley]

I had a tough time coming up with the title for this post. I am in the process of replacing the X10 switches in my home with WiFI enabled switches, like Sonoff 10A.

I ran into a problem though; some of the lights in my house are wired so that only two wires come into the junction box, meaning that the X10 is getting its power from being connected in series with the lightbulb! Even more weird is the fact that the switch continues to work whether the light is on or off, meaning that the switch is able to power itself from the current passing through the filament when it is turned off.

I don't pretend to understand how this works, I'm just describing my observations. What I need is a way to develop 3v3 or 5 volts from this type of hookup in order to power the microcontroller.

Thanks for any ideas.

 

[dr pepper]

Welcome.
This is or was a common way to power a dimmers witch, the circuit draws so little current that the lamp filament doesnt light when switched off, however on leds this can b e a problem, as they will light dimly from a tiny current, sometimes just the leakage from a switch and wiring can make them glow.
Google some schematics for lamp dimmers to get an idea, if your switching leds then you might have to pull a neutral wire in.

 

[bsculley]

Hi, and thanks for the reply. I took your advice and found lots of circuit diagrams, but none I completely understood. It's hard for me to separate the power supply from everything else. I did find an actual X10 schematic that I think included the power supply, but there were no device numbers or component values.

I'm not expert on this stuff, so I was kind of hoping for a "cookbook" solution.

 

[Nigel Goodwin]

Really you need to run a neutral - particularly with LED's, and you shouldn't really be using anything else.

 

[bsculley]

Thanks, but I'm not using LEDs and I'm not planning to rewire the house either. I just want to replace the X10 module with an ESP-8266 wireless module.

It would be great if somebody could reverse engineer the X10 power supply.