Remote Mains PWM

[ronsimpson]

The controller and lights are plugged into different mains sockets but all in the same room of the house. Is it possible that the sinewave is offset at the different sockets?

Likely there are two different phased in the same room. They should be 180 out. I thought 180 off will not upset a triac.

[The Master]

When you say "180" do you mean 180 degrees offset? That would normally be fine as the controller has 2 diodes and looks at the DC ripple and the triacs operate in AC anyway.

By the way, all sockets in this room are on the same ringmain. The only difference is the length of wire between each socket and the consumer box

[ardhuru]

One issue I can see; if you are detecting the zero crossing referenced from the transfomer secondary, there is likely to be a slight phase difference.

Also, is the objective of the circuit to adjust the intensity? If that is the case, why use PWM? That is likely cause a lot of trouble, and unlikely to work. All you need is a fixed pulse (say 200 uS); depending on how much after the zero crossing the pulse is given, the triac will control the bulb's intensity.

Regards,

Anand Dhuru

[The Master]

The phase difference from the transformer shouldnt cause a problem. Ive made circuits like these before but usually the circuit and the bulbs are powered using a single wire.

The purpose of the PWM is so i can adjust the brightness of the lights from a PC

[HenrikOlsson]

Hi,

They should be 180 out. I thought 180 off will not upset a triac.

I'm pretty sure there are three phases, shifted 120°, 230VAC between each phase and neutral and 400VAC from phase to phase in the UK. (At least that is what we have here) But please do correct me if I'm wrong!

Anyway, if the outlet providing the reference (zero crossing) and the outlet actually providing the current to the load is not on the same phase it won't work properly because they are not "in phase" - obvioulsy.

Can't you just, as a test, power the load from the same outlet as the control circuit just to see if it works or not.

/Henrik.

[The Master]

I believe that is correct for 3-phase supplies. Our house runs on a single phase (only 2 wires into the entire house). All sockets are connected together on a ringmain.