Convert LD90 from Dimmer to Hot Power

[adamharman]

Interesting, I wouldn't be worried about connecting any sort of load to that.

Would it be possible to add a small capacitor somewhere to smooth out the drive signal completely?

 

That mains waveform is attrocious. Are you sure it isn't a limitation of your scope....

[DrV]

Interesting, I wouldn't be worried about connecting any sort of load to that.

Would it be possible to add a small capacitor somewhere to smooth out the drive signal completely?

 

That mains waveform is attrocious. Are you sure it isn't a limitation of your scope....

There's nothing wrong with the drive signal. It's just the way I probed it. The drive comes from a uln2003 which then drives the opto through a 1k5 resistor. The opto is supplied by a fairly rough 16V supply on the anode. I probed the cathode of the opto because it's easy to get at (on the ribbon cable). So what you see is a 2V signal on top of 16V with a bit of ripple. I a.c. coupled it so I could turn the scope sensitivity up and still have the label next to the trace.

The mains really is like that. The voltage is terrible too - about 215 right now but I've seen it less than 200 on a winter evening!

[timsabre]

One of the other problems with some dimmers set to switch mode is current leakage when "off" through the suppression components which can be enough to intermittently power up intelligent fixtures (eg led pars). So you get a repeating flash. Does LD90 get round this?

[DrV]

One of the other problems with some dimmers set to switch mode is current leakage when "off" through the suppression components which can be enough to intermittently power up intelligent fixtures (eg led pars). So you get a repeating flash. Does LD90 get round this?

You're right of course. I hadn't considered that. I don't think it does get round it. I seem to recall seeing a spark when putting a test lamp on with a dirty probe. Can't check now as I've packed it all away but I'll have a look when I can.