Jamtastic3 Posted November 23, 2013 Share Posted November 23, 2013 Hi BR. So the spark at the venue I work in is having a problem with what is supposed to be a circuit of 30 x 5w dimmable LED GU10's. He's installed a 'special' dimmer dial (it looks like a normal household dimmer but I'm guessing a lower rated dimmer for the LED's) but still the GU10's aren't dimming. What does happen though is that as the dimmer is decreased from 90% to 50% there's a crazy amount of strobing from the GU10's. Then down to 20% they just switch off. Like I said, these GU10's are dimmable but I'm wondering if there's something we're missing here. Any advice? Surely a normal lighting circuit can take dimmable LED's (with the right wattage of dimmer dial)? Unfortunately I don't have any other details such as the wattage of the dimmer. Link to comment Share on other sites More sharing options...
topsy100 Posted November 23, 2013 Share Posted November 23, 2013 you need to make sure that the dimmer is correct for dimming LED its a long story about dimming curves of LED that is very boring Link to comment Share on other sites More sharing options...
bigclive Posted November 23, 2013 Share Posted November 23, 2013 Something worth trying is to add a resistive load on the circuit. Perhaps a few tungsten GU10's? It might be that the dimmer is struggling to latch with the load being lots of little switchmode power supplies drawing their current as irregular pulses. If that doesn't work then you may have to question whether the dimmable GU10's are actually dimmable after all. I've seen some cheap ones that clearly use the standard circuitry being presented as dimmable when they aren't. Sometimes salespeople throw in buzzwords to sell stuff without really knowing what they're saying. Link to comment Share on other sites More sharing options...
timsabre Posted November 23, 2013 Share Posted November 23, 2013 Definitely add some normal lamps as resistive load as Clive says. But also trailing-edge dimmers work better with dimmable LEDs - this may be what the "special" dimmer is. Link to comment Share on other sites More sharing options...
rossmck Posted November 23, 2013 Share Posted November 23, 2013 What type of LEDs are they ? I've found that the latest Osram / Philips / Soraa ones dim pretty well, but a lot of the budget ones do not. Also found that in many cases the 12v GU5.3 MR16 versions seem to dim better than the 230V GU10s. Usual full disclosure applies - I am associated with a company that sells these (well, Osram and Soraa anyway) - but the above comment is from my own experience :) Link to comment Share on other sites More sharing options...
ImagineerTom Posted November 23, 2013 Share Posted November 23, 2013 That strobing is textbook response from LED's that don't like the power supply they're being fed with (we experience it a lot when people try to power our units off cheap inverters or step up/step down'd power supplies that chop around with sine waves. Stick an inductive load and your LED's on a "known good" dimmer and make sure they are happy being dimmed then start looking for a new dimmer for 'em. Link to comment Share on other sites More sharing options...
musht Posted November 24, 2013 Share Posted November 24, 2013 Think Tom meant resistive load, dinnae put an inductive load on a trailing edge/reverse phase control dimmer it wont like it. Link to comment Share on other sites More sharing options...
ImagineerTom Posted November 24, 2013 Share Posted November 24, 2013 Ahh yes you spotted my, erm, deliberate mistake there.... :-p Link to comment Share on other sites More sharing options...
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