[stevep]

Anyone out there know if the basic LED GU10's are dimmable using normal theatrical dimmers? (Strand Act6+ to be precise).

The light output from a bog standard B&Q GU10 in a birdie is sufficient for the effect needed - but I'm wary about knackering them really quickly (or the dimmer for that matter)

If the answer is no - or not advisable then if anyone knows of dimmable ones available from CPC etc then would appreciate a point in the right direction.

Ta




(tried searching the forum but plenty discussion found about light output etc just couldn't find anything about dimming them)

[adam2]

In general, no the cheap LED GU10 lamps cant be dimmed.
Although the instruction not to dim them refers primarily to d0m3stic dimmers, it must be remembered that theatre dimmers work on similar principles.

Dimmable LED GU10s certainly exist but are more expensive and less widely available.

[hadyn.williams]

adam2, on 02 February 2012 - 04:06 PM, said:

Although the instruction not to dim them refers primarily to d0m3stic dimmers, it must be remembered that theatre dimmers work on similar principles.

Sorry Adam, but I beg to differ. I believe d0m3stic dimmers work by varying resistance. Most theatrical dimmers work by chopping the wave form. Unless of course I've miss-understood what you mean by 'similar principles'

[boswell]

d0m3stic dimmers work by chopping the waveform, usually by delaying the switch on by a varying amount from the zero cross over point. very simple circuit.
B&Q/CPC GU10 LED's do not dim with d0m3stic dimmers, they stay lit all the way down to almost off then just go out, even with a high wattage ballast load in circuit as well

[hadyn.williams]

boswell, on 02 February 2012 - 04:36 PM, said:

d0m3stic dimmers work by chopping the waveform, usually by delaying the switch on by a varying amount from the zero cross over point. very simple circuit.

In which case I apologise to Adam. Guess the last one I took apart was an old one, but it just had a little variable resistor buried in it. I presumed the cheapo ones still did it the same Old Skool way.

This post has been edited by hadyn.williams: 02 February 2012 - 04:55 PM

[Simon Lewis]

hadyn.williams, on 02 February 2012 - 04:37 PM, said:

In which case I apologise to Adam. Guess the last one I took apart was an old one, but it just had a little variable resistor buried in it.

erm... yes - because you need to vary the resitance in part of the circuit to change the point in the mains waveform at which the device switches on! One of the main difference between domestic and theatrical dimmers is the degree of supression that is applied.

This post has been edited by Simon Lewis: 02 February 2012 - 04:57 PM

[timsabre]

Even the dimmable ones don't dim very well - they go down to about 30% or 40% then snap off.

Also they usually flicker on domestic dimmers because they don't present a big enough load. A theatrical dimmer such as the Act 6 would not have this problem though.

[Oovis]

timsabre, on 02 February 2012 - 06:02 PM, said:

Even the dimmable ones don't dim very well - they go down to about 30% or 40% then snap off.

Also they usually flicker on domestic dimmers because they don't present a big enough load. A theatrical dimmer such as the Act 6 would not have this problem though.

The Act6 data sheet says it requires a minimum load of 100W so an LED GU10 still wouldn't dim on its own without loading up..

[alistermorton]

hadyn.williams, on 02 February 2012 - 04:37 PM, said:

In which case I apologise to Adam. Guess the last one I took apart was an old one, but it just had a little variable resistor buried in it. I presumed the cheapo ones still did it the same Old Skool way.

If you'd looked a little closer you'd have also found a little choke and a triac in there along with a couple of resistors and capacitors and probably a diode transistor zero crossing detector. Theatrical dimmers use their big brothers. The triacs on d0m3st1c dimmers get killed regular as you like when the lamp blows because they aren't protected very well. I've got some that are either full on or (may commonly) full "off" (dead).

This post has been edited by alistermorton: 02 February 2012 - 08:36 PM

[Don Allen]

The thing to remember with dimmable leds is that they power themselves from the chopped ac output from the dimmer and sample the dimmed waveform to determine what precentage the led needs to be dimmed to. Therefore they cannot dim to zero as they do not have enough supply to operate at very low levels.

At his time for a fully dimmable led, you need a DMX controlled led driver supply.

LED's magazine dimmable leds

[dwright2104]

I got 6 GU10 Led's from CPC when they were on special I think they were a £1 each at the time, I got them for the lights in the toilet and utility room (no dimmers) as the bulbs were blowing so often.

Just out of curiosity I tried 6 of them in the Kitchen (has total of 12 so 6 were still halogens) which has a standard domestic dimmer, and they dimmed very sporadically, None of them were at the same brightness at any point except full on or off. the dimming curve was very squareish as apposed to a nice curve. but they did dim to about 15%, but then again there was still 6 x 35watt halogens on the circuit swell.
Needless to say still have the halogens in the kitchen. the Dimmer seems to make a big difference to bulb life if turned up as apposed to just switched on.

This post has been edited by dwright2104: 03 February 2012 - 12:58 AM

[boswell]

Don Allen, on 03 February 2012 - 12:00 AM, said:

LED's magazine dimmable leds

2 years on and we are still waiting for it to hit the market!!

This post has been edited by boswell: 03 February 2012 - 08:28 AM

[Nic Forsdike]

I have used the Philips Masters GU10 7W LEDS on a selection of dimmers and they seems to work well, very expensive to purchase. We have installed them our cafe, foh and as auditorium house lights running on Mode Dimmer and ETC sensors

My advice dont buy cheep LEDS it false economy

[timsabre]

Nic Forsdike, on 03 February 2012 - 07:19 PM, said:

I have used the Philips Masters GU10 7W LEDS on a selection of dimmers and they seems to work well, very expensive to purchase. We have installed them our cafe, foh and as auditorium house lights running on Mode Dimmer and ETC sensors

My advice dont buy cheep LEDS it false economy

Just out of interest, how long have they been in and how reliable have they been?

[Nic Forsdike]

nearly 3 years and not 1 has ever failed and I have installed over 75 unit and still installing them