Trailing edge dimming for LED GU10

Discussion in 'C-Bus Wired Hardware' started by tobex, Oct 24, 2010.

  1. tobex

    tobex

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    At this moment I am led to believe that

    "1 x 9W (3*3W) CREE LED Dimmable GU10 Downlight Globe 240V AC"

    Is one of only a few such products on the market today which are;
    - GU10 240V
    - Dimmable
    - LED illumination
    - 60degree
    - White 6000K

    I have been installing GU10 for years and now I see the prospect of using LED replacements. The supplier specifically notes that TRAILING EDGE dimming is necessary and I was wondering if

    Version 1: Black boxes with 4 channels dimming
    Version 2: 8 Channel x 1A

    were compatible with trailing edge dimming.

    I want to make sure that I am not jumping the gun with an early product only to find that I made a $30 per socket mistake.

    Most sellers are not even aware that many 12V LED products CAN NOT BE DIMMED at all. Then others are offering part numbers of various products e.g. Lutron LED dimmers.

    As far as I can tell the only difference between a normal power source for a 12V halogen downlight and a dimmable power source for a downlight is about $3 in LED driver chips and some capacitors. However, for reasons only known to market forces the industry has launched both the 12V versions and the 240V versions with no adequate explanation or how to use the equipment or where to buy power supplies.

    I anticipate that the arrival of adequate power sources will dramatically accelerate the uptake of LED lamps. For now the only self-contained solution is the GU10 dimmable variant.

    Be warned that GU10 is the lowest cost per socket installation. It has no additional power supply requirements and while you can purchase a 12V replacement lamp in LED design for $15 you are up for another $30-$80 for a driver that will respond to dimming requests correctly.

    If your clients are chomping at the bit to install LED. They will want GU10 fittings for now.
     
    Last edited by a moderator: Oct 24, 2010
    tobex, Oct 24, 2010
    #1
  2. tobex

    Don

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    If you search these forums, you will find reference to several other 240V dimmable LED lamps. I have tested a few, and know that there are others which will work. Most of the lamp + driver combinations I have tested work well with trailing edge dimming (and universal dimming).

    The biggest problem you will find is related to the low power of the lamps. A 9W lamp does not draw enough current to keep most dimmers operating normally. If you are connecting to multiple lamps from one dimmer, you are likely to have better luck. Some manufacturers specify a minimum number of lamps that are required to work with specific dimmers, and if you follow their guidelines, LEDs can be driven successfully from both universal and leading edge C-Bus dimmers.
     
    Don, Oct 24, 2010
    #2
  3. tobex

    Newman

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    I assume the question you're asking here is which type of dimming do the C-Bus 5104D750 (black box) and C-Bus 5508D1A (8 x 1A) series dimmers use? If so, then the answer to both questions is Leading Edge. If you need a Trailing Edge C-Bus dimmer then you need a L5504D2U DIN Univeral Dimmer or an Architectural Dimmer. To meet the minimum load requirement you'll probably need at least two of these bulbs in parallel on a dimmer channel, maybe more.

    I'm not sure exactly which TE dimmable GU10's you're referring to but if they're anything like the trailing edge dimmable GU10's from LEDCentral be prepared to be disappointed. To my uncalibrated eyes they looked about 250 lumens (less than 1/3 when compared to a 50W halogen) and the minimum brightness was very high. A 12V version is available and the brightness between the 12V and 240V versions seems to be the same. Despite being rated as 9W I found them to only be drawing just under 5W, which would correspond with the lowish lumen output. When I aksed LEDCentral about this they just said that they only used a little over 5W but they sold them as 3 x 3W because that's how all their competitors sold their equivalent bulbs, i.e. they all lie.

    I doubt that the GU10 form factor will have a drop-in equivalent in the near future because the heat dissipation requirements of LEDs will always be an issue and further dissipation is introduced in the driver circuitry that is necessary to keep the dimmer working.

    The MR16 form factor has the same issues, but the difference is that because the driver is external, the dissipation required to keep the dimmer running is separated from the lamp itself, meaning the LEDs can be driven harder for the same thermal performance. The other advantage of MR16's is that they are usually designed to run from a varying voltage, so if the electronic transformer could successfully dim a halogen, there's a good chance it will be able to dim a few MR16 LEDs in parallel (subject to minimum load), as the dimmable MR16's I've come across all have internal current regulation.

    There are a number of direct dimmable equivalents to halogen downlights available at the moment, (Pierlite Starburst, Crompton XL, Alphalux, Brightgreen) but they all come at a hefty price. If you want it to just work, be prepared to pay for it.
     
    Last edited by a moderator: Oct 24, 2010
    Newman, Oct 24, 2010
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  4. tobex

    tobex

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    Some sellers were quoting Lutron part numbers to drive MR16. For now at least it looks like a nonsense proposition. If they can't speak on level terms with what customers need then it makes no sense to run our and buy the stuff.
     
    tobex, Oct 25, 2010
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  5. tobex

    Newman

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    The nicest of the lot seems to be the Pierlite Starburst / Crompton XL units as they work with any dimmer, LE or TE and can be retro-fitted into any MR16 fitting that has sufficient space behind it to accommodate the extra length of the lamp. I think the only time that you even need to think when using these things is that you need 2 units in parallel on a Clipsal stand-alone leading-edge dimmer to meet the minimum load requirement.
     
    Newman, Oct 25, 2010
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  6. tobex

    tobex

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    I am waiting for the 0.1A 32 Channel dimmer module to come out. :rolleyes:
     
    tobex, Oct 25, 2010
    #6
  7. tobex

    Duffman

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    Dimmable LED Problem

    Hi All,
    I have cobbled together a c-bus design using knowledge I have gained from this site as well as trawling the internet for other examples. I designed the system to use a combination of CFL and LED technology (relay / dimmable modules) in an effort to keep costs down and also future proof the design. Having read some later updates it seems I had some flawed thinking. Basically, I assumed that the Chinese dimmable LED technology was a plausible way to go. Error!

    I am trying to salvage my design, but it largely relies on the cheap Chinese LEDs that throw a reduced amount of light. I have many fittings to compensate for this (ie: 9 LED fittings instead of 1 incandescent equivalent). I made a test rig to see what sort of light is generated and was happy with the result. Anyway, the physical layout required to utilise these LEDs is not really compatible with any other design approach. Similarly, placing a single PierLite Starburst fitting in place of an array of LEDs isn't a solution either.

    My question is does anyone have a good design approach to the problem of balancing achieving immediate lighting requirements whilst allowing for future upgrade to dimmable technology? Also, as tobex mentioned, is 0.1A 32 Channel dimmer module really being released and would this be dedicated to LED lighting solutions?

    Thanks for your help. This forum always expands my understanding of cbus.:p
     
    Duffman, Jan 21, 2011
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  8. tobex

    tobex

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    It appears to me that the solution can be salvaged with a LED ballast operating on a single channel per ballast. The ballast so made that it will support the requirements of the job you have designed.

    As far as I know you will either lose your hair or you will lose your savings. There is today nothing in the market which is both approved and also at the same time cheap.

    The production systems (aka China) have not yet addressed the problem of handling groups of LED fittings as a 240V problem in a way that is logical to electricians and also C-Bus.

    C_BUS ======== BALLAST ===== Lamp 1 ... Lamp 2 ... Lamp 3 ... Lamp N.

    It is plausible and possible to easily design and build a drive to achieve this result. I note that a number of GU10 fittings claim to have this ballast internally and the replacement for 12V downlights claim to have a viable replacement driver for LED externally. Thus far Lutron claims to have a powerful ballast and Lutron needs to be spelled so Lu$$$(ouch)$$$tron.

    However, on a mass scale, such as a room with 20, 30, 40 lamps it is not clear what to do. We are defeated by heat, output and price.

    To date I have only ever seen this concept developed on a long PCB and installed under a tread outdoors. I spoke 10 years ago to Howard Showers who felt they held the keys to global domination with this concept.

    These driver chips and the transistors which protect them are nothing more than cleverly made voltage regulators with a specific operating bandwidth which makes them suitable.

    There is no 32 channel dimmer. That is my failed attempt at humour.
     
    tobex, Jan 24, 2011
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  9. tobex

    Duffman

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    Led Drivers

    HI,
    Thanks for the reply. I had a feeling the 32Ch module was a fake! The guy at Clipsal that I was talking to thought it was an awesome idea. :rolleyes:

    I'm sure I once saw a Dynalite multi-channel LED Driver at some point. Before Philips bought them out. On this point, why not provide a module to directly drive leds (not LED replacements)? What is the technical obstacle here? :confused:

    Cheers.
     
    Duffman, Jan 31, 2011
    #9
  10. tobex

    Ben Hill

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    Hi, I am using a dimmable GU10 8.5 watt that is 3000K 450 lm.
    I brought them from a local guy in Cairns Dave from Oz led works.
    They work great with Clipsal dimmers no problem at all and they were only $28.00 each, check their web site www.ozledwork.com or give him a call 0412 213 885, tell him Ben sent you because he normally charges $35.00.
    I have tried so many LED lights all rubbish, these really do work.
    I had two channels doing 8 halogen lights, we made them dim together, I now have all 8 on one channel, no problem, it even worked with just one globe and I was told I could have 13 on one channel.
    Must say I'm blown away how many people selling rubbish, Dave told me his globes were made to work with C-bus.
    Hope this is of help, I have told so many people who have all tried them with great results.
     
    Ben Hill, Feb 16, 2012
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  11. tobex

    tobex

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    This sounds like an advertisement.
     
    tobex, Feb 17, 2012
    #11
  12. tobex

    ashleigh Moderator

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    Yes, does a bit, especially with a number of posts about the same thing, only a few minutes apart.

    Any more blatant plugging might see a short ban :)
     
    ashleigh, Feb 17, 2012
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  13. tobex

    l60mcm

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    Has anyone else used these LEDs and know how successful they are I am Keen to get a solution that work with the leading edge dimmer. But as I am from the uk I would like some feedback before ordering (even a sample)
     
    l60mcm, Feb 17, 2012
    #13
  14. tobex

    DarylMc

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    Hello Newman
    I have 6 starburst fittings which I have been evaluating in my office.
    There are 4 channels used just because that is how it was wired before.
    2 x 2 led per channel and 2 x 1 led per channel.
    I'm very happy with them.
    From the data sheet I gathered it is OK to use from 1-6 fittings per channel on the L5508D1A leading edge dimmer.
    http://www.pierlite.com/download.ph...immer+systems+effective+June+2011+issue+2.pdf
    Have you had some other experience?
     
    DarylMc, Feb 17, 2012
    #14
  15. tobex

    Newman

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    1 - 6 fittings is the stated range for the Starburst on the C-Bus Leading Edge DIN Dimmers. Stick with that and you'll be fine. Any more than that exceeds the maximum allowable capacitance rating for the dimmer channels as stated by Clipsal.
     
    Newman, Feb 20, 2012
    #15
  16. tobex

    Ben Hill

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    Sorry Ashleigh for plugging the guy, my mistake it won't happen again.
    I did not think I was doing anything wrong.
    I see so many people advising products, that's why I thought it was a good idea.
    :eek:
     
    Ben Hill, Feb 24, 2012
    #16
  17. tobex

    znelbok

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    I for one appreciated the plug. Made contact and will be trying out one.

    I did not notice that he posted a few about the same guy and if that was the case then yes there is thin ice involved, but a single plug can be very helpful.

    Mick
     
    znelbok, Feb 27, 2012
    #17
  18. tobex

    travis1973

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    LED GU10 Lights flashing when turned off

    Hi,

    I recently purchased some GU10 bulbs to replace the halogen ... no issue on one dimming circuit but on another dimming circuit when the lights are turned off the lights flash..

    Is there a setting causing this or do you think there are other issues..

    Thanks,

    Travis...
     
    travis1973, Aug 23, 2013
    #18
  19. tobex

    DarylMc

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    Hi Travis1973

    I suspect the lights on the dimmer channel which are not flashing may have more lamps and therefore more load per dimming channel.
    Is that the case?
     
    DarylMc, Aug 24, 2013
    #19
  20. tobex

    travis1973

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    Yes the flashing ones there are only two lights on the circuit where there is 6 on the other circuit..

    Is there a remedy for this ... I have overcome it for now by having one halogen in there and one led ... but would prefer to have all led in the long run...

    Cheers,
     
    travis1973, Aug 24, 2013
    #20
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