long shot – faffing with LED replacements bulbs, drivers and dimmers

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  • long shot – faffing with LED replacements bulbs, drivers and dimmers
  • Right – could do with some help if you’re a sparky with LED lighting experience and expertise

    I have 12 , yes 12 X 50 W halogens (MR6) in my kitchen. That’s 600W of heat plus a bit of light 😀

    It’s a dimmable circuit too – looks like a standard (triac?) dimmer switch (I can see a coil in there plus a bit of electronics)

    They are driven at 12V DC in pairs from Aurora 35-105W drivers.

    I have bitten the bullet and got some dimmable Philips 7W LEDs (meant to be excellent at working with a variety of drivers) – tried one and it worked just fine (and dimmed ok) so ordered 12.

    Since fitting (retaining the existing drivers) them I have had a variety of issues – some flashing bulbs (which I’m guessing is a results of not enough load on the driver), one driver looks like its gone pop completely. Currently have a mixture of new LEDs and the old halogens.

    Recently got some constant current LED drivers which didn’t work on one LED bulb so stopped it quickly- but I’m getting out of my depth to what will make these work!

    So -questions

    1. Do I need to change the dimmer switch? (I’ve seen there are clever LED friendly ones that don’t chop up the current which to my understanding is how dimmers work and probably not what LEDs and LED drivers like..)

    2. do I just need a specific dimmable LED driver? I’ve seen these about but tricky to find..

    3. any other hints or tips?

    Thanks

    TM

    Premier Icon Flaperon
    Subscriber

    Most LED drivers require trailing edge dimming, which your triac dimmer switch can’t do. Varilight do a decent range of cheap digital dimmers.

    Are you absolutely sure your new drivers are dimmable? Should say on them which type of dimming to use.

    Berm Bandit
    Member

    You covered it in your post.

    You’ve got a dimmer designed to vary the current. LED’s are very susceptible to current fluctuation, again as you’ve mentioned (constant current drivers), so the fact is that when you add the two things together you’ve got a recipe for problems, especially when you have such low loads. (i.e. a 1 watt variation on a load of 50W is 2%, on 7W its 14.28%, so not surprisingly it has a different impact)

    The development of LED lighting has been rapid. Until recently it was to provide a light source similar in output to Halogen that didn’t make you look like you were on a mortuary slab. Right now its for a dimmable solution. I import a range of high quality LED downlights purported to be dimmable, we choose not to advertise that as a feature. Experience shows that even in ideal conditions all sorts of anomolies occur as you describe. We have hunted high and low for a suitable dimmer, and to date have not found one that works in all conditions.

    Personally I wouldn’t go anywhere near an LED replacement lamp, unless they are a top brand, as the power supply issues are just too likely to cause you problems. My inbox is full of offers of these things from every two bit factory in the Far East, and I guarantee one thing, and that is that 99% will be utter crap.

    Thanks folks

    I think what I need is

    1. dimmable high quality LED lamps
    Got Philips dimmable 7W bulbs – tick

    2. Dimmable LED drivers (with stated leading/trailing edge control)
    Not found these yet (the ones I have do not state they are dimmable – bought them on a guess and can return these) -the search goes on!

    3. a digital dimmer switch (240V) for the wall, leading/trailing edge to match the drivers.
    Will search for this when drivers located.

    Any advance on this as a plan? any recommendations for item 2 (dimmable drivers)?

    Thanks
    TM

    Premier Icon molgrips
    Subscriber

    Sorry for the hijack:

    My cooker hood has 2x25W halogen G4s. I’m tempted to buy LED G4s and install a driver transformer inside the hood itself.

    Am I insane?

    Premier Icon Flaperon
    Subscriber

    twiglet – Philips do a range of dimmable LED drivers but as Berm Bandit says none of them are perfect.

    The Philips ones will dim a load from 0 to 50W and work fairly well, but have a high capacitance leading to potential issues with soft start dimmers. They flicker slightly at the very lowest setting, but I’d say they dim properly from 5% output and higher.

    Premier Icon nixie
    Subscriber

    Molgrips,

    Yes, you don’t need the driver. Suspect the current bulbs are mains voltage so just replace with mains voltage led bulbs. Works great in my cooker hood.

    Premier Icon ampthill
    Subscriber

    Berm Bandit

    wish I’d seen you post earlier as I’ve just ordered 6 replacement G9s

    Are these going to suck?

    http://www.energybulbs.co.uk/kosnic+4w+g9+led+capsule+-+warm+white/1813415572

    I have 14 days to return them

    Do you sell retail?

    Premier Icon Flaperon
    Subscriber

    Kosnic are pretty good, though that particular bulb seems a bit overpriced.

    Premier Icon molgrips
    Subscriber

    Yes, you don’t need the driver.

    Hmm.. the bulbs I saw said that you needed a steady enough power supply otherwise they’d die.

    What brand did you get? Got a link perhaps?

    oldgit
    Member

    twiglet, those Aurora 35-105W are transformers not drivers. They are dimmable with a standard dimmer.

    I also assume the LED’s you have are MR16 retro fit LED’s?

    You have two weak links, one is the transformer, they’re consumable and prone to fluctuation and interference.
    And secondly the ceramic lampholders can break up and cause flickering. Quite often it’s the lampholder that’s gone, and the user thinks it’s either the lamp or transformer.

    I never like to recommend retro fit LED’s on LV systems, and dimming is double trouble. LED’s really don’t like it.
    What I do is remove the transformer. Then replace the LV lampholders with 240V GU10 lampholders.
    If they still want dimming, I fit dimmable LED’s and retro fit a trimmable dimming module into their existing dimmer.

    I don’t really like dimming, instead I prefer switched banks of varying outputs.

    Berm Bandit
    Member

    I think the key issue in this thread is MR16, i.e. low voltage as opposed to GU10 mains voltage. The GU10 stuff is much more stable for the reason oldgit has stated. Basically the lamp has a driver built in, so all those issues are covered straight off. I’d still steer well clear of dimming personally, but thats a personal call.

    So thats the answer to the questions about G4’s and G9’s in my opinion. Regarding selling to the public, its a case of the worn out turks head …….. we’re a distibutor to the trade, and its a problem for me to do that, but all the advice above, which is pretty much on the money all the way through the thread should see you right.

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    (A Frayed Knot 8) )

    Premier Icon nixie
    Subscriber

    What brand did you get? Got a link perhaps?

    Lidl own brand ones in the cooker hood so nothing special.

    zafer
    Member

    @twilight_monster, it’s not uncommon for hobbyists to find themselves in a situation where we can have a lamp in kitchen which takes 600W. Now 600W is actually a lot of power to be spent on a lamp. I think 7W Philips LEDs would be the accurate fit for your issue. I bought them recently and I’m really happy with their power saving as well as the colour which is not too bright that it irritates your eyes and not too dull that it looks yellow. The brightness of these lights is just about the right quantity.

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