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Halogen to LED

Discussion in 'LEDs and Optoelectronics' started by Tony1958, Sep 8, 2018.

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  1. Tony1958

    Tony1958

    2
    0
    Mar 22, 2014
    I have 16 50W halogen lamps in my kitchen ceiling. The lamps are 12 volts with 5.3 bases. Whoever installed them buried the transforme in the ceiling and wired it back to a switch on the wall. I have no idea where the transformer is or where the wiring is running.

    When I replace the lamps with led lamps they start to flicker. This is not surprising as I guess the 12 volt output from the transformer is not very regulated. Obviously this is fine for the halogens but not the leds. The answer of course is to replace the transformer with an led driver transformer that will give 12 volts regulated output. However I cannot do this as I have no idea where the transformer or the wiring is and short of ripping down the whole ceiling have no idea how to find it.

    I guess all the fittings are wired in parallel. Does anyone have any ideas how I might sort this problem by adding something in parallel with the 12 volt supply in the ceiling void. The only thing that I can think of is to wire a 10,000 microfarad capacitor across the 12 volt supply and see if this provides enough smoothing. I am not sure I am that happy with a large capacity capacitor in the ceiling void, or whether this is even large enough to provide sufficient smoothing. Has anyone got an better ideas???

    Cheers

    Tony
     
  2. Bluejets

    Bluejets

    5,524
    1,163
    Oct 5, 2014
    Actually not regulated at all, if the old black wound transformer type,
    it is simple ac output.

    There are LED driver modules suitable that will plug in to the existing lamp socket and drive a variety of different led types and sizes.

    Example here............. https://www.ebay.com.au/itm/DC-12V-...316560&hash=item4ad9492b21:g:MkIAAOSw9W5bYfnd

    Failing that there are LED driver units BUT you must use the type suitable for the lamp you have if it is MR16 type LED and you'll have to "dig out " the old transformer.
    Actually, most I ever had anything to do with were within about 200mm of the light as that was only how long the low voltage lead was.

    Then again, you may have the electronic drivers for the old lamps and they definitely will not work with anything but as I said before, leads are usually rather short secondary and a tug on the lead usually drags the driver out the hole in the ceiling.
     
    Last edited: Sep 8, 2018
  3. Alec_t

    Alec_t

    3,137
    852
    Jul 7, 2015
    Sounds more like an operating theatre than a kitchen :). Are you planning to have the same level of LED lighting, or will you be lowering the wattage somewhat?
    If the lamps are indeed all in parallel, then presumably there is a 16-way distribution block somehere, in addition to the chunky 800W transformer. Those surely would have required installation access through the floor above the kitchen ceiling. Have you checked for evidence of a hatch, or lifted flooring, in the room/loft over the kitchen?
     
  4. HellasTechn

    HellasTechn

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    215
    Apr 14, 2013
    Yes... The hallogen bulbs work with AC. It makes sense and explains the flickerig because the LED is a diode after all.

    I would just ignore the old transformer and wiring and install a led PSU with new wiring. The LED lamps will go in parallel with each other and the psu.
     
  5. Externet

    Externet

    809
    182
    Aug 24, 2009
    A single? 800+ Watt transformer should be massive enough to find it with a metal detector. (Like one in a μwave size)
    Borrow one and have fun sweeping ceiling (and walls?) if there is no ceiling/attic? access.
    When found, you also find the mains primary source for all lamps, and the 12V secondary distribution wiring...
    Depending on the 12V wiring installed, the lamps can be replaced with 120V LED bulbs fed directly, and a free paperweight for any other project.
    By electrical building code, the transformer and wiring splices should be accessible by a box cover. Try determining the direction wires come from by exposing ceiling sockets.
     
    Last edited: Sep 8, 2018
  6. Bluejets

    Bluejets

    5,524
    1,163
    Oct 5, 2014
    Each fitting will have it's own driver/transformer driven by mains on the input.
    Op probably means the lights all come on together.
    That misconception certainly took the train in the wrong direction......o_O
     
  7. Bluejets

    Bluejets

    5,524
    1,163
    Oct 5, 2014
    No, the halogen lamps are more than likely supplied by a driver which some refer to as an electronic transformer.
    The ones that come with the halogen lamp will not be suitable for the LED lamp for obvious reasons and they flicker like crazy at the "under minimal designed loading"'.

    As I said before, the driver/transformer should be a short distance from the lamp(<200 mm).
    Long leads on the secondary will make the lamp go dim or never come on due to the high frequency AND the capacitive reactance that causes in the secondary wiring.
    Found that out 20 years ago when these things first came in.
     
    HellasTechn likes this.
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