Dimmer for Flourescent Lamps

Discussion in 'General Electronics Chat' started by boatsman, Jan 30, 2010.

  1. boatsman

    Thread Starter Senior Member

    Jan 17, 2008
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    390
    I need to be able to dim two banks of 40 W fluorescent lamps-total eight lamps. My mains supply is 220 VAC at 50 Hz. Can anyone please supply me with a circuit I can build on Veroboard, bearing in mind that I have no access to test equipment other than a digital multimeter?
     
  2. VoodooMojo

    Active Member

    Nov 28, 2009
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    Last edited: Jan 30, 2010
  3. awright

    Well-Known Member

    Jul 5, 2006
    84
    7
    Despite the citation of excellent and interesting information by VoodooMojo, I believe the appropriate answer to boatsman's request is that conventional fluorescent lamps in conventional fluorescent fixtures are not dimmable by means accessible to one having, "...no access to test equipment..."

    The IR data cited is intended for engineers developing new products, not hobbyists. While it is certainly possible for an advanced hobbyist to go through the design procedures presented in the cited material and other app notes out there, I think it is a disservice to boatsman to give him the impression that it is just a matter of reading an app-note and putting a few components on a perf-board.

    I get the impression (perhaps erroneously) that boatsman was hoping to be presented with a schematic of something of the approximate complexity of an incandescent lamp dimmer (which is quite a practical project for a hobbiest). That is simply not possible.

    If boatsman will provide us with a little more detail on what he is trying to accomplish, perhaps we can suggest a more practical strategy, such as simply switching off some of the lamps if it is a large room illumination task or purchasing dimmable compact fluorescent bulbs and fluorescent-compatible dimmers if it is a small room situation.

    awright
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    I'll respectfully disagree with one point, a DVM is all that is needed if you have a working diagram. A DVM in the hands of a trained tech is good for the vast majority of jobs you might encounter.

    Having said that, I'd also have trouble translating the PDF into a working dimmer.

    A quick search on Google shows they are out there, in quantity. This may be a case where it is better to buy than to build.
     
    Last edited: Jan 31, 2010
  5. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    thanks awright for solidifying my train of thought.
    I was making a point that there is not a simple solution to
    fluorescent light dimming.
    We see all the time people looking for easy fixes for complex
    problems. Many of them turn out be just darn dangerous.

    I posted the pdf to exhibit that simply adding a
    potentiometer and some other components on a breadboard and
    hooking them to mains powered, ballast boosted tube fixtures
    is not a wise decision nor is it an easy task to dim a fluorescent tube..
     
    Last edited: Jan 31, 2010
  6. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    Been there, tried that from several different approaches, most are dangerous to a fault. Components overheat, tar melts, smoke billows and stinks to high heaven, and eventually sparks fly.:eek:

    Mr. Marsden is spot-on.............buy it. At least then you have someone elses' liability insurance to fall back on :D
     
  7. doctor1

    New Member

    Jan 28, 2010
    2
    0
    Dimmers up to a 1000 watts you can buy at your local electricial supply.
     
  8. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    Thanks Doc!
    Do you know the make and model number of a good one?
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,176
    397
    Philips # DIM-140H-TP , 120V, 5%-100%. Try Philips General Support 1-888-744-5477
     
  10. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    DIM-140H-TP is a dimming ballast for about 90 USD each.
    it gets to be a convoluted path to just dim some fluorescent tubes.

    awright was on target with his suggestions....

    "If boatsman will provide us with a little more detail on what he is trying to accomplish, perhaps we can suggest a more practical strategy, such as simply switching off some of the lamps if it is a large room illumination task or purchasing dimmable compact fluorescent bulbs and fluorescent-compatible dimmers if it is a small room situation.

    awright "
     
  11. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,348
    Hello,

    As said before conventional dimmers will not be able to dimm the fluorescent lamps.
    You will need special controls inside the flourescent lamps to make it dimmable.
    There are electronic "ballasts" for the flourescent tubes that work at high frequencies ( about 40 kHz ) that have a dimm control input.

    Greetings,
    Bertus
     
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