Identical dimmers different result

Discussion in 'General Electronics Chat' started by Andrew Leigh, Mar 11, 2015.

  1. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
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    2
    Hi,

    I have two identical 220vac lamp dimmers capable of a 500W load.

    The one is coupled to an incandescent lamp sequence of 14 x 40W = 560W and although over the top has worked perfectly for 3 years.

    Recently I took the other identical dimmer, still unused, and coupled this to a 250W Halogen Spot light. It acts like a strobe with intervals of about 1 second and fails to reach any significant brightness.

    Do these dimmers not power halogen type loads?

    Regards
    Andrew
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Halogen needs time to charge up to full brightness I believe
     
  3. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
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    2
    Ha, let me rig a normal incandescent and see what happens. Why am I always wrong :D.
     
  4. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    OK connected dimmer to normal 100W incandescent lamp and it still slowly pulses. I have to assume that the dimmer is faulty, would this be a fair assumption?
     
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Yup!
     
  6. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    As a point of interest, it's (barely) possible that the thyristor was damaged by the 250W lamp's inrush demand (altered triacs, for instance, occasionally exhibit high 'on impedance' with corollary 'on state' heating and (significant) transient alteration in triggering characteristics.

    That said the unit was probably 'DOA' as you surmise...


    Best regards
    HP
     
    Last edited: Mar 11, 2015
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,566
    2,379
    I would agree it could be faulty, Being a 500w version, was this originally intended for power tool control?
    If so did you try on something of this nature?
    Max.
     
  8. crutschow

    Expert

    Mar 14, 2008
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    Halogen lamps have a tungsten filament, the same as a standard incandescent lamp, so they have similar turn-on characteristics, although halogen lamps run at a hotter filament temperature, so they may have a lower cold resistance, hence higher start-up surge current, for the same lamp wattage.
    Otherwise the main difference is the gas in the bulb.
     
    R!f@@ likes this.
  9. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Thanks chaps. Will get a new one tomorrow.
     
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