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Solux Lamps

Discussion in 'Lighting' started by Roger Breton, Aug 15, 2003.

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  1. Roger Breton

    Roger Breton Guest

    This morning, I made a series of color measurements on Solux
    50W/35degrees/4700K bulbs using a variable AC and DC voltage generator. The
    results are as follows (chromaticity measured with a Minolta ChromaMeter I):

    V x y CCT
    --- ---- ---- ------
    12 .363 .372 4478
    12.5 .359 .369 4597
    13 .356 .367 4675
    14 .348 .362 4929

    V x y CCT
    --- ---- ---- ------
    12 .349 .365 4905
    14 .335 .353 5399

    I was trying to test the manufacturer's claim of 4700 K.

    Is anyone using these bulbs for museums or art gallery? And what kind of
    special power supply do you have to use to drive these bulbs?

    I am interested in putting together an affordable viewing environment for my
    graphic design students who need to prepare artwork for printing on offset


    Roger Breton
    Laval Qc
  2. Someones got to ask sample size and distribution wether there all same batch
    code / date of manufacture or a spread and perhaps as versus a major brand
    `standard` MR16
    If your using a lab power supply AC will be 50/60 hz probably?
    Lot of electronic switching transformers in LV lighting installations are
    AC in the Khz.
    No idea if this makes a difference to colour temperature but interesting to
    see the colour
    temeperature rise in DC operation as well.

    No association with Solux at all, just interested in the comparison.

  3. What meter (brand and model number) did you use to measure the AC
    voltage? There is no reason why the CCT should be as different as you
    have reported for the same voltage (DC vs. RMS AC)
  4. Remember that RMS is defined in such a way that an AC voltage of X
    volts RMS has the same *heating* power as X volts of DC. Assuming your
    meters are properly calibrated an incandescent filament should operate
    at the same temperature using 12 volts DC as it would on 12 volts RMS
    AC. (Ignoring for now the second order effects associated with the
    fact that the resistance of tungsten is a function of its temperature.
    I say these are second order because at 60Hz I do not expect
    significant variation of the tungsten temperature over a 60Hz cycle.
    The resistance over a 60 Hz cycle should be especially small for a 12
    volt filament due to its relative high thermal mass, but might be more
    significant for a 240 volt filament that has lower thermal mass.)

    Since the definition of RMS insures equal heating power for 12 volts
    DC and 12 volts RMS AC, and an incandescent filament is a thermal
    radiator, your measurements seem to indicate an instrumentation error.
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