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  1. #11

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    Jan 2006
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    Los Angeles
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    rjas,
    I have the Vivek voltage stabilizer that you mention. And yes, it brings the nominal 120V mains power down to 100V. The net effect on any enlarger is that the bulb goes dimmer by a significant amount, since you are supplying a lower voltage. It works with regular enlarger bulbs (including halogen lamps), but I suspect the voltage drop comes with a corresponding shift of the bulb output towards the red-yellow. This may affect your B&W printing on variable contrast papers which are designed to respond to the blue-green spectrum. Perhaps not by very much, and which something consistent work habits can easily compensate for, but should still be mentioned.

    Color work may be another thing, since the voltage drop makes halogen lamps shift towards the warmer end of the spectral range. This is likely to affect your color balance and filtration settings. By how much I do not know. I have not printed in color using the Vivek voltage stabilizer since I have a Beseler dichroic head with a built in stabilizer set aside for specifically for color work (which I rarely get to do nowadays.)

    Changeling1: The Beseler Resistrol is actually a variable resistor (potentiometer). As an electro-mechanical device, it works by reducing current flow to the bulb, thus dimming light output. Worked great for graded papers, because it allowed fine-tuning by small exposure increments not quite replicable via stopping down the lens and/or by controlling exposure via the mechanical timers like Time-O-Lites and the subsequent Gralabs that followed. With today's variable contrast papers and their peculiar spectral sensitivity, and the spectral shift accompanying use of a line resistor, I'm not too sure. Besides, a solid state voltage regulator is much more efficient and consistent in controlling voltage spikes and line fluctuations. A potentiometer cannot accomplish that task.

  2. #12

    Join Date
    Oct 2004
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    You want to be careful about voltage stabilizers. Many less expensive ones only work on gross voltage differences. (I once bought a $100 computer "voltage regulator". Well, it would only regulation when the voltage fell below 90 or above 140. It was useless for photography. Whatever you get, test it with a voltmeter.) For color, you want as low a permitted fluxuation as possible. I believe that the only thing that really works is a Sola CVS transformer, or equivalent. These are big, heavy and expensive, although can be bought used, as they last a really long time.

  3. #13

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    Dec 2004
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    Unless you are already doing color printing and have actually seen a problem with your prints I seriously wouldn't bother. While you may see a momentary fluctuation in light output this probably has no effect since your exposures should be greater than 10 sec in length and a half second dip amounts to a few percent difference. Remember the power is not going off for a half second. But even in this case the error is only 5%.

    BTW, unless a stabilizer has enough spare capacity you can serious damage the power supply in the enlarger. Such damage would not be covered under any warranty.

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