Voltage regulator

[Terrence Brennan]

What is considered to be an acceptable output regulation for an enlarger lamp? I am looking at an inexpensive voltage regulator, which has an output regulation of +6 to -12%.

The problem is that I am suffering slight inconsistencies from print to print, on all three of my enlargers, a B-22, a B-22XL and a D-6. All three use different timers. The two B-22s are fitted with the standard PH111A lamp, 125 volt, 75 watt, and the D-6 fitted with a PH212 lamp, 120 volt 150 watt. My paper (RC) is processed in a modified AGFA Rapiline processor, so I don't suspect processing variations.

One of the types of prints I make is simple snapshot prints, either 4-up 4x5 or 3-up 4x6, on a single sheet of 8x10 paper. When I make 3-up 4x6 prints, typically the first is fine, based on my test, the next is ever so slightly lighter, and the third is lighter still, enough for even a snapshot to be discarded. Even if I make another set of three prints and process them at the same time, I get the same results.

I also have cases, with all three enlargers, where I make a test, increase the exposure, and sometimes get the second test slightly lighter. If I have a test where where I decrease the exposure, I sometimes get the second test slightly darker.

The fact that there is no consistency as to density drift, and all three enlargers exhibit the problem, I suspect lamp voltage changes, but I cannot be 100% sure. Could it be the lamps are all aging?

Anyway, I am looking at an inexpensive voltage regulator. Industrial strength voltage regulators seem to sell in the thousands of dollars, a bit rich for my circumstances. This is a link to the voltage regulator I am considering: https://download.schneider-electric...Ref=SPD_ASTE-6Z7V37_EN&p_enDocType=User+guide.

If any of the APUGgers have some thoughts on this, I would appreciate hearing from you. I do recognize that is can be difficult to troubleshoot a problem, based only on my observations, with precious little hard data available.

 

[AgX]

What about feeding the enlarger not from the mains, but from a Lead-battery with a step-up inverter? The battery itself is hooked up to the mains by a charger.

However here the problem is shifted to the voltage stability of the battery. Which means the battery must be large enough that the drop in its voltage during feeding the enlarger is tolerable.
Maybe the step-up inverter is selfregulatory enough to compensate the battery-voltage drop.

To spare the charge of the battery one might use this battery feed for metering and exposure only.

 

[ic-racer]

Do you have a voltmeter, have you verified by how much the voltage changes during the day or from minute to minute?
That does look like a regulator that you could use for an enlarger, but realize it would only limit a spike to 127V (from 120 nominal).
Also, according to this generic diagram, you would need a 20% increase in voltage to get one stop more exposure.
10% increase is 1/2 stop, 5% increase 1/4 stop.
So that 6% spike that the device can manage is only about 1/4 stop change, and that assumes the spike continues through the entire exposure.

 

[DWThomas]

In the early days of small computers, it was not uncommon to have a "constant voltage transformer" (CVT). These used some magic tricks with ferroresonance to provide voltage regulation approaching just a few percent. In a quick look, it appears they still are made, but they are pricey.

Here's one by Tripp-Lite. I vaguely recall there were some that included a bit of waveform filtration because the most basic units sometimes put out a somewhat ratty waveform. To drive a lightbulb that likely wouldn't matter.

Another one-time maker was Sola, but that maker has rumbled through a bunch of various owners and I'm not sure they still offer CVTs. I happen to have one good for 150 VA that I think came from the dissolution of a start-up decades ago. I have used it but not in a long time. That sucker probably weighs 7-10 pounds, there is a lot of iron in them.

The unit

Nameplate

A sense of scale (1 liter measure)

 

[Doremus Scudder]

Correct me if I'm wrong, but aren't voltage stabilizers fairly common and easy to acquire? I would think that that would solve the problem easily.

Still, variations of lamp brightness with age would be present, but those would vary slowly over time, not substantially from one print to the next.

Best,

Doremus

 

[Hilo]

Have you excluded the AGFA Rapiline processor as a cause of the problem? If not, just tray process for a while.

If the problem is still there, I would talk to an electrician about your situation.

 

[koraks]

When I make 3-up 4x6 prints, typically the first is fine, based on my test, the next is ever so slightly lighter, and the third is lighter still, enough for even a snapshot to be discarded.

Is the progression always like that? I.e. the prins get lighter and lighter? If so, it's very unlikely to be a voltage stability problem. In fact, that's quite unlikely anyway. I'd start by looking at other factors in the imaging chain first.

 

[Paul Howell]

Check on Ebay for a Bessler or Omega voltage regulator that were used with color heads. I have a Bessler, it does drop the line voltage a bit, so exposure times are somewhat longer.

 

[gone]

Have you measured the voltage to know that it's being inconsistent? I would start there, we're just assuming that it's a voltage issue, but by measuring it w/ a simple but accurate volt/ohm meter over the course of a few prints, you should know something for sure one way or the other. Personally, I suspect the problem is somewhere else. It seems unlikely that a voltage drop would occur that consistently as you mentioned, w/ it growing weaker as you make several prints? Anything is possible, but that sounds like a more remote possibility.

 

[beemermark]

What about feeding the enlarger not from the mains, but from a Lead-battery with a step-up inverter? The battery itself is hooked up to the mains by a charger.

However here the problem is shifted to the voltage stability of the battery. Which means the battery must be large enough that the drop in its voltage during feeding the enlarger is tolerable.
Maybe the step-up inverter is selfregulatory enough to compensate the battery-voltage drop.

To spare the charge of the battery one might use this battery feed for metering and exposure only.

Buy a UPS from the computer store. Not that expensive and accomplishes what AgX proposes. https://topxperfect.com/top-best-ups-for-computer-reviews/

 

[AgX]

I guess off the shelf UPS may have too much voltage tolerance to the aim value, but I would to have look into this.

 

[Mal Paso]

Tripp Lite Voltage stabilizers seem to be about $50 for 600 watts on ebay.

My LED head is 24Volt so I was able to use a $25 switching power supply for stable voltage.

 

[4season]

What is considered to be an acceptable output regulation for an enlarger lamp?

DWThomas has the right idea: Constant-voltage transformers would be an excellent choice, offering much better regulation than the unit you've linked to. This is real old-school technology, and inside the housing is nothing more than a ferroresonant transformer and a capacitor. Works great but can be quite expensive unless you scroung around for a deal on a used one. Here's an example of a modern unit:



The APC device you've linked would certainly be better than nothing, and it's a lot cheaper than a CVT, though it doesn't offer the same degree of regulation.

For the enlargers you've mentioned, 250 VA capacity would be plenty

 

[beemermark]

I guess off the shelf UPS may have too much voltage tolerance to the aim value, but I would to have look into this.

Your computer is far more sensitive to voltage fluctuation then a light bulb will ever be.

 

[koraks]

Your computer is far more sensitive to voltage fluctuation then a light bulb will ever be.

Certainly not. Look at how a modern SMPS works (which powers your computer). You'll quickly notice it'll be OK with voltages fluctuating way beyond what you'll ever see in a typical American home.

 

[AgX]

Your computer is far more sensitive to voltage fluctuation then a light bulb will ever be.

Yes, as the light bulb, but not as the colour paper!

 

[Chan Tran]

Your computer is far more sensitive to voltage fluctuation then a light bulb will ever be.

Not many computer would work with voltages from 80 to 260V..
For good voltage regulation I would try to change the bulb to 24V and supply the enlarger with regulated DC power which is much more stable.

 

[DWThomas]

Your computer is far more sensitive to voltage fluctuation then a light bulb will ever be.

That's hardly a universal truth these days. The internal workings may be sensitive, but most computers, at least home and small business sorts, have a switching power supply which can take a wide range of input and supply a regulated output. Typical laptop supplies are rated for inputs from around 90 to 240 volts, 50 to 60 hertz. They work just about anywhere in the world -- if you can find the right plug adapter.

 

[AgX]

But why then has so far nobody linked to a cheap, solid state regulator of 150W output?

 

[faberryman]

You might want to contact your electric company. I had a fluctuating voltage problem, and the electric company put a recording voltage monitor on my line to confirm it, and then replaced the transformer on the pole behind my house.

 

[~andi]

Here's another thought: How long are your exposure times? With short times fluctuations become more apparent. Maybe if you extend them a little to, say, 20 or 30+ seconds, those fluctuations may become less of a problem?

 

[gordrob]

I have an extra Unicolor Solid State Voltage Regulator Model 744 - 400 watts - output 100 volts +/-2%. If it is of interest to you send me a PM for details.
Gord

 

[koraks]

output 100 volts +/-2%.

That won't do much good for a 125V bulb.

 

[AgX]

And I wonder what a 100V regulator was intended for.

 

[Jim Jones]

100V was and perhaps still is the standard in Japan.