Omega Timer With Aristo Cold Light?

[ic-racer]

These coldlights have a big transformer that takes 120V up to almost 500v. I suspect these transformers come from the 'neon light' industry. When you first turn it on, there is somewhat of a power surge, and I believe this is what they are referring to with the 'inductive load.'

There was so much extra room in my Aristo power supply case that I was able to put a big relay in there. Now my timer just powers the coil of the relay and I don't have to worry about potential damage to my timer. I added a 3 way switch so I could bypass the relay if I wanted.

http://www.largeformatphotography.in...5&postcount=19
http://www.largeformatphotography.in...6&postcount=20

With the heater on, I measured pretty constant temperatures. I did not notice any change in temperature or print quality over the course of a printing session. http://www.largeformatphotography.in...5&postcount=43

Here is an example of the heater and thermostat, if you have not opened yours up to check it out : http://www.largeformatphotography.in...2&d=1202923345

Yes, get the diffuser as close to the negative as possible, otherwise it will form a hotspot in the middle. I went to a lot of trouble to make mine as close as I could get it. http://www.largeformatphotography.in...6&postcount=29

[Claude Sapp]

I had this setup at one time. I built my own contactor loop to handle the load. All that is needed is a DPST NO 10 amp contactor with 120 volt coil...let the timer enlarger lamp outputs supply the coil voltage and have a live 120 volt sitting on each of the double poles of the contactor. Probably a lot less expensive than Aristo's contactor. Any HVAC supply house would have the contactor that you need.

I have always wondered why my Omega timer never worked quite right with my Aristo heads. It sort of works, but will not shut off completely after the timer has shut off, the coldlight still burns very dimly, it does not shut off completely.

Donald, is the contactor a plug in affair, or does it require wiring?

[tgtaylor]

Hi IC-Racer,

Believe it or not, but not more than 30 seconds before I was notified of your post I bought an ARISTO SOLID STATE CONTACTOR MODEL 1200 advertised as brand new off ebay for $45 "buy it now" (+$10.00 and $3.71 tax) or $58.71 total. The Calumet website list it for $99 + shipping and tax so if it truly is "brand new" I got it for half price and about $5.00 more than getting the devise from an electrical/HVAC source as recommended by Don in an earlier post. (Thanks Don, I was seriously considering that until I just happened upon the ebay post a few minutes ago.)

I never received a reply to my email to either Aristo or Omega Satter and Wednesday I called Omega and spoke with their tech Greg who said that he didn't know whether the ET-500 would take the inductive load (i.e., change of polarity) of the Aristo and was sending off for the schematic and would let me know NLT tomorrow (Monday). Naturally, now that I bought the Contactor, he'll call tomorrow and say that Omega built the ET-500 specifically to handle inductive loads!

The issue now is whether to invest in the (Horowitz) stablizer as recommended by Ansel Adams in "The Print" which I am now reading. Is the stablizer needed with the new V54 head?

Thomas

[Merg Ross]

Thomas, the contactor should do the trick for you, good price. My experience is that after about a fifteen minute warm up time, the V54 stays consistent throughout the printing session. I usually print for six or eight hours at a time and have not had a problem with consistency. Once you get set up, give it a try, you may find the same to be true.

[tgtaylor]

That's good news Merg!! Thanks.

[ic-racer]

The issue now is whether to invest in the (Horowitz) stablizer as recommended by Ansel Adams in "The Print" which I am now reading. Is the stablizer needed with the new V54 head?

Thomas

I think that may depend on where you live. I make an analogy to a water filter. Where I live, the faucet water has never been a problem, and a darkroom water filter is near the bottom of my to-do list. Likewise, my line voltage seems pretty constant.

I guess you could monitor your line voltage over a few weeks or months and see. Maybe someone with one of those coldlight voltage stabilizers can comment on its value.

[Eric Woodbury]

I have some data of v54 light output vs time with heater on and with varying amounts of light-on time. It is fairly consistent, but if you were printing high key images with extreme sensitivity to threshold values, I suspect you'd still have problems with runs of several prints.

I don't have light output vs input voltage. My voltage is a consistent 117VAC, but I know that this is not the case for most people.

I will try to find the data and get them posted soon.

[Eric Woodbury]

Here are the data. The temp is a thermometer in the light chamber and the brightness units are just 'units' from a MetroLux. I hope the columns work out here.

You can see that if your on/off ratio is very consistent, then after an hour or so, exposures may be consistent w/in 1 or 2 %. This is usually fine, but as I mentioned, highkey prints with sensitive high value at threshold will trip you up. Threshold values are so exaggerated by exposure variations of the smallest magnitude.

November 20, 2006
V54 coldlight test
Light on continuously from 0 to 25 min, then off and only on for measurement lasting 30 sec.
Time Temp, F Brightness
0, 70, 45
0.5, 70, 50
1, 70, 59
1.5, 72, 69
2, 70, 77
2.5, 75, 82
3, 77, 91
3.5, 79, 99
4, 81, 106
4.5, 82, 111
5, 86, 117
5.5, 88, 122
6, 90, 125
6.5, 91, 129
7, 93, 131
7.5, 94, 132
8, 98, 133
8.5, 100, 133
9, 101, 133
9.5, 103, 133
10, 105, 132
15, 111, 127
20, 118, 124
25, 125, 121
40, 107, 117
50, 104, 115
60, 103, 115
70, 102, 116
80, 101, 118
90, 101, 119

[tgtaylor]

Hi all,

I got a voice mail from Greg at Omega/Satter this afternoon and he said that he heard back from Omega who said that the ET-500 timer will work with cold light sources and gave him no further elaboration. About the same time I got an E-mail from the guy on E-bay with the tracking number of the Contractor. So I'm going to connect the Contactor to the timer anyway. If it works for Merg, it (better!) work for me.

Now that that's taken care of, time to get down to business. I saw several great B&W shots yesterday but because of the time and lighting couldn't take them. But this weekend...

Thanks all for the help on this. I owe you one (or two)!

Thomas

[Merg Ross]

Thomas, I bet the contactor will work just fine.

By the way, for you and others in the Bay Area looking for photo equipment, a good source is the Hayward Camera Show sponsored by the East Bay Camera Collective. The next one is this Sunday (3/30) from 9:30 to 3:00 at Centennial Hall located at 22292 Foothill Blvd. I have been there a couple of times and there is always a good variety of equipment.