PDA

View Full Version : Convert coldlight timer to incandescent?



Fred R.
5-Mar-2017, 15:47
Greetings,
Is this possible?
Are they just paper weights now, w/o the head?
Fred

ic-racer
5-Mar-2017, 16:58
The transformer for a cold light will not power an incandescent lamp. New cold light lamps are still available http://www.light-sources.com/solutions/specialty-fluorescent/products/aristo/aristo-replacement-lamps/

Also, inexpensive cold-cathode systems have a revival (underneath "Tuner/Drift" cars) and may come to challenge LEDs in the 'homebrew' enlarger light source arena because you don't need a PMW power supply. Cold cathode transformer is a simpler device. Randy needs to get some of these and try them...https://www.oznium.com/cathode-kit#photos

Fred R.
5-Mar-2017, 17:35
Thank you for the response.
I remember Zone Vl had an attachment that would allow use of the cold light timer with incandescent bulbs. Never got one. I like the Zone Vl timer and would like to make use of it.
Fred

Doremus Scudder
6-Mar-2017, 02:35
Fred,

It would really help if you could provide some details about what brand/type of timer you are referring to. I'm not really sure what you are trying to do here.

Doremus

Will Whitaker
6-Mar-2017, 08:56
Thank you for the response.
I remember Zone Vl had an attachment that would allow use of the cold light timer with incandescent bulbs. Never got one. I like the Zone Vl timer and would like to make use of it.
Fred

But the purpose of the Zone VI timer(s) was to overcome the delay in coming up to full brightness that a cold light exhibits. Incandescent light bulbs don't have this problem, so I don't understand just what it is you wish to do. Perhaps you could explain?

Back in the days of Zone VI I was a newsletter subscriber and catalog junkie. I pored over those old Zone VI catalogs until the pages came apart and I don't recall such an attachment as you mention. Not surprising as the use of an incandescent bulb would have been anathema to Fred Picker who built a large part of his business on selling the virtues of cold light.

Eric Woodbury
6-Mar-2017, 11:06
Incandescent is consistent with voltage, so if your incoming voltage is clean, you should be fine without the transformer. To get the incandescent to work with the transformer would probably require some sort of phase shifter, maybe a 22 uF, 400 VAC capacitor in series with a 100 Watt bulb. I wouldn't try this unless you know what your doing.

[Coldlights are consistent with temperature. This is what the heater is for, but it isn't good enough on its own.]

Fred R.
6-Mar-2017, 11:29
Apologies for the information-less question.

Simply, I don't use cold light for printing any longer but want to use the Zone Vl compensating timer for incandescent printing. As for understanding electricity, transformers and capacitors, I'm a simpleton. I just want to know which plug to use.:) I may be asking how to drive a car across water.

Zone Vl had an accessory sensor(?) that was to be attached to one of the cables and placed/suspended near the incandescent bulb, hole to be cut in the lamp head. Shudda woulda coulda gotten one of those back then but I didn't want to cut holes in enlarger heads.

And thank you for your responses.
Fred

Will Whitaker
6-Mar-2017, 11:47
The Zone VI timer depended on a photocell to provide feedback to the timer circuit to adjust the length of the selected exposure to compensate for the reduced light output of a cold cold light. I.e., low output from the cold light would cause a standard "second" to be longer such that the exposure was compensated by a longer absolute exposure.

Without a photocell, your timer should function normally for everyday operations. Unplug the photocell from the timer. As I recall, the Zone VI heads with pre-installed photocells had a DIN socket on top of the cold light head. That cable terminated in (again, from memory....) a modular plug (like a landline telephone plug) in the back of the timer. Once the photocell cable is unplugged, try the timer and compare it to a known clock. You probably have a timer function on your cell phone you can use.

Without the photocell input, the timer should read standard seconds and function as you wish for incandescent lighting. If that doesn't work, let me know. I may have another solution.

Fred R.
6-Mar-2017, 12:39
Hi Will,
Without the photocell cable connected, the lamp merely stays on.
Fred

Eric Woodbury
6-Mar-2017, 13:19
Will, I think this is the Z6 Stabilizer. This forced the lamp to have constant output and thus time was time. Everything in standard seconds. The compensating timer came later.

FredR, Does the incandescent turn on? You just don't have a photo sensor? If you have the photo sensor in a coldlight, remove it and use that one. I really don't understand why you would want to use the stabilizer transformer to run an incandescent bulb. Makes no sense to me. You're light output is fairly steady. If this is the Stabilizer unit with the big transformer and the only problem is your missing a photocell, you can get one of those from an old unit or buy the parts (except you said you aren't that versed in electronics). Not a huge project, but because of how that transformer works, your light will be about one stop dimmer than without. The xfmr requires some headroom. And it is all for nothing except to say that you are using the transformer. If your power is crummy, then buy a voltage stabilizer, but don't mess with this xfmr. You're wasting your time. If your power is crummy and you need a timer, buy a MetroLux or equivalent. It will keep your lamp at full brightness and run with or without a photo sensor. (requires photo sensor for closed-loop operation, which you probably don't need anyway.)

Will Whitaker
6-Mar-2017, 13:32
If the early stabilizer, then yes, that's completely different. I had inferred that it was the compensating timer.

Fred, if you're dead set on using this timer, then I'm sure a solution can be found. But honestly, I would get a new timer. Personally I like some of the offerings that RH Designs has. www.rhdesigns.co.uk

But since I opened this can of worms, I'll try to follow up with a solution.

Will Whitaker
6-Mar-2017, 13:57
Fred, Can you confirm just which piece of hardware you have? A photo would be very helpful. Am sending you a PM also.

Fred R.
6-Mar-2017, 14:29
http://static.photo.net/attachments/classifieds/115/1151170-131961.jpg

It's apparent I'm beating a dead horse (forgive the image).
I'd like to use it because I have it. I have other timers. No way I could afford a new one.
I guess I'll look to sell the unit.

Thanks again.
Fred

Will Whitaker
6-Mar-2017, 14:39
Don't write off the horse yet.

Eric Woodbury
6-Mar-2017, 15:14
Completely different unit than I thought.

Yes, you should use this. Absolutely. It will work fine. Put a photo sensor (silicon photo diode with IR cutoff filter) on there and you're good to go. If you have a coldlight with a sensor, you can pull that out and use it. I doubt you can find an original equipment sensor, but I have never looked. However, all the pieces are available new from electronic supply places, too. Some assembly required. Do you have a soldering iron?

Chuck Pere
6-Mar-2017, 15:25
If you don't care about any monitoring of your light intensity maybe you can just put a resistor in place of the photo sensor. I'm not sure of the value the photo sensor resistance would be at the midpoint.

ic-racer
6-Mar-2017, 16:22
Thanks for posting the picture. I thought you had a cold light power supply.

Eric Woodbury
6-Mar-2017, 16:29
Chuck, not sure that works here. I'm guessing that the photocell for the Z6 unit is a silicon photo diode. That's what they used in the TikTok and the Stabilizer and the very few units that FP had made by Horowitz for AA, A Ross, and a couple others. This is typically operated in a zero bias conditions and as such, it looks like a very high impedance current source with no voltage from anode to cathode. I've been pondering a way to trick it, but without a schematic or addition info, not sure how.

Keith Pitman
6-Mar-2017, 16:32
Fred R is correct that the Zone VI Compensating Enlarging Timer he pictured (finally!) will not run without being pluged in to a photo cell or an electronic component that would fulfill that function. I remember hearing that Calumet sold a component that would replace the photo cell if you had an enlarger without a photo cell and the timer would work normally. Presumably Calumat's device plugged into the cable that would normally plug into the photo cell.

Doremus Scudder
7-Mar-2017, 03:13
Fred,

My advice: Since your timer seems to need a work-around, which may be beyond your knowledge and abilities (or at least beyond your comfort zone), and since that work-around would not make use of the light-monitoring sensor, which is the primary advantage of this particular timer, you may simply want to find a good used timer such as one of the more modern Gralab digital timers (I like the 450/451) and find a good home for your Zone VI timer, i.e., someone who would put the light-sensor function to good use.

There's a For Sale/Trade section on the forum that you might take advantage of, or you might simply try and sell the Zone VI timer on eBay or the like and take the money and re-invest it in a different timer.

FWIW, I recently picked up two Gralab 450 timers for less than $20 each.

Best,

Doremus

Fred R.
7-Mar-2017, 11:24
Sound advice, Doremus. Thank you.