Timer for Zone VI Cold Light?

[timlayton]

I just picked up a zone iv cold light with stabilizer and I've been told that I need to make sure I get a proper timer that can handle the inductive load. Any suggestions or advice?

Thanks,

Tim

 

[RalphLambrecht]

Tim

Your timer choice should be guided by your working preferences not your light source. For example, f/stop timers have so many advantages over regular timers that I would not consider a regular timer for a new purchase or buy a light source incompatible with them.

Two sources for f/stop timers are RHDesigns (www.rhdesigns.co.uk) and Darkroom Automation (www.darkroomautomation.com), both are contributors to APUG.

 

[Doremus Scudder]

IIRC, the Zone VI stabilizer handles the main part of the load, and simply has an "outlet" for a timer/switch. In that case, you can use any timer or a foot switch without worrying about load, since the timer simply switches the stabilizer on/off.

As good as f-stop timers are, I still use a metronome and percentage calculations with great success... I don't even have a timer (I really dislike them), I just set the metronome on 120, step on the footswitch and print away. Of course, you have to count seconds, but you can keep your eyes on your work more easily.

BTW, I use a Zone VI stabilizer for controlling the light source on one of my enlargers and it works well.

Best,

Doremus Scudder

www.DoremusScudder.com

 

[RalphLambrecht]

I use the metronome for exactly those instances (as Doremus said) when I need to keep the eyes on the work. In all other cases, I find the constant ticking too annoying.

 

[Nicholas Lindan]

You can use the ZVI cold light stabilizer with any timer. Older Aristo's were said to have ballasts with excess inductance, but this seems to have been more worry than reality.

 

[Luseboy]

I really like my gralab 545 w/ footswitch. I use it with my aristo cold light head with no problems what so ever. I also very much like the kearsarge timers, but i prefer the gralab because footswitches are cheap! you can just buy a tape recorder footswitch for less than 10$ off ebay. it beats spending 60 on a treadlite (even though they feel great under foot)
-Austin

 

[vpwphoto]

I've been using a Besseler Electronic timer with mine for years.

 

[RH Designs]

Our timers work fine with the Zone VI head. For the older unstabilised versions we do a compensating version.

 

[ZoneIII]

Personally, I don't like f/stop timers at all and, IMO, they are hype. I realize that that is not the subject of this thread but I noticed that the first response did not answer your question but rather praised f/stop timers instead. I have used one but would never think of buying or using one in the future. I find standard timers to be much more intuitive and easier to use and allow for finer control. I have sometimes suspected that f/stop timers were a solution searching for a need. But hey! Each to his own.

As for the load consideration: It's nice to know that it is safe to use all timers with Zone VI cold lights but if there is any doubt, Aristo made a contactor to isolate the delicate circuitry of some digital timers. I have used one for years on one of my enlargers. It's really just a remote switch that closes a circuit to turn on the enlarger lamp while bypassing the timer. They sometimes come up on eBay but I suppose similar generic devices are available through electronics supply houses. I have an extra one and I may put it on eBay soon.

I question the post that says that you don't need one (with some timers) if you are using a Zone VI Cold Light Stabilizer. Out of curiosity, I just went down to my darkroom and reviewed the wiring of my stabilizer and timer. The Stabilizer gets it's AC current from the timer. It is not plugged into an AC outlet. The only connections it has are to the cold light, the sensor, and the timer. In other words, they are wired in series. The timer is still supplying the current to the cold light except the stabilizer is wired in series with it to regulate the current to the cold light depending on variations in the light output of the cold light that the sensor detects. I am definitely not an electronic's person but I think that means that if you have a timer that cannot handle the inductive load of a cold light, adding a stabilizer does not eliminate that problem. It would have to have it's onw AC connection to do that.

I have an Aristo 1200 contactor in the circuit that really does isolate the timer. It plugs into an AC outlet which goes to the cold light. In that setup, the timer merely closes a circuit in the contactor but it is the contactor that handles the load to the cold light using its own AC source. My timer with that enlarger is a Gralab 450 (with the light blue expose bar) and I asked the folks at Gralab at the time I bought it if it could handle the load of my (then) Aristo cold light and they advised me to use a contactor or risk burnign the timer out. I have used the contactor ever since, even after switching to a Zone VI head so I could use the stabilizer. But I believe that some later versions of the same timer did not need to be isolated from the load of the cold light.

My other enlarger uses a Zone VI compensating timer which can handle the load of a cold light with no problems, of course.

Digital timers are expensive so if you have any doubt, you may want to isolate it from cold light load. It can't hurt anything and it may save an expensive digital timer from being fried.