Florescent Lights

[JohnMC]

Just a couple of quick questions for anyone who knows. I would like to build a few florescent lights, I have finished a few case designs, but need help with something else.

Question One: Can you dim the "output" of a ballast (before it goes to the lights)? Is it just DC power coming out?

Question Two: Does anyone know of a dimmer that will work with dimmible florescent ballasts' that is DMX controlled? I need something that would work with a NSI type system.

Any help with this would be greatly appreciated.

John

 

[Jeff Anderson]

John if he doesnt come across your post here, contact Andrew at Coollights if you havent done so. He is a get source of knowledge in the field and quite willing to share.

 

[Cool Lights]

I published a video on the subject of building your own fluorescent film/video lighting early last year. On my site, blog and vlog we continue that with updated information as an ongoing edition to the video.

In general, you can't dim flos of any kind dimmable or not with a line voltage dimming solution--but for one rare exception made by Advance Transformer Company. Nor can you dim via hooking something up to the output voltage of the ballast. It's a bit more complicated than that and gets even more complicated if you want to add DMX. Dimming is one layer, DMX is another. Most dimmable flo ballasts work from a control voltage input that translates from 0 to 10v (and sometimes 1v to 10v--its a long story) being from completely dim to fully bright respectively. For manual dimming, you typically have a special potentiometer input to the ballast to regulate this 10v signal to the level that translates to the brightness you want.

Another layer of complexity is added with dmx and you'll have difficulty finding a suitable DMX controller that basically takes the DMX commands from the line and converts them to a 0 to 10v control voltage for the ballast. Single board microprocessor controllers are involved and are in the $100 range and above--and difficult to find too.

On top of all that dimming ballasts are typically in the $150 range each and only drive 2 tubes a piece so a 6x55 would cost $450 for ballasts alone. Its easy to see why dimming flos are more expensive and especially when DMX is involved. When you want both a manual dimmer and a DMX at the same time then its even more complicated.

There's a place in my discussion forum where I talked a bit about this whole subject of 55w tube ballasts both dimmable and non. I'll repeat it below:

The 55w ballasts are in the class of T5HO and there are several good ones that can work for a 55w project. You'll want the ones that specifically state they work with either F54 54w T5 tubes or FT55 tubes which are the classic biax like Cool Lights uses. Of course you can get both dimming and non-dimming versions with the dimming ones being the most expensive by a large margin. You always want to get the 2x55 versions that drive two tubes as the cost ratio is better on them than the ones that drive one tube alone. Here are some good ones that work well separated into dimming and non-dimming versions:

Non-dimming
Advance Centium ICN-2S54 Intellivolt model which works from 110 to 277v so it can work anywhere in the world.
Universal B254PUNV-D also universal input voltage.
Sylvania Quicktronic QTP2X54T5HO/UNV (universal input voltage)
Fulham Workhorse 5 (110v or 220v models)

In dimming we have two categories: the 0 to 10v which require a control voltage from a special dimmer to operate them or the Inductance type which you can actually use an inductance dimmer or motor speed controller on the 110v or 220v going into the ballast like you can with a tungsten light--as you do so, you get dimming on the fluorescent lights being driven by the ballast. Very cool stuff but rare to find and very expensive. The 0 to 10v are still very expensive but less rare and available from more sources.

Dimming (0 to 10v models)
Advance Mark 7 RZT-2S54 120v (or 277v for other countries than USA)
Sylvania Quicktronic QT2x54/120 PHO-DIM (or QT2x54/277 PHO-DIM outside of USA)

Dimming (inductance type)
Advance Mark 10 REZ-2S54 120v (inductance dimming version) (or get the 277v for elsewhere outside of USA)

Phillips and Osram make some nice dimming ballasts but for the most part, these are only available in other parts of the world besides the USA.

Also, always double check to make sure you've got the model that works in the USA or whatever country some others may be in. There are some models in the same line which work with 380 volts and some other odd combinations which are totally unusable for most people.

So where do you get all these. Well typically from a professional lighting supply in your city or sometimes can find them online too. I occasionally caught some of the Advance non-dimming ones on Ebay for around $15 to $17 each with shipping and that's a very good price. Ebay will allow you to find some on clearance or surplus type deals. Cool Lights is selling the non-dimmable Sylvanias now. Otherwise, if you pay anywhere near retail, your paying around $50 for non-dimming ones and $160 for dimming ones.