Question on Ballasts in fluoros
 

Hi:

I had a question. Can a cheap Chinese versus an OSRAM, versus a KINO ballast for Diva or faux Diva fixtures affect the actual color temp of a lamp?

For example, if I get a cheap chinese 2/4/6-bank fixture, but I lamp it with Kino True Match lamps, will it give me some other color temp than what it is supposed to do?

In other words, is the lamp the sole determinant of output color temp, or is the ballast the sole determinant, or is it some combination.

Thanks

One thing which will affect your colour balance is the temperature. The contruction of the eastern copies leaves much to be desired when it comes to cooling and the reflectors tend to push a lot of heat back into the tubes. When the tubes get hot their green spike increases dramatically, even Kinoflos will have a tendency towards green (and they're normally slightly on the magenta side of neutral).

Likewise if the ballasts, in an effort to be "flicker free" don't allow the gases to "rest" for long enough, the tubes will increase in temperature. There doesn't seem to be any difference in performance (colour temperature-wise) between Kino and Osram flicker-free ballasts though. Mind-you that was just using a Minolta colormeter to check the balance, maybe hyper-sensititve lab equipment would show a slight difference.

This is from personal experience when I was buggering about testing various LEDs and Fluorescents for seminars. The idea was to be able to say with conviction... "you don't need to buy Kinos and Gekkos, you can get the same result with Chinese gear" but it became obvious that the opposite was the case.

Hi Guys,

A ballast is only in the circuit long enough to fire the tube. Once the gases have ignited, the ballest drops out of the circuit. Reflectors will have a bearing on heat but this is mainly "hot heat" or traditional temperature, colour temp is measured in degrees Kelvin, not strictly as "hot heat". Therefore, provided the ballast fires the lamp and ignites it, the rest is dependent on the lamp itself. i.e. if it's tuned to burn at 5000 degrees K, that's what it'll burn at. Hope this helps.

Here's a bit of info for you.

Kelvin Color Temperatures

Al

Ooh, don't think so.............
 

Not correct. The ballast controls the current and waveform going to the tube(s) throughout it's entire cycle.

The old inductive ballasts could, and did, do some weird and wonderfull things to the sinusoidal waveform between the in and out ports.

The new electronic ballasts can do even more ( read worse) if they're so inclined.

Dependent on design and manufacture, they can turn a sinus waveform into a sawtooth or just about any other shape they so please, thus significantly affecting how long a tube is in the ramp up and ramp down phase of operation.

I have a batch of fixtures here with "warm white" tubes and electronic ballasts, they're actually pink, and no, they're not faulty, just crap.

I have another set of the same fixtures, same manufacturer but different make of ballast, the "warm whites" are now blue!

So, as the original question was: can a ballast be responsible for a colour shift in a tube, the answer is, my word, yes.


CS

Oops.....
 

...I stand corrected........

bow... bow...scrape.... scrape.....

Al

PS.Could be those Kiwi ones are a bit queer.............. ;)

Don't worry, Alan............
 

They're actually.................drum roll.......................Chinese!

Queer, definately. Chinese most certainly. Crap, idubitably.

Ho Hum.


CS

I feel as if the Australian, Kiwi and English contingent here must all be electricians on the side. Thanks gents for enlightening me about the inner working of ballasts. When I built my own Kino knockoffs, I sourced a high speed, high quality fairly expensive ballast and I have been quite happy with the results with the Kino tubes but it is very interesting to hear about how the ballasts actually function. Thanks.

Dan

Thanks for the answers. It does seem like there are some conflicting opinions. At the least, it seems that color temp can be affected by ballasts (or should I type colour for the Commonwealth types).

Robin, so if I set up a color meter (Minolta II) on a stand and point my fluoro fixtures at it and get a reading after the light settles. And then I turn a fan on to blow across the tubes, cooling them, I will see a change in color temp? Interesting. I'll try that.

Dan:

I have some Chinese fixtures. I am thinking of replacing the existing ballasts with some good ones. Can you recommend some model numbers and approximate prices? Are they dimmable ballasts? Can you share any links to your project?

Thanks to all

If your lamp has efficient cooling, then there shouldn't be any difference since the design of the unit and reflectors is doing its job. But if you can work out a way to increase the heat of the tubes without damaging your unit, you will see a shift towards green.
The Kelvins will hardly change at all, just the green content.

In the case of your oriental units, it's probably cheaper just to bung a bit of minus green gel (a quarter or even an eighth) in front of it rather than start replacing ballasts.

In general the mixture of phosphors in the tube is the main factor. Very badly designed or faulty ballasts can create a pinkish glow at one end of the tube and shorten lamp life. Pretty decent explaination of all things fluro here: Fluorescent lamp - Wikipedia, the free encyclopedia

yeah, but I love to hack things. Mostly, I want dimming capability. The current ballasts do not have that. So, Dan, do you have a link to your projects or can share the model #'s that you used? Thanks, Mike

The ballast that you're after is an Osram QTI 2X28/54/220-240 DIM UNV1.
OSRAM|Professionals|ECG|ECGs for FL and CFL|Dimmable ECGs with 1...10 V interface|QTi...DIM-T5|index

That one will run 2x 55W tubes. Dimming control is by 0 to 10V analog input. Pretty certain Osram have a dimmer module designed to mount in a wall plate that can be cut down very easily to fit into a fixture. One module will control at least 3 ballasts but darned if I can find the module on Osram's site.
For my own instruments I made up a very small zener diode regulated 10V supply with a pot, realistically you cannot dim these tubes below around 10% or wierd things happen so my dimmer control does around 1 to 10V output.

Thanks Bob, but that seems to be the 220-240 volt model. I am in the US. I'll see if I can locate an equivalent model. But if prices for the US model are the same: 80 euros each, then wow! That may be a cost prohibitive change.

OK, here is the Sylvania brochure which shows the US voltage models:

http://ecom.mysylvania.com/miniapps/...FAM_BROCH1.pdf

pages 42-43 show the Helios line of dimmers. Pages 28-29 show wiring diagrams and a list of control manufacturers

OK: so I found this in a Kino Flo brochure. You were right.

The physical heat of the lamp directly influences color temperature and lumen performance and lamp life.
In order to maintain a stable color performance the lamp requires:
a cool spot at the tip of the lamp
a horizontal orientation
or a vertical orientation where the base of the lamp is above the lamp tip.