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ODNO Clarifications and questions

2K views 1 reply 2 participants last post by  Rikko 
#1 ·
I have been reading on and off about ODNO (over-driven normal output) lighting for over a year now, and find that there are questions that are never asked or answered. In the hopes of reaching a level of understanding i can be comfortable with to apply this technique, i'd appreciate help from anyone who knows the answers!

First of all is the common statement that you can put 18", 15W T8s onto an electronic ballast and overdrive them. As i look around (for example, bulbs.com), the only 18" T8s that i see are 'preheat' tubes intended for use in the old cheap-o desk lamps and under-counter lamps that use magnetic ballasts (the annoying ones that require you to hold down the starter button for a few seconds). Furthermore, these tubes are rated at significantly lower lumens and lifetime than the slightly more power-consuming 24" version (F17T8). When people talk about overdriving F15T8s, are they talking about these preheat bulbs, or some intended for instant start electronic ballasts? If these are the bulbs that people are using, then does using an electronic ballast increase the lifetime and output of the bulbs (without overdriving)? In other words, is the large difference in ratings between the F17 and F15 simply because one is intended for magnetic ballasts, and the other for electronic?

Second, i know that the modern T5 lamps are intended to be used only on special ballasts with "end-of-life" circuitry. Are PC lamps (bent T5s, after all) exempt from that need?
- If so, can i pick up a 40W or 36W four-pin PC lamp, plug it into a 2G11 socket (where would i get one), and hook it up to a 4xF32T8 ballast, and have it work according to spec?
- If not, does that mean i can run linear T5s from a 4xF32T8 ballast?

Finally (and unrelated), does anyone sell nice reflectors (similar to AHsupply's) a la carte? Perhaps by the foot? If not, why the heck not?

I'm trying to figure out how to light a new 10gallon tank, and the approach i take depends a lot on these questions, so thanks in advance for your help.
 
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#2 ·
Ok, some good questions here..

First, the T8s you see are 'preheat' tubes. Yes. The "intended for use in..." line is really just a bunch of crap. It means they can operate in a magnetic ballast - but that's meaningless. They can run in any fluoro ballast. A magnetic ballast typically works by applying power to both pins at each end of the tube. Notice how they get a little red before the bulb fires? It's generating heat which excites the electrons enough to allow them to flow at the applied voltage. An electronic ballast brute forces the bulb into firing by shoving a ridiculously high starting voltage at one end which is high enough to traverse the bulb without needing to "warm up".
A fluorescent tube is a fluorescent tube is a fluorescent tube. Only difference between using a magnetic or electronic ballast is that with (all?) electronic ballasts the two pins at each end of a bulb aren't necessary - you just need the one to send in power.

The F15/F17 thing is basically an efficiency "hack" that was made some time ago to reduce power costs in offices. T8s especially are very energy efficient, and many offices replaced their F40 bulbs with F37 (or was it F32?) - same length of tube, less power draw.

Either works to ODNO, with varying effectiveness. I expect the more efficient bulb (ie. lower wattage rating) will probably produce a bit more light overdriven than the lesser one, but probably not too noticeably.

T5s are designed to work on "programmed start" electronic ballasts. I'm using them on an instant start ballast, and I'm sure they will also work on a dirty old magnetic ballast. The reasons for using programmed start only are mainly for bulb lifetime, but I've yet to see a detailed and scientific explanation as to why that is.
The "end of life" circuitry is there just to protect you from the bulb's decay. As T5s age their power draw increases (as with all tubes, but I think T5s are much more noticeable) - I read somewhere their wattage draw doubles while their lumen output stays about the same. If you're running a 59W T5 on a 60W ballast, imagine what that would do!

I'm not terribly well versed with PC bulbs, so having no hands-on experience I'll decline to comment. Try a specialty lighting store/supplier for that socket. I have a great one near me that also does retail (www.albritelighting.com).

But yes, you can run linear T5s in a 4xF32T8 ballast. You can also run F30T12 bulbs in that ballast, etc..


If you can find ala carte reflectors let me know.. If they're cheap enough I'll take a dozen. :)
My SW LFS has aluminum reflectors ready to be installed in hood (they have VHO and VHO/MH reflectors pre-drilled) but they're not exactly what I need and a bit expensive.
 
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