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Discussion Starter · #1 ·
I am playing around with making an ODNO fixture from a BallastWise ballast that is spec'd for either 2 x 13W, 2 x 9W, 2 x 7W or 2 x 5W biax bulbs (http://www.ballastwise.com/item.asp?PID=62&FID=16&level=1). The plan is actually to use 2 of these ballasts, each driving 1 x 9W bulb.

I have verified that the ballast is ODNO capable using a cheap light meter (a 35-41% gain seems to agree with what others have posted regarding ODNO), but was thinking it would be nice to be able to flip a switch and have the ballasts go from ODNO to non-ODNO mode so I could adjust the light output. I'm actually worried I might have too much light (heat) and the configuration of the hood would not allow for me to increase the distance of the fixture from the tank.

I suspect that to do this would mean that in the ODNO configuration, each ballast would be driving a single bulb, but in the non-ODNO configuration (ie switch flipped), either (A) a single ballast would be driving both bulbs and the other ballast would be unused; or (B) each ballast would be driving one bulb but with one of the power drive wires disconnected.

(B) would be preferable as I could then switch each ballast / bulb pairing independently, but I tried a configuration using wire-nuts and it appears that the ballast will only light the bulb if both power wires (ie the blue wires) are attached to a bulb (in other words if both blue wires are attached to one pin of the bulb and the single red wire is attached to the other, the ballast starts successfully ODNO; but if only one blue wire is attached to the pin, the bulb just flickers).

Is this normal? Is there a way to run a multi-tube ballast in normal (non-ODNO) mode, but with only 1 bulb attached and the other power leads capped?

If any of you guys with a little more knowledge of electronics knows of an alternative way to achieve this effect, it would be greatly appreciated -- I have been experimenting but am worried about blowing something up.
 

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BallastWise ballast that is spec'd for either 2 x 13W, 2 x 9W, 2 x 7W or 2 x 5W biax bulbs
Some rapid start ballasts are spec'd for two bulbs, and will not light a single bulb. I guess that's what you have here, and there is no way to do what you are intending to do.
 

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Discussion Starter · #4 ·
Not such a good idea...

To close the loop here, there is a easy way to wire this using a 4 pole switch, but based on posts over in the DIY section, it sounds like this is pretty difficult to implement because of fire risk related to arcing.

Apparently the starting voltages of ballasts are very high (in my case 750V), which makes finding appropriate switches and getting them wired approriately a problem for a casual DIYer.
 

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It would be a simple procedure if the switching were only done with the power off. And, that is doable with just a minor bit of ingenuity. Wasserpest could work out that system in his sleep!
 

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A non arcing high voltage switch would work. That would cost a large though. And, I wouldn't trust a used one.

Two suggestions. Spend the money for a two tube dimable ballast and dimmer switch.

If that is too much money, can you fit three bulbs and ballasts in? Two on one switch and one on another switch.
 

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Discussion Starter · #7 ·
A non arcing high voltage switch would work. That would cost a large though. And, I wouldn't trust a used one.

Two suggestions. Spend the money for a two tube dimable ballast and dimmer switch.

If that is too much money, can you fit three bulbs and ballasts in? Two on one switch and one on another switch.
Y, I had tried to find a quad-pole switch that could isolate 1kv unsuccessfully. Ultimately, just seemed like it wasn't the safest thing to be messing around with.

This is for a Fluval Edge so there is very little space in the hood, even removing the stock MR11 halogen fixture. 2 x 13W bulbs might fit widthwise, but just barely, and I was concerned about heat issues given limited clearance on the left and right (hood is plastic). I guess I will play around with it more over the weekend as it seems like ODNO won't be possible .

Regardless, appreciate the suggestions.
 
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