Solanaceae
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That thing is unusually small based on its application... |
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Ash
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The capacitor is the actual ballasting element - The choke is there as a starting device and to drop the crest factor somewhat (otherwise the thing would destroy lamps in a blitz) |
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themaritimegirl
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It still has to have as much as 0.43A go through it, though. Yet it's smaller than a 0.16A T5 choke. |
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Ash
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It does not have to be of high inductive value, so much lower number of turns..... |
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ultralume
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How does that choke power a 40 watt lamp from 120V |
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ultralume
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How does that choke power a 40 watt lamp from 120V |
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dor123
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40W can't operate at 120V from choke. It require an autotransformer ballast. |
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I"m don't speak English well, and rely on online translating to write in this site. Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
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xmaslightguy
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^homebuilt fixture
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With the capacitor it ups the voltage enough to work off 120v. The lamps are running somewhere in the 25w-30w range rather than 40w
Interestingly enough, with the LOA version (which has no thermal protection) when a choke goes up in smoke - and thus is shorted, the light will still light at probably half its original brightness, running of just the capacitor. |
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Colored Fluorescent's such as F40T12 Red or Green or Blue are awesome...
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ultralume
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Interesting. I suppose the capacitor is in series with the choke and line. I'm assuming that it's value is either too small or too large to resonate with the choke and cancel it's inductive reactance and overdrive the lamp |
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xmaslightguy
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^homebuilt fixture
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@ultralume:
Yep, capacitor is in series with the choke. Somewhere I read that it was a 4uf/200v. I had a fixture where one of the capacitors had went bad, so I used a replacement with those specs & it works fine. |
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Colored Fluorescent's such as F40T12 Red or Green or Blue are awesome...
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ultralume
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Interesting. I will try it. I'm assuming the capacitor maintains some voltage at zero crossover of the AC cycle and adds voltage to the mains to restrike the lamp. |
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ultralume
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I saw one of the LOA shop fixtures in operation. It seemed bright and did not appear to under drive the lamps, not to mention started the lamps quickly in cold weather. The simplicity of the choke and capacitor ballast is intriguing.. |
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xmaslightguy
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^homebuilt fixture
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@ultralume:
They do underdrive, I remember the box said something like "69 watts Total"
I do like the idea/simplicity of them, but my biggest complaint is the lack of thermal protection.
As for cold starting... depends on how cold, if its cold enough they'll flicker horribly til the lamps warm up(if its too cold for them to warm up you do risk frying the choke), and if it gets enough below zero (F), they won't do anything at all(which is actually good since it acts as a safety feature) |
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Colored Fluorescent's such as F40T12 Red or Green or Blue are awesome...
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