Nova 3 front panel
hilpert at cs.ubc.ca
Fri Jul 22 13:16:21 CDT 2016
On 2016-Jul-22, at 10:39 AM, Vincent Slyngstad wrote:
> From: jim stephens: Friday, July 22, 2016 12:46 AM
>> On 7/22/2016 12:25 AM, Vincent Slyngstad wrote:
>>> I mentioned http://www.foxdata.com/blog/tag/nova-312/ to you earlier, which suggested the 28V bulbs. I also found
>>> which makes it clear that the voltage is likely a fair bit over 12V.
>> Thanks for the tips. I see that the foxdata site lamps don't appear quite as bright as the chookfest ones, which is interesting. I'm thinking now if I do anything it will be the LED route, so will evaluate that, as I agree opening the thing back up will suck.
> Those chookfest bulbs are doing just what I'd expect from 12V bulbs in a 28V circuit -- way too bright, and then a drastically shortened lifespan. (The right bulb can last for years; the wrong one for minutes.)
> I'm not a big fan of the surgery involved in LED conversion, though I understand why folks do it. Particularly if they, like Emil, have used the wrong bulbs and found themselves replacing them all the time.
> Somewhere, I have Oshino's write-up about bulb rated voltage and bulb operating voltage, but I do remember the lifespan varies as some power of the ratio, and it makes a huge difference. (There are also formulae for derating brightness, etc.)
Not to mention that the extra heat from a bulb run over-voltage can damage plastic front panels and light shrouds.
Even at the rated voltage, different bulb models can have a wide range of specified lifetimes,
from a few thousand hours to 25,000 or 40,000 or more hours.
Although the common trick with computer front panels seems to have been to just run bulbs under-rated,
e.g. a 6V bulb in a circuit with Vcc=5V, with some further voltage drop in the drive circuit the bulb sees well under 5V.
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