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 >>> http://www.chookfest.net/nova3/ledmod.html >>> 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.
