Interesting. I can see it dropping due to conduction losses when the voltage gets too low (so that the wire gets too fat) but what's the mechanism for the drop-off at high voltages?
Cheers,
Phil Hobbs
Designing a full range of filament lamps to operate over a wide range of voltages is a challenge rather like trying to solve a set of simultaneous equations when there aren't enough variables, so you end up with compromises, such as lower efficiency.
To make a 240V filament, you need a very long thin wire. It has far too much surface area to get to the 2700K operating temperature without radiating 100W away at a lower temperature. The way 240V filament lamps are made to work is to double coil the filament, so that much of the filament is radiating heat back onto itself, and the effective surface area for radiating heat away from the filament is significantly less than the filament's real surface area. This isn't as effective as using an optimum thickness filament in the first place, i.e. you have just the right surface area to radiate
100W when it's reached 2700K, and you still have a larger surface area for filament evaporation and thinning.And yes, you're right about heat loss by conduction down the lead-in wires becoming increasingly significant at low voltages/high currents. With longer fragile filaments, the loss from the ends is proportionally less, but you may also require filament supports, which are additional routes to lose heat, and you lose more by convection to the gas-fill.
-- Andrew Gabriel [email address is not usable -- followup in the newsgroup]
So all the things you buy are delivered to the stores on bikes?
That's not my call, thank you very much.
Cheers! Rich
Um, uh, hello? So you really think that gasoline prices don't impact your life, just because you personally don't burn the stuff? You don't think the prices of every single thing you buy are influenced heavily by fuel costs? Your world isn't *that* insular, is it?
He doesn't think. That's the problem. As long as he can get his booze, he doesn't care.
-- You can\'t have a sense of humor, if you have no sense!
Gawd, you people sure do make up a lot of stuff. Prices are going up anyway, for any number of reasons; I have no control over that in any case. (Try buying food that used no fuel in the manufacturing.) All I was saying is that I don't buy gasoline.
Are you advocating lobbying for fuelless food delivery? Sorry, I'm not one of those activist fools.
Thanks, Rich
YOU CAN ALL CLEAN MY PROBE
I AM PROTEUS
My dad had one, 150 W i think. It would solder 12 Ga. sheet metal. .
lot-episode
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Oh, but the Russians do have some interesting products
"its for people who like connecting electricity with own fingers"
"there are many curious people trying to get their fingers in plug, and this is an easy way to do it"
and at bottom under the power board "our perfectly designed network port will match group sessions"
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