Meat Plow wrote in message
...
On Fri, 8 May 2009 08:45:22 +0100, "N_Cook" wrote:

Is it simply volts x amps?
Taken when? at maximum, when heated up, or on some standard standing
voltage, after start-up?
Would one maker's 100W bulb be the same light and power draw as some
other
maker's 100w ?

Not necessarily. One maker's lamp could draw more current to produce
the same output in lumens. I suppose a simple test could be made to
answer your question if you had an original replacement and a
prospective substitute. But unless you repair these things in volume
the likelihood of having different bulbs to test is slim..

I would say to be safe use the original part. Unless your mind is
wandering and you've asked this question for general knowledge

I measured a projector that has 300W consumption on the mains plate but no
info for the bulb consumption.
Added 0.1R in the supply line to the bulb gives an inferred reading of 2.8
amp and 80V over the lamp after 10 minutes to warm up , so 224 watts seems
about right.

Interesting the brightness setting is just in the DLP chip , not the lamp.
But selecting "low power" option does reduce the light output but with lamp
volts staying at 80V , so presumably current draw is less, (0.1R
disconnected by then). This option for reduced fan noise , if large display
/ high ambient light useage, is not required


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/