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 ?

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

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/

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.

Uh... Ignoring power factor... Power is power. Law of conservation of
energy, right?

N_Cook wrote in message
...
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/




I'd forgotten about the hook-up wire volts drop, about 145W, 80 volt, 1.8
amps for the lamp. DC that is of course

On Sun, 10 May 2009 19:27:16 +0100, "N_Cook" put
finger to keyboard and composed:

N_Cook wrote in message
...

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

I'd forgotten about the hook-up wire volts drop, about 145W, 80 volt, 1.8
amps for the lamp. DC that is of course

It seems to me that your lamp has a constant voltage characteristic
and that its brightness is determined by a variable current source
within an electronic ballast.

I would think that the arc voltage would be determined by the lamp's
geometry. For example, could it be possible that one maker's 100W lamp
A may be rated for 1A at 100V, whereas another maker's lamp B may be
rated for 1.25A at 80V? If so, then a ballast designed for lamp B when
used with lamp A may try to deliver a constant current of 1.25A,
causing the lamp to dissipate 125W.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Sun, 10 May 2009 19:27:16 +0100, "N_Cook" put
finger to keyboard and composed:

I'd forgotten about the hook-up wire volts drop, about 145W, 80 volt, 1.8
amps for the lamp. DC that is of course

You may like to read "Sam's and Don's D-Lamp FAQ -- Gas Discharge
Lamps, Ballasts, and Fixtures".

Operation of Discharge Lamps on DC:
http://members.misty.com/don/dschlamp.html#dlodld

"... most discharge lamps are only partially compatible with DC, and
some are not compatible at all."

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc Zabkar wrote in message
...
On Sun, 10 May 2009 19:27:16 +0100, "N_Cook" put
finger to keyboard and composed:

N_Cook wrote in message
...

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

I'd forgotten about the hook-up wire volts drop, about 145W, 80 volt, 1.8
amps for the lamp. DC that is of course

It seems to me that your lamp has a constant voltage characteristic
and that its brightness is determined by a variable current source
within an electronic ballast.

I would think that the arc voltage would be determined by the lamp's
geometry. For example, could it be possible that one maker's 100W lamp
A may be rated for 1A at 100V, whereas another maker's lamp B may be
rated for 1.25A at 80V? If so, then a ballast designed for lamp B when
used with lamp A may try to deliver a constant current of 1.25A,
causing the lamp to dissipate 125W.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.


A more complete set of readings for a 2004 Infocus X2

11,600 lux measuring with probe in the output from the lens. 50mm from the
ring,
with no video and white "blank" screen . With A4 sheet illuminated and a
photographic
light level meter, set for 100 ASA gave f4, 1/60 second reading. With
ambient
of 17 deg C.
Using diode temperature probes, the parabolic reflector reached 85 deg C and
88 degree
after switch off. The light tunnel reached 46 deg C. The housing
between thermal switch and over the colourwheel reached 26 deg C
and 47 deg C at switch off.
Normal power use when warmed up 80V, 1.8 amp (measured with 0.1R
in line and hookup wire volts-drop). At first striking then drops to about
20V then increases
to 80V. If still hot when trying to power up
then starts at 1300 volts, drops to 64V with no lamp ,
470V down to 64V etc
until the fans have cooled it down enough.
Menu brightness change makes no
difference to lamp brightness. Changing to low power
setting does drop the light output, but volts
stay at 80 V so presumably current drops, used for lower
fan noise, very large screen display not required.
Blue screen , no signal, low power setting, with thermometer bulb placed
at lower left front where most heat is blown out took 10 minutes
to stabilise at 25 deg C over ambient.


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