Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....
--
EA

On 3/12/2011 8:27 PM, Existential Angst wrote:
Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....

It's a curve, showing variable resistance.

It's a curve, showing variable resistance.

Or should I say, varying resistance, as the incandescant lamp is a
non-linear resistor.

On Sat, 12 Mar 2011 04:27:19 -0500, "Existential Angst"
wrote:

Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....

http://imageupload.org/?di=712999347565

http://imageupload.org/?di=8129993475615

Jim

Hmm. My Dad has a Variac, wonder if he'd loan it to me?

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Existential Angst" wrote in message
...
Awl --

Inyone have data (or a link), or feel like doing the
'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac....
goodgawd....
--
EA

On Mar 12, 3:27*am, "Existential Angst" wrote:
Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? * AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... * *goodgawd.....
--
EA

http://preview.tinyurl.com/4w8lv48

On Mar 12, 4:27*am, "Existential Angst" wrote:
Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? * AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... * *goodgawd.....
--
EA

Guess that means me, most everyone else I know would rather argue than
measure.
http://en.wikipedia.org/wiki/Aristotle

60W bulb, analog clamp-on ammeter with 10X range extender, HF
voltmeter calibrated at 12.000VDC. I set the current to the major tick
marks to squeeze maximum accuracy from the analog scale.
, , , , .

The filament takes about half a second to stabilize at each new
temperature.

jsw

On Mar 12, 8:50*am, Jim Wilkins wrote:
, , , , .

I see bogus Email address masking, so:
3.1V at 0.1A, 20.5V/0.2A, 46.4V/0.3A, 82.3V/0.4A, 127.2V/0.5A.

jsw

On Sat, 12 Mar 2011 04:27:19 -0500, "Existential Angst"
wrote:

Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....

Per Fink's "Standard Handbook for Electrical Engineers":

(amps/AMPS) = (volts/VOLTS)^t
where t=.541 for gas-filled lamps and t=.580 for evacuated lamps.

Figure 26-7 in the 12th edition also shows this and other
relationships in graphical form. Fink references "LD-1 Lamp Bulletin,"
GE, 1946, by CE Weitz.

--
Ned Simmons

wrote:
...
http://imageupload.org/?di=712999347565
...

That chart shows voltage vs. current. I.e., current on the x
(horizontal) axis and voltage on the y (vertical). Through all my
engineering schooling and my own graphing, the x axis is the independent
variable and the y is the dependent one.

So, is the grapher in the linked chart really thinking about how the
voltage varies as the current changes? Or is he/she just an
ass-backwards grapher? Either way it seems ass-backwards to me.

Whenever I see this (switched independent and dependent variables) I
find it confusing and (hence) irritating. Yeah, I know, I'm
obsessive-compulsive.

Rant off,
Bob

BTW - while I'm ranting, let me get this off my chest: why does
Thunderbird have such a ****ty spell checker? When it gives you a list
of suggested replacements, it often avoids the obvious; it doesn't
automatically accept the plural of singular words that it knows; and its
model for capitalization is screwy. Is this their little joke against
the obsessive-compulsives amongst us?

On Mar 12, 9:37*am, Ned Simmons wrote:
On Sat, 12 Mar 2011 04:27:19 -0500, "Existential Angst"

wrote:
Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? * AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... * *goodgawd.....

Per Fink's "Standard Handbook for Electrical Engineers":

(amps/AMPS) = (volts/VOLTS)^t
where t=.541 for gas-filled lamps and t=.580 for evacuated lamps.

Figure 26-7 in the 12th edition also shows this and other
relationships in graphical form. Fink references "LD-1 Lamp Bulletin,"
GE, 1946, by CE Weitz.

--
Ned Simmons

Energy in equals energy out.
Black-body radiant heat loss:
http://hyperphysics.phy-astr.gsu.edu...mo/stefan.html
I don't know how much the Argon transfers by conduction and
convection, or how closely they control the gas pressure. That "60W"
bulb which I use for a battery+inverter test load shows 55W on a KAW
at 120V.

jsw

Funny my DNS server shows this as a dead link.

----------------------
"Bob Engelhardt" wrote in message ...
That chart shows voltage vs. current. I.e., current on the x
(horizontal) axis and voltage on the y (vertical). Through all my
engineering schooling and my own graphing, the x axis is the independent
variable and the y is the dependent one.

So, is the grapher in the linked chart really thinking about how the
voltage varies as the current changes? Or is he/she just an
ass-backwards grapher? Either way it seems ass-backwards to me.

Whenever I see this (switched independent and dependent variables) I
find it confusing and (hence) irritating. Yeah, I know, I'm
obsessive-compulsive.

Rant off,
Bob

BTW - while I'm ranting, let me get this off my chest: why does
Thunderbird have such a ****ty spell checker? When it gives you a list
of suggested replacements, it often avoids the obvious; it doesn't
automatically accept the plural of singular words that it knows; and its
model for capitalization is screwy. Is this their little joke against
the obsessive-compulsives amongst us?


wrote:

http://imageupload.org/?di=712999347565

Careful. Variacs are known waveform distorters. The government would not let
us use them for precision power measurements as the waveform adopts many
harmonics in some units.

This could drive your accuracy of power testing around the bend is you want
more than one digit of accuracy. Multiply a distorted current waveform
measurement times a distorted voltage measurement (from the same voltage
source) and you can get power than is 10-20% in error very quickly.

---------------------
"Existential Angst" wrote in message
...

Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....
--
EA

On 3/12/2011 1:27 AM, Existential Angst wrote:
Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....

all this information is available, in detail, for a large variety of
bulbs in the GE lamp handbook, among other places. The lamp is a highly
non-linear resistance element - in the incadescent region it
approximates a constant current device well enough to be used in some
ballast applications

--
www.wbnoble.com

Josepi wrote:

Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

Thanks,
Rich

On Mar 12, 5:23*pm, Rich Grise wrote:
Josepi wrote:
Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

Thanks,
Rich

A highly capacitive load, such as a light bulb filament.

A highly capacitive load, such as a light bulb filament.

Jim

Hunh?

Bob AZ

Rich Grise wrote:
Josepi wrote:

Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

Thanks,
Rich

And while youre at it you should tell him that the word
Variac is a registered trade mark. :-)
...lew...

Josepi wrote:

Funny my DNS server shows this as a dead link.


Then you need a better DNS server.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

On 2011-03-12, Josepi J.R.M wrote:
wrote:

http://imageupload.org/?di=712999347565

Funny my DNS server shows this as a dead link.

I find that I have it blocked -- because of spam and attacks
against the sshd port. It is in Bahrain, FWIW. Why choose that as an
image server? I'm not going to unblock it just to see these images.

----------------------
"Bob Engelhardt" wrote in message ...
That chart shows voltage vs. current. I.e., current on the x
(horizontal) axis and voltage on the y (vertical). Through all my
engineering schooling and my own graphing, the x axis is the independent
variable and the y is the dependent one.

So, is the grapher in the linked chart really thinking about how the
voltage varies as the current changes? Or is he/she just an
ass-backwards grapher? Either way it seems ass-backwards to me.

Well -- diode junctions are typically graphed as voltage across
vs current applied -- because the curve gets *very* steep if you are
varying the voltage applied instead.

This may be so done with the lamp filament because of similar
constraints.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Mar 12, 7:56*pm, "DoN. Nichols" wrote:
"Bob Engelhardt" *wrote in ....
That chart shows voltage vs. current. *I.e., current on the x
(horizontal) axis and voltage on the y (vertical). *Through all my
engineering schooling and my own graphing, the x axis is the independent
variable and the y is the dependent one.

So, is the grapher in the linked chart really thinking about how the
voltage varies as the current changes? *Or is he/she just an
ass-backwards grapher? *Either way it seems ass-backwards to me.

* * * * Well -- diode junctions are typically graphed as voltage across
vs current applied -- because the curve gets *very* steep if you are
varying the voltage applied instead.

* * * * This may be so done with the lamp filament because of similar
constraints.

* * * * Enjoy,
* * * * * * * * DoN.

When the test equipment can control either voltage or current it isn't
so obvious which should be the dependent and independent variable.

jsw

On 2011-03-12, Josepi J.R.M wrote:
Careful. Variacs are known waveform distorters. The government would not let
us use them for precision power measurements as the waveform adopts many
harmonics in some units.

Are you *sure* about this? I know that constant voltage
transformers (e.g. the Sola units) do introduce significant waveform
distortion, but a Variac (adjustable autotransformer) is simply a
toroid transformer which should not introduce distortion as long as the
input voltage is not significantly in excess of the design voltage, and
the frequency is near the design frequency. (E.g. I would not use a
400 Hz Variac which I have for 60 Hz operation.)

Now -- I guess that intermittent contact at the wiper might
cause some tiny distortion, but nothing like what a Sola CV transformer
(or similar) produces.

This could drive your accuracy of power testing around the bend is you want
more than one digit of accuracy. Multiply a distorted current waveform
measurement times a distorted voltage measurement (from the same voltage
source) and you can get power than is 10-20% in error very quickly.

So -- if you don't trust a Variac -- how would you trust a
multi-tapped transformer and a switch for producing the varied voltage?

Of course -- the RMS voltage applied should produce the same
result as DC -- assuming that the filament's thermal inertia is
sufficient to keep it from following the AC waveform. If it is changing
temperature that quickly, you have a more serious source of distortion
in the varying load from the filament than I would expect from a Variac
or other variable autotransformer.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2011-03-12, Jim Wilkins wrote:
On Mar 12, 5:23*pm, Rich Grise wrote:
Josepi wrote:
Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

[ ... ]

A highly capacitive load, such as a light bulb filament.

Is this a troll?

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Mar 12, 8:14*pm, "DoN. Nichols" wrote:
On 2011-03-12, Jim Wilkins wrote:

On Mar 12, 5:23 pm, Rich Grise wrote:
Josepi wrote:
Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

* * * * [ ... ]

A highly capacitive load, such as a light bulb filament.

* * * * Is this a troll?

Bait for one.

On Mar 12, 2:02*pm, "Josepi" wrote:
Careful. Variacs are known waveform distorters. The government would not let
us use them for precision power measurements as the waveform adopts many
harmonics in some units.


Which brings up a couple of points. The temperature of the filament
in vacuum tubes does vary if you have AC applied to it. So you will
get some distortion from that. But most of the better DVM's are true
RMS meters, at least on Voltage. I would suspect they would also
measure true RMS current. But does anyone know for sure?

Dan

On Mar 12, 9:05*pm, " wrote:
On Mar 12, 2:02*pm, "Josepi" wrote:

Careful. Variacs are known waveform distorters. The government would not let
us use them for precision power measurements as the waveform adopts many
harmonics in some units.

Which brings up a couple of points. *The temperature of the filament
in vacuum tubes does vary if you have AC applied to it. *So you will
get some distortion from that. *But most of the better DVM's are true
RMS meters, at least on Voltage. * I would suspect they would also
measure true RMS current. *But does anyone know for sure?

* * * * * * * * * * * * * * * * * * * * * * * *Dan

This says they do:
http://www.newportelect.com/manuals/ACGUIDE.htm

I think the RMS converter is after the current shunt that turns
current into voltage.

jsw

We got it from Measurement Canada. They issue documents approving or
disapproving devices for energy metering inspection.

Variacs can have distortion in the laminations...usually slots for some
reason (heat expansion?) that cause the output waveform to have some ringing
in it. I haven't done any scoping or analysis personally and am paraphrasing
NBS information.. Electrical utility meter testboards are frequently
rejected for usage by Measurement Canada for use of Variacs in their
potential and current supplies. I believe some types may pass depending on
the core shape and configuration.

Any transformer with irregular shaped laminations can cause this. They
usually appear as slots for expansion between the E and I laminations or
mounting holes.

-----------------------
"Rich Grise" wrote in message
...
Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

Thanks,
Rich

------------------

Josepi wrote:
Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

In the case of a filament it should be totally resistive and cause no
distortion or phase shift on it's own but RMS amperes x RMS voltage is not
always accurate for power measurements with distorted waveforms.

Yes, most good DVMs, these days, measure a reasonably accurate form of RMS
with various methods.
As Jim's posts says the current is usually measured via a shunt resistance
IR drop.

---------
wrote in message
...
Which brings up a couple of points. The temperature of the filament
in vacuum tubes does vary if you have AC applied to it. So you will
get some distortion from that. But most of the better DVM's are true
RMS meters, at least on Voltage. I would suspect they would also
measure true RMS current. But does anyone know for sure?

Dan


On Mar 12, 2:02 pm, "Josepi" wrote:
Careful. Variacs are known waveform distorters. The government would not let
us use them for precision power measurements as the waveform adopts many
harmonics in some units.

The issue is at cold or hot state ? I don't think
you know they draw 10x on warmup and then at incandescent
temp it comes to the rated wattage.

I find it hard to believe that a VOM doesn't have a current
selection. Older ones didn't have A-C.

So what is the deal - why - and what is the argument....

Martin


On 3/12/2011 3:27 AM, Existential Angst wrote:
Awl --

Inyone have data (or a link), or feel like doing the 'speriment?
25, 50, 75, 100, 120, 125, 150 V? AC and DC?
60 W, 100 W buhbs?

Can't find a VOM with an ammeter, lent out my variac.... goodgawd....

DoN. Nichols wrote:
...
Well -- diode junctions are typically graphed as voltage across
vs current applied -- because the curve gets *very* steep if you are
varying the voltage applied instead.
....

So it's a matter of the aspect ratio of the graph: they'd rather have a
wide & short graph than a narrow & tall one? But that doesn't make
sense - you can have any aspect ratio you want by changing the scales.

And it isn't so much the setup used to determine the graph (e.g.,
varying the voltage & measuring current), as the *function* represented
by the graph. I.e., how one thinks of the device represented. You can
think of a resistor as a device that has a voltage across it as a
function of the current through it. Or as a device that "allows" a
current as a function of the voltage across it. Both are legitimate,
but for a non-linear resistor like a light bulb, I can understand it
more easily if the graph shows current as a function of voltage.

I suspect that for the diode-junction function, current IS the
independent variable. I.e., the current is determined by other factors
and one finds the junction voltage as a function of that current.

Bob

Many years ago I had the delight in learning how RF ammeters worked.
It was a panel meter 0-5 amps. Normal DC shunts could do it for DC,
but for AC ? and RF ?

There was a four terminal 'tube'. There was a heater and a
thermocouple. The meter was measuring the voltage generated by the
thermocouple!

Using this method, any waveform or complex AC riding on or modulated
within an RF signal can be measured.

Martin

On 3/12/2011 8:59 PM, Josepi wrote:
In the case of a filament it should be totally resistive and cause no
distortion or phase shift on it's own but RMS amperes x RMS voltage is
not always accurate for power measurements with distorted waveforms.

Yes, most good DVMs, these days, measure a reasonably accurate form of
RMS with various methods.
As Jim's posts says the current is usually measured via a shunt
resistance IR drop.

---------
wrote in message
...
Which brings up a couple of points. The temperature of the filament
in vacuum tubes does vary if you have AC applied to it. So you will
get some distortion from that. But most of the better DVM's are true
RMS meters, at least on Voltage. I would suspect they would also
measure true RMS current. But does anyone know for sure?

Dan


On Mar 12, 2:02 pm, "Josepi" wrote:
Careful. Variacs are known waveform distorters. The government would not
let
us use them for precision power measurements as the waveform adopts many
harmonics in some units.

Jim Wilkins wrote:
On Mar 12, 5:23*pm, Rich Grise wrote:
Josepi wrote:
Careful. Variacs are known waveform distorters. The government would
not let us use them for precision power measurements as the waveform
adopts many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

A highly capacitive load, such as a light bulb filament.

Huh? Where's the capacitance in a filament?

You need to go to the library and read a basic electricity/electronics book,
or read some basic electricity/electronics tutorials on the internet or
something.

By the way, a triac or SCR lamp dimmer is NOT a variac:
http://www.google.com/images?hl=en&q=define%3Avariac

Good Luck!
Rich

DoN. Nichols wrote:
On 2011-03-12, Jim Wilkins wrote:
On Mar 12, 5:23*pm, Rich Grise wrote:
Josepi wrote:
Careful. Variacs are known waveform distorters. The government would
not let us use them for precision power measurements as the waveform
adopts many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?
[ ... ]
A highly capacitive load, such as a light bulb filament.

Is this a troll?

I'm hoping he's merely uninformed.

Cheers!
Rich

Josepi wrote:
....
Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Oh, yes. And as we all know, governments are infallible fonts of wisdom.
/sarcasm

Thanks,
Rich

Lewis Hartswick wrote:
Rich Grise wrote:
Josepi wrote:

Careful. Variacs are known waveform distorters. The government would not
let us use them for precision power measurements as the waveform adopts
many harmonics in some units.

Where do you get this information? A variac is nothing but an adjustable
autotransformer - what part introduces the distortion?

And while your'e at it you should tell him that the word
Variac is a registered trade mark. :-)

Yabbut, so are Kleenex, Windex, and Drano.

Dunno about Raisin Bran, however. ;-D

Cheers!
Rich

DoN. Nichols wrote:
On 2011-03-12, Josepi J.R.M wrote:
wrote:

http://imageupload.org/?di=712999347565

Funny my DNS server shows this as a dead link.

I find that I have it blocked -- because of spam and attacks
against the sshd port. It is in Bahrain, FWIW. Why choose that as an
image server? I'm not going to unblock it just to see these images.

What about that "dropbox" thingie? I use alt.binaries.schematics.eletronic ;
usually the folks who hang out there are pretty tolerant of off-topic
images, especially if they're kewl. ;-)

Plus, every proper ISP I've had has offered some kind of "personal web
space," where you can post a personal web page, and usually have room to
put up some images, e.g.:
http://mysite.verizon.net/richgrise/images/Me+Gals1.jpg

Cheers!
Rich

Bob Engelhardt wrote:
DoN. Nichols wrote:
...
Well -- diode junctions are typically graphed as voltage across
vs current applied -- because the curve gets *very* steep if you are
varying the voltage applied instead.

So it's a matter of the aspect ratio of the graph: they'd rather have a
wide & short graph than a narrow & tall one? But that doesn't make
sense - you can have any aspect ratio you want by changing the scales.

No, it's because it's hard to control the voltage with enough precision
to get good resolution on the V/I curve.

Hope This Helps!
Rich

As pointed out by others, the incandescent is close enough to being an
ideal resistor in the steady state, but has a big inrush current.

When we worry about Voltage vs current is in a florescent. That curve
looks like a mountain range. In order to make steps in brightness, I
drive with an AC current source and a slow feed back loop with an opto
diode.

On Mar 13, 2:39*am, Rich Grise wrote:
....
I'm hoping he's merely uninformed.

Cheers!
Rich

Your sarcasm filter needs cleaning.

jsw

On Mar 13, 7:16*am, wrote:
...
However at high flux densities, as the magnetising current
aproaches *its peak, *the permeablity decreases. This results in
a spiky non sinusoidal magnetising current (3rd harmonic
distortion).

The turns ratio of the Variac or transformer is unaltered so, *if
the primary primary resistance is zero, *the output waveform will
remain a true sinusoid.

Jim

I don't have the equipment to measure distortion. This is the
magnetizing current and power factor as measured by a KillAWatt for a
20A Variac fed from the end (120V) and voltage boost (140V) taps.

120V: 0.10A, PF=0.58
140V: 0.13A, PF=0.51

I've seen the waveform distort under load when the output is turned
above 120V in the boost configuration.

jsw