Electronic load

[mike]

Hello,

the fools are not aware of the dramatic change of resistance between a
cold and hot bulb...

Bye

Maybe the fools just understand what they need and how a light bulb might
be useful in that application.

Sometimes, easy and good enough is just good enough. And the fools
understand that.

 

[Klaus Kragelund]

Maybe the fools just understand what they need and how a light bulb might

be useful in that application.



Sometimes, easy and good enough is just good enough. And the fools

understand that.

When I was I kid, my dad go me introduced (indoctrinated) into electronics.He gave me some switches and 12V bulbs to play with. He then added a large12V bulb in series with the battery, so a short in the succeeding circuit would be quite indicative. Bulbs can sometimes be put to good use

Cheers

Klaus

 

[Uwe Hercksen]

** They should measure the resistance of a cold bulb some time....

Hello,

I did that some years ago and compared it with the resistance computed
from voltage and power of the bulb.

Bye

 

[Phil Allison]

"Klaus Kragelund"

When I was I kid, my dad go me introduced (indoctrinated) into electronics.
He gave me some switches and 12V bulbs to play with. He then added a large
12V bulb in series with the battery, so a short in the succeeding circuit
would be quite indicative. Bulbs can sometimes be put to good use


** 12V auto bulbs are often found in model train speed controllers as
current limiters and overload indicators.

Another use is with tweeters in high power speakers - one or two 12V bulbs
in series protects them from being over powered and damaged.

In both cases it's the fact that bulbs are NOT like resistors that makes
them useful.


.... Phil

 

[Uwe Hercksen]

Maybe the fools just understand what they need and how a light bulb might
be useful in that application.

Sometimes, easy and good enough is just good enough. And the fools
understand that.

Hello,

but do the fools know if the source used is compatible to the high
current flowing through a cold bulb?

Bye

 

[Cydrome Leader]

"Klaus Kragelund"


When I was I kid, my dad go me introduced (indoctrinated) into electronics.
He gave me some switches and 12V bulbs to play with. He then added a large
12V bulb in series with the battery, so a short in the succeeding circuit
would be quite indicative. Bulbs can sometimes be put to good use


** 12V auto bulbs are often found in model train speed controllers as
current limiters and overload indicators.

Another use is with tweeters in high power speakers - one or two 12V bulbs
in series protects them from being over powered and damaged.

I only used gold plated, cryo treated OFHC copper filaments in my tweeter
protecting lamps.

 

[tm]

Hello,

but do the fools know if the source used is compatible to the high current
flowing through a cold bulb?

Bye

Maybe the source is used to power a light bulb?

 

[Jasen Betts]

Any simple way to dump 500Watts fixed @100 volts ? Or is it easier to have
5 x 100R 100Watt resistors and a big heat sink ? test time would be <
1minute...

several metres of nichrome wire, say, a couple of toasters in series

 

[George Herold]

"zed wit"






** Why do so many fools suggest bulbs in place of resistors ??



Incandescent bulbs use tungsten wire that has a strong positive tempco - so

much so that the effective resistance value changes over a ratio of about 12

times from room temp to full brightness.



OTOH, high power resistors use wire that has almost no tempco and the same

goes for heating appliances ( jugs, toasters room heaters etc).

Interesting.. thanks Phil. So do toasters and such use nichrome wire?

I was thinking (erroneously) that since a toaster gets 'red hot', that the resistance of the element would also change a bunch, like tungsten.

I'm going to have to measure a piece... I've got a drawer at home filled with old heating elements.

George H.

 

[Phil Allison]

"George Herold"

Interesting.. thanks Phil. So do toasters and such use nichrome wire?

** Generally - yes.

I was thinking (erroneously) that since a toaster gets 'red hot', that the
resistance of the element would also change a bunch, like tungsten.

** Draw a heap of amps at switch on and blow the fuse - wouldn't it?

Lamps get hot in fraction of a second but heaters do nothing of the sort.

Plus tungsten lamp filaments burn fiercely in air.

I'm going to have to measure a piece... I've got a drawer at home filled
with old heating elements.

** Submersible heating elements may have a small positive tempco - as may
soldering irons.




.... Phil.

 

[Phil Allison]

"John Fields"

Nichrome has about a tenth the tempco of tungsten:

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/rstiv.html

--

** Arrant nonsense.

See table at bottom of this link:

http://en.wikipedia.org/wiki/Nichrome

The actual tempco is slightly non linear and WAAAY less than tungsten or
copper.

Plus 6% at 2000C.

Tungsten is nearly plus 1200 % at the same temp.



.... Phil

 

[George Herold]

---

Yes, though toasters use nichrome "ribbon".

---






---

Nichrome has about a tenth the tempco of tungsten:



http://hyperphysics.phy-astr.gsu.edu/hbase/tables/rstiv.html

Hmm, the numbers for copper and silver look a bit high. I always figure that the temp coef for pure metals should be something like 1/temperature (in degrees K) so something like 0.0033 at 300 K. The numbers on the wiki page look 'better' to me.
http://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
(you've got to scroll down to the table.)

George H.

 

[George Herold]

"John Fields"






** Arrant nonsense.



See table at bottom of this link:



http://en.wikipedia.org/wiki/Nichrome



The actual tempco is slightly non linear and WAAAY less than tungsten or

copper.



Plus 6% at 2000C.

(well F not C... )

But that's pretty neat, it's basically flat from 500 C to 1000 C.
(more fun will be to measure some.)

 

[Phil Allison]

"John Fields is an IDIOT "

** Totally irrelevant.

With that in mind we can say:

Rt = Ro (1 + alpha T)

** Nichrome ( along with other low tempco alloys) does NOT follow that
formula.

The resistance barely changes from room temp to red hot.

http://www.wiretron.com/nicrdat.html

You are using YOUR ERROR in your false proof.

Piss off - you fucking fuckwit.



.... Phil

 

[George Herold]

"John Fields is an IDIOT "







** Totally irrelevant.










** Nichrome ( along with other low tempco alloys) does NOT follow that

formula.



The resistance barely changes from room temp to red hot.



http://www.wiretron.com/nicrdat.html



You are using YOUR ERROR in your false proof.



Piss off - you fucking fuckwit.







... Phil

(sorry for all the double space crap)
JF I gotta go with Phil here. I measured the resistance of a light bulb
a few weeks ago. I didn't get it up the the max voltage, and still R went up by a factor of 8. If nichrome is only 6% that would be sweet.
(I'm thinking of measuring the johnson noise, as we all know a changing source impedance is a pita.) I'll post any nichrome numbers when I get them.
Hey let's not have any yelling. Things have been much more 'civil' on SED lately. It's nice!

George H.

 

[whit3rd]

Any simple way to dump 500Watts fixed @100 volts ? Or is it easier to have

5 x 100R 100Watt resistors and a big heat sink ? test time would be <

1minute...

That's a lot of heat, even for just one minute. The immersible elements
for 5kW/220 V water heaters are about 20 ohms (two elements per
appliance, Vsquared/R = 2500W).

So your high-power resistor is an item that can be found two at a time
in old scrapped hot water heaters. Any plumber can unbolt a few
before his next visit to a recycler. A flow of water, or a bucket of water, should
cool it well enough.

 

[Phil Allison]

"John Fields is a FUCKING IDIOT "

** And 1100 is not 3000.

What you've done is to look at the 6% increase for nichrome from 20C
to about 1100C, while claiming an increase for tungsten of 1200% over
the same range,

** The real number is more like 700 - 800 %.

Makes no difference to the POINT at all !!!

You CRIMINAL FUCKHEAD !!!!!!!!



** ROTFLMAO !!

"There are none so blind as those who will not see"

The tempco of Nichrome is NOT 0.0004 / C and it is NOT fixed.

The resistance barely changes from room temp to red hot.

http://www.wiretron.com/nicrdat.html

You are using YOUR ERROR in your false proof.

Piss off to HELL - you fucking LYING TWAT.




.... Phil