Using a thin wire instead of a resistor?

J

John Doe

Guest
Recently in a non-electronics group, I heard mention of using a thin
wire for resistance and a high current, low-voltage application
(roughly maybe a few amps at about six volts).

What about using a thin wire in place of a resistor?

I guess some resistors are made from a thin, coiled wire, but they
are insulated.

Thank-you.





--
I can measure the resistance through a thin wire, so I know the
resistance.
 
high current, low-voltage application...
What about using a thin wire in place of a resistor?
John Doe
Click to expand...
It's possible--of course that's the same way they make fuses.
A longer, fatter wire might be better.
 
"John Doe" <jdoe@usenet.is.the.real.thing> wrote in message
news:Xns95EDA1457567Cwisdomfolly@151.164.30.48...
Recently in a non-electronics group, I heard mention of using a thin
wire for resistance and a high current, low-voltage application
(roughly maybe a few amps at about six volts).

What about using a thin wire in place of a resistor?
Click to expand...
Using thin wire for resistance is common practice.
They are called wirewound resistors and are manufactured by all the leading
resistor manufacturers.


I guess some resistors are made from a thin, coiled wire, but they
are insulated.

Thank-you.





--
I can measure the resistance through a thin wire, so I know the
resistance.
Click to expand...
 
On Sun, 30 Jan 2005 12:21:08 -0000, "R.Lewis"
<h.lewis@connect-2.co.uk> wrote:

Using thin wire for resistance is common practice.
They are called wirewound resistors and are manufactured by all the leading
resistor manufacturers.
Click to expand...
No they ain't.
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
In article <Xns95EDA1457567Cwisdomfolly@151.164.30.48>,
John Doe <jdoe@usenet.is.the.real.thing> wrote:
[...]
What about using a thin wire in place of a resistor?
Click to expand...
It is a great way to make a resistor with a huge surge rating but a bad
temp-co. I've used it a few times. Higher values need impractical
amounts of wire.

BTW: #40 wire is just about 1 Ohm per inch.

--
--
kensmith@rahul.net forging knowledge
 
John Doe wrote:
Recently in a non-electronics group, I heard mention of using a thin
wire for resistance and a high current, low-voltage application
(roughly maybe a few amps at about six volts).

What about using a thin wire in place of a resistor?

I guess some resistors are made from a thin, coiled wire, but they
are insulated.
Click to expand...
It depends on the application- your description makes it sound like you
are after a high current low resistance resistor. There are precision
milliohm high current resistors with 30ppm/oC stability and specially
designed to uniformly diffuse the heat out of the package. A copper wire
has 3900ppm/oC stability and undefined heat removal characteristics,
comparatively a piece of junk.
 
"John Doe" <jdoe@usenet.is.the.real.thing> wrote in message
news:Xns95EDA1457567Cwisdomfolly@151.164.30.48...
Recently in a non-electronics group, I heard mention of using a thin
wire for resistance and a high current, low-voltage application
(roughly maybe a few amps at about six volts).

What about using a thin wire in place of a resistor?

I guess some resistors are made from a thin, coiled wire, but they
are insulated.

Thank-you.





--
I can measure the resistance through a thin wire, so I know the
resistance.
Click to expand...
Ni-Chrome wire was very popular years ago. It has a high resistance, and can
withstand higher currents. I'm not sure where you can get it today. I
remember using "Picture hanging wire" many years ago from the five and dime,
that was probably aluminum wire!
 
On Sun, 30 Jan 2005 12:46:31 -0500, SCADA wrote:
"John Doe" <jdoe@usenet.is.the.real.thing> wrote in message
....
I can measure the resistance through a thin wire, so I know the
resistance.

Ni-Chrome wire was very popular years ago. It has a high resistance, and can
withstand higher currents. I'm not sure where you can get it today. I
remember using "Picture hanging wire" many years ago from the five and dime,
that was probably aluminum wire!
Click to expand...
http://www.google.com/search?q=nichrome+wire :)

I picked up some on ebay once, surprisingly cheap. :)

Cheers!
Rich
 
On Sun, 30 Jan 2005 13:56:36 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Sun, 30 Jan 2005 16:56:25 +0000 (UTC), the renowned
kensmith@green.rahul.net (Ken Smith) wrote:

In article <Xns95EDA1457567Cwisdomfolly@151.164.30.48>,
John Doe <jdoe@usenet.is.the.real.thing> wrote:
[...]
What about using a thin wire in place of a resistor?

It is a great way to make a resistor with a huge surge rating but a bad
temp-co.

The tempco is pretty good if you use manganin wire, and not so bad
with Constantan wire. Brass is not as bad as copper either.
Click to expand...
I've been trying to find some decent data on the tempcos of Manganin,
Constantan and Nikrothal LX (or any other low TCR material) for a
while now - preferably a typical resistance vs temperature curve, but
the best I've been able to Google is that Manganin is either 10 or
15ppm/K, Constantan is either 20 or 74ppm/K (but over a wider range),
and Nikrothal LX may be 10 ppm/K - not quite enough consistency to
give me any confidence at all. Any chance you can point me to some
credible data (ideally over the range -40C to +60C)? Even better, a
trusted supplier? in Australia?

Tony (remove the "_" to reply by email)
 
Tony wrote:

I've been trying to find some decent data on the tempcos of Manganin,
Constantan and Nikrothal LX
Click to expand...
According to Tennent the Invaluable (1989 edition)

Constantan + or - 4 x 10e-5
Manganin + or - 1 x 10e-5

Paul Burke
 
For limited temperature range, and low self-heating, I've found that
1/4" copper pipe worked just ducky for a 300Amp shunt.

(For a golf cart motor controller :)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Tue, 01 Feb 2005 00:15:49 +1000, Tony <tony_roe@tpg.com.au> wrote:

On Sun, 30 Jan 2005 13:56:36 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Sun, 30 Jan 2005 16:56:25 +0000 (UTC), the renowned
kensmith@green.rahul.net (Ken Smith) wrote:

In article <Xns95EDA1457567Cwisdomfolly@151.164.30.48>,
John Doe <jdoe@usenet.is.the.real.thing> wrote:
[...]
What about using a thin wire in place of a resistor?

It is a great way to make a resistor with a huge surge rating but a bad
temp-co.

The tempco is pretty good if you use manganin wire, and not so bad
with Constantan wire. Brass is not as bad as copper either.

I've been trying to find some decent data on the tempcos of Manganin,
Constantan and Nikrothal LX (or any other low TCR material) for a
while now - preferably a typical resistance vs temperature curve, but
the best I've been able to Google is that Manganin is either 10 or
15ppm/K, Constantan is either 20 or 74ppm/K (but over a wider range),
and Nikrothal LX may be 10 ppm/K - not quite enough consistency to
give me any confidence at all. Any chance you can point me to some
credible data (ideally over the range -40C to +60C)? Even better, a
trusted supplier? in Australia?

Tony (remove the "_" to reply by email)
Click to expand...
Manganin has a parabolic curve of resistance vs temperature, peaking
at some temperature and falling off above or below. Within maybe 10
deg C of the peak, tc is only a few PPM. The peak temp depends on the
manganese composition and on the alloy's history - mechanical
stresses, like winding or fabrication, mess up the curve, and
annealing fixes it. You can buy "wire" manganin with zero tc (parabola
peak) near 25C, or "shunt" manganin with min tc around 80 c or
something, for big shunts that self-heat a lot. One alloy is "manganin
13" (13% manganese) and one is "manganin 12" but I can't remember
which is which.

I can post some data and curves to a.b.s.e. if anybody's interested. I
have that stuff at work.

John
 
On Tue, 01 Feb 2005 19:20:01 +1000, Tony <tony_roe@tpg.com.au> wrote:

Many thanks to Spehro, Paul and John - it's always comforting to come
back here after a fruitless Google session.

And John - I'd certainly appreciate any curves on a.b.s.e if you are
able.

I understood that there were a number of grades of each, but it seemed
I could find compositions and occasionally limited TCR info, but never
together. The apparent effect of annealing isn't surprising; it
shouldn't be hard for us to anneal a batch at a time before assembly.
Click to expand...
I just posted a .pdf of some generic electrical resistance alloy
properties to a.b.s.e., hopefully John can provide his specific data
also.
 
On Sat, 29 Jan 2005 21:51:10 GMT, John Doe
<jdoe@usenet.is.the.real.thing> wrote:

Recently in a non-electronics group, I heard mention of using a thin
wire for resistance and a high current, low-voltage application
(roughly maybe a few amps at about six volts).

What about using a thin wire in place of a resistor?
Click to expand...
One of Bob Pease's colums was about doing this (well, thicker wires
for a very low resistance). He made a round squirrelcage thing
(distributes the current to each wire equally) of wire with the wires
far enough apart so each wire doesn't heat up much, so the value
doesn't change much.
Here's the article:
http://www.elecdesign.com/Articles/ArticleID/2144/2144.html

I guess some resistors are made from a thin, coiled wire, but they
are insulated.

Thank-you.
Click to expand...
-----
http://mindspring.com/~benbradley
 
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