ENAMELED CuNi44 0.1mm diameter (Constantan, Isotan) Resistance wire

[ryanj]

Hi all,

Ive got an excessive amount of this wire so if anyone wants any let me know how much in grams, and ill give you a price plus shipping.

Ill even wind it on to a spool.

wire.jpg

Minimum Amount will be 100g, for $23 AUD.

CuNi44, also called Constantan, has a very low temperature coefficient, high electrical resistance, high ductility and non-corroding properties. It is suitable for use at temperatures up to 600°C (1110°F). Is a very malleable, very ductile alloy, it has a very good resistance to oxidation.The alloy is non-magnetic. It is suitable for electrical resistors, potentiometers, heating wires, heating cables and mats.



John Brown from ecdesigns describes how to make virtually inductance and capacitance free resistors in his thread here:

Building the ultimate NOS DAC using TDA1541A

[jameshillj]

ryanj,

What is the resistance per metre and who made it? Isabellenhutte?

... James

[ryanj]

Hi james,

Thanks for asking. The resistance is 65ohms per metre. Made by Wisdom Alloys.

Ryan

[alazira]

Hi Ryan,
What is the length per gram?

[ryanj]

Hi alazira

A rough calculation gives me 14.18 metres per gram.

So your getting about 92k ohms per spool.

Ryan

[alazira]

Hi Ryan,
Package received. Thanks for the bonus. BTW, do you have an estimate of what wattage this wire can handle?

[ryanj]

alazira,

Good to hear the wire arrived.

Not too sure about the power handling of this wire, i remember reading on john browns thread that it was "high wattage". I also remember that a member asked the same question that you asked me, and im pretty sure john provided a calculation in his reply, but i cant for the life of me find where it is, sorry.

Ill keep looking.

Ryan

[ryanj]

Here is something that might help you. Quoted from John Brown.

Honeycomb / Mobius resistor wattage Hi ppap64.

Quote:
If you use 100 ohm/m Isotan to wind them, approx. what wattage
rating would they have?
I use these resistors for passive I/V conversion, dissipation here is approx. 4 milliwatts. Wire is not used for providing high wattage but for achieving low noise levels.

Given a 500R Mobius / Honeycomb resistor made of 100 ohm/m Isotan resistance wire, power rating equals approx. 2.6 watts. This is based on wire temperature of approx. 100 degrees centigrade and 72mA running through the wire.

So a 100R Mobius resistor of the same wire could handle P = I * I * R = 0.072 * 0.072 * 100 = 518 mW.

Wattage can be increased by increasing wire diameter.

Here are indication currents (approx. 100 degrees centigrade wire temp) for different Isotan wire diameters:

0.5mm, (2.5 Ohms / meter), 608 mA
0.25mm, (10 Ohms / meter), 368 mA
0.15mm (28 Ohms / meter), 128 mA
0.1mm, (63 Ohms / meter), 76 mA
0.08mm, (100 Ohms / meter), 72 mA

500 Ohm Honeycomb resistor made from 200 meters of 0.5mm diameter Isotan would have power rating of approx. 184 watts.

[dady]

Hi Ryanj, What is the maximum temperature that support the enamel?
Do you have a seller of this wire?
I am interested in the construction of resistors made with constanta or nichrome. I not sure if i want to do in honey comb maybe making a coil in one sense and the other in the counter sense of the other for cancelate the magnetic field. I have in Argentina, some old resistors bobinated in no magnetic form that i took from old transmision devices from the airforce. Not here in Spain but the need with little inmagination is the mother of the invention.

Best Regards
Esteban

[AndrewT]

Current rating of the resistance wire will be determined by the surface temperature.
Resistance, surface area and environment will control that surface temperature.

Don't get confused by looking at power ratings.