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Old 31st May 2007, 09:56 PM   #1
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Default homemade resistors

OK so a pretty simple question but I do need to confirm my thoughts please chaps...
I'm making some low ohmic resistors for my speakers and dont wat to have them inductive...
I have some nichrome wire and instead of spooling it I was going to 'snake' it between some pins....... is this non inductive?

Thanks people
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Old 31st May 2007, 10:35 PM   #2
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Calculate the length of wire required. Wind half of it onto whatever form you're using clockwise. When you get to the midpoint of the wire, reverse the winding direction (go counterclockwise). The magnetic fields from the two halves of the coil will cancel leaving you with very low inductance.

I_F
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Old 31st May 2007, 10:38 PM   #3
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Quote:
Originally posted by I_Forgot
Calculate the length of wire required. Wind half of it onto whatever form you're using clockwise. When you get to the midpoint of the wire, reverse the winding direction (go counterclockwise). The magnetic fields from the two halves of the coil will cancel leaving you with very low inductance.

I_F
Thank you Sir,, that will make things a lot easier than making up a pin board!
Cheers

Lee
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Old 4th June 2007, 07:48 PM   #4
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Just be sure the windings don't short together - nichrome wire is usually non-insulated. You may end up with a zero ohm resistor if the windings are interleaved..

-Len
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Old 4th June 2007, 09:13 PM   #5
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Quote:
Originally posted by len_scanlan
Just be sure the windings don't short together - nichrome wire is usually non-insulated. You may end up with a zero ohm resistor if the windings are interleaved..

-Len
No problems there, I wound the first half around a plastic bolt (follows the thread) and then shrink wrapped it before the return winding.... then another shrink wrap...works perfectly.

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Old 5th June 2007, 01:43 AM   #6
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Careful of the shrinkwrap if you are having any appreciable temperature rise when the resistor is in use, otherwise you may have a Borg problem (resistance is futile!).

Seriously, if you're going to have any sort of real power going through it, then you might want to consider (say) teflon tape rather than shrinkwrap between the 2 layers.
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Old 7th June 2007, 06:47 PM   #7
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Default Nichrome Wire

Do note that most nichrome wire has a very big temperature co-efficient. While yours may be an allow that does not, you may want to check the resistance vs. temperature before you built it into something. Also note that most nichrome wire cannot be soldered and you have to use nuts and machine screws to attach it to something.
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Old 7th June 2007, 07:34 PM   #8
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Well, I've been listening away for a week now and they work very well.
I only power them with a T-amp into Fullrangers so they are never pushed to even warm. (series resistance to bring up that bass).
I did manage to solder terminals on them by using an initial solder blob then my trusty blow torch attachment on my gas iron .....before I wound them of course.
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