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Four Resistance Coils (5k ohm) - non-inductive

Discussion in 'General Electronics Discussion' started by snowbird, May 7, 2013.

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  1. snowbird

    snowbird

    3
    0
    May 7, 2013
    Hi All,

    I am trying to find where I could get at four resistance coils (5k ohm) non-inductive for a hobby project. Any ideas where I maybe able to find these?

    Thanks,
    Dave
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
    2,809
    Jan 21, 2010
    Well... coils are inductive (although there are special non-inductive wirewound resistors).

    The question is: "What do you want these for?". If you can answer that fully, we may be able to point you in the direction of something suitable.

    The main things we're interested in are the power dissipation requirements, and the tolerance required (i.e. is 4.7k close enough).

    Is there a particular reason why you want a coil?
     
  3. snowbird

    snowbird

    3
    0
    May 7, 2013
    Hi Steve,

    Thanks for the reply! The old-style circuit calls for coils, so I'd prefer to stay with what it calls for. Yep..something like 4.7k may be close enough.

    I have seen some 5k coils on India-based web sites, but they seem to be focused on bulk orders. I sent several inquires, but haven't gotten any satisfactory replies from them.

    Thanks for your help with this!
    Dave
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
    2,809
    Jan 21, 2010
    OK, glad that was some help.

    What is the power dissipation?

    And, again, what's this for? Is it a restoration project (where you want the original appearance) or are you trying to stay close to some specifications in an (old) design because you don't understand enough to be confident of choosing suitable alternate parts?

    If it's the first case (restoration) then a common approach is to leave something in place which has the look of the original component (say a huge metal clad electrolytic capacitor) but hide a modern component somewhere (a small modern electrolytic inside the gutted case of the original unit).

    Whilst it is difficult to hide something in an open coil. if it is wrapped around some sort of former, perhaps a modern resistor could hide inside this.

    If it is the latter (you not confident to choose an alternate part) then posting the schematic and/or a link to whatever information you have would be the best step.

    There are many people here who could look at the circuit and calculate the approximate power dissipation of the resistor and subsequently recommend an easier to get modern alternative.
     
  5. snowbird

    snowbird

    3
    0
    May 7, 2013
    I was able to get some spec's that may be able to help. Something very thin like 42 swg on a bobbin 1 inch in diameter and 1/2 inch wide with a resistance of 5000 ohms.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
    2,809
    Jan 21, 2010
    No, sorry, that doesn't help unless the information that if made out of copper wire, it would require just a little over 2.347km of wire (about 1.5 miles).

    That would be 14,709 turns and would be about 144metres in length.

    It would also be highly inductive.

    Your coil would only be comprised of about 125 turns ans be about 2 metres of wire -- so it's not copper.

    Perhaps you can look at my last post and answer the questions I asked. It may yield a solution. I do ask them for a reason.
     
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