Zero-ohm Resistors

Discussion in 'Ham Radio Discussions' started by K4KYV, Mar 4, 2014.

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  1. KI6LZ

    KI6LZ Ham Member QRZ Page

    E=I*R, what no voltage? If there is current there must be resistance. Moral is that you can have voltage without current but you can't have current without voltage. QED
     
  2. SA6CKE

    SA6CKE Premium Subscriber QRZ Page

    With imaginary loads you can.
     
  3. NL7W

    NL7W Premium Subscriber QRZ Page

    Try Frigid North Company.

    www.frigidn.com

    Their resistor stock is second to nobody!


     
  4. W1GUH

    W1GUH Ham Member QRZ Page

    When I was taking EE 101 (well, at the school I went to it was just "6.01"), Elementary Network Theory, whose textbook had the same name and was written by Bose and Stevens (that just could be why I've NEVER liked Bose products!), we all speculated what would happen if we walked into a Radio Shack or a Lafayette and asked for a "One Amp Current Source."

    When I was taking that course the whole concept of a "current source" completely blew my mind. What? Constant current no matter what? That just "didn't compute."
     
  5. G0BXU

    G0BXU Ham Member QRZ Page

    So, if you can't have something with NO resistance whatsoever, what is the ACTUAL resistance of those items sold as 'Zero Ohms Resistors'?

    If it is, in fact, a figure of say 'n' ohms - then surely it becomes an 'n' ohms resistor............:confused:
     
  6. W1GUH

    W1GUH Ham Member QRZ Page

    I learned about the futility of making small value resistors out of conventional wire back in the day. I ham friend wanted a resistor of a very low value for a meter shunt and I told him I could fashion one out of wire with the Bridge (Good ol' GR 1650!) in the lab at school.

    So I got some magnet wire and started cutting it down to the specified value. That was easy. What I also learned at that time is how the value varied all over the place with temp. So much for making meter shunts with conventional wire!

    And speaking of resistors "back in the day" there was talk that a 20% resistor was guaranteed to be at least 10% off, and a 10% resistor was guaranteed to be at least 5% off. The reasoning was that they were picked after being manufactured and measured. Never actually confirmed if this was true or not.
     
  7. PD0AC

    PD0AC Ham Member QRZ Page

  8. K5TCJ

    K5TCJ Premium Subscriber QRZ Page

    While working on my FT-450 recently, I noticed a few Zero Ohm resistors and couldn't figure out why there was such a thing.
    After reading this thread, I now know.
    the Zed is entertaining AND educational. (or the other way around) :)
     
  9. K8ERV

    K8ERV Ham Member QRZ Page

    I do, just use large enuff (so long enuff) that it doesn't heat much. Bulky, but works.
    And don't forget to use a 4-terminal (Kelvin) connection to the shunt.

    TOM K8ERV Montrose Colo
     
  10. ND8D

    ND8D Ham Member QRZ Page

    I'll chime in here with the rest of the EE and design crowd.

    I did schematics and board design for a broadcast transmitter company, we had 0 ohm resistors everywhere. Used for jumpers and on op-amp buffers in case we needed to add gain.

    Fractional ohm resistors are useful for measuring high amounts of current in a system, you just put your current through and measure the voltage drop across (usually in millivolts).

    I also had to make careful selection of milli-ohm resistors for current shunts, basically highly calibrated staples:
    http://www.mouser.com/ProductDetail/IRC-TT-electronics/OARSXPR005FLF/?qs=h26DkM9IuptRPUQZF2fD9Q==
     
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