High Frequncy Coil Driving

Discussion in 'General Electronics Chat' started by bte, May 31, 2013.

  1. bte

    Thread Starter New Member

    Aug 15, 2012
    8
    0
    Hello,

    I have a hypothetical question:

    If I'm driving a coil at a high frequency, around 50Mhz, with a coil inductance of around 500uH, from a distance about about 10 feet from switch to coil, do you need a transmission line or are you better off without one for driving an inductive load?

    Thanks!
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,157
    1,795
    I don't understand the motivation for the question. What is the purpose of creating a 50 MHz signal with an inductor for a load? What purpose do you think will be served by using or not using a transmission line?
     
  3. bte

    Thread Starter New Member

    Aug 15, 2012
    8
    0
    I want to make sure the pulse doesn't just reflect back, but gets used by the coil.
     
  4. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi,

    To avoid reflections; use coax cable, or twist pair cable. For that frequency and line length you must terminate the line with its characteristic impedance. The source impedance should also match. You can use a matching transformer, or resistor pad if required.

    My guess is you can just place the 500uH coil across the terminating resistor. The coil impedance is very high at that frequency, but a lot depends on details you have not provided.

    Good Luck,
    Ifixit
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,157
    1,795
    So the problem of the terminating resistor is that it will dissipate real power. You could also come up with a capacitor in series or parallel that would match the characteristic impedance of the transmission line. How much power do you want to deliver to the coil and for what purpose?
     
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