Re: How to optimize parameters for making a coil with high-Q?


"Arthur C." <nospam@xxxxxxxxxxxxxxxx> wrote in message
news:485b86ff$0$14348$e4fe514c@xxxxxxxxxxxxxxxxx
I want to make a simple coil (inductor) with a Q value as high as
possible.
Now, I would like to know if there are simple guidelines on how to choose
the parameters to obtain this. Parameters are:

- thickness of the wire
- number of rounds
- length of the coil
- area of cross-section

I understand that a realistic description of a coil involves (at least) a
parallel parasitic capacitance C and a series resistance R.
The resulting Q value would then be Q = (1/R) sqrt (L/C). Is this indeed
the
relevant expression for Q?
If the coil is operated at a frequency of the order 1 MHz, can we assume
for
R just the 'DC' series resistance of the wire, or does it change with
frequency?
And, how can C be calculated?
For inductance L I have found some useful information, but for the others
not yet...


Any suggestions? Thanks for your time,

Arthur C.

Look at his "LC experiments" series at http://www.crystal-radio.eu/
It's a tour-de-force on achieving ridiculously high Q values.


.

Relevant Pages

  • Re: OT Question for Iggy
    ... superconducting magnet with a homogenous cylindrical volume of about 2" ... It's the magnet for a Fourier transform ... For whatever reason Oxford favored small diameter wire and lots of turns, ... which has the effect of making the inductance of the coil very large. ...
    (rec.crafts.metalworking)
  • Re: DiMarzio humbucker in an Ibanez guitar (5 way switch)
    ... and then take the bare and solder it onto a separate ground lug. ... Next - take the red wire and wire it the same as the hot wire on the ... your coil tap) to where the white lead was on the Ibanez. ... some pickups DiMarzio makes have good designs for getting both humbucker and ...
    (alt.guitar)
  • Re: Mercruiser Still Wont Start
    ... 12V to the coil thru contacts in the slave solenoid. ... If you can crank it then you do have power to the system. ... beginning point to see if you have 12v being supplied to the wire lead. ...
    (rec.boats)
  • Re: Intermittent Spark in 1979 Rabbit
    ... Also - there is feed wire to the fuel pump relay, ... to the coil providing as much voltage as the battery has to the coil. ... Remember I said you have a resistor wire that feed the ...
    (rec.autos.makers.vw.watercooled)
  • Bad coil?
    ... Because it's running an electronic ignition, ... large terminal on the alternator (with the thick red wire) reads 12.3v. ... To test the coil, I disconnected the electronic ignition from both the ... To try and improve the lenth of the arc I wired the "+" side straight ...
    (rec.autos.makers.vw.aircooled)