[Prev][Next][Index][Thread]
Who or what is Q
----------
From: W Y Liu [SMTP:eenwyl-at-sun.leeds.ac.uk]
Sent: Saturday, August 22, 1998 10:06 PM
To: tesla-at-pupman-dot-com
Subject: Re: Who or what is Q
Given that there is an oscillator of Q=100, the time constant
of the turn-on transient for this oscillator is roughly 100
cycles of the oscillation frequency in length.
Louis
(non-coiler)
> From tesla-request-at-pupman-dot-com Sat Aug 22 22:40 BST 1998
> Resent-Date: Sat, 22 Aug 1998 15:35:48 -0600
> To: "'Tesla List'" <tesla-at-pupman-dot-com>
> Subject: Who or what is Q
> Date: Sat, 22 Aug 1998 16:16:56 -0500
> MIME-Version: 1.0
> Content-Transfer-Encoding: 8bit
> X-MIME-Autoconverted: from quoted-printable to 8bit by pupman.pupman-dot-com id
PAA14566
> Resent-Message-ID: <"O5saW3.0.4g3.qcptr"-at-poodle.pupman-dot-com>
> Resent-From: tesla-at-pupman-dot-com
> X-Mailing-List: <tesla-at-pupman-dot-com> archive/latest/120
> X-Loop: tesla-at-pupman-dot-com
> Resent-Sender: tesla-request-at-pupman-dot-com
> From: Tesla List <tesla-at-pupman-dot-com>
> Original-From: Tesla List <tesla-at-stic-dot-net>
>
>
>
> ----------
> From: RWB355-at-aol-dot-com [SMTP:RWB355-at-aol-dot-com]
> Sent: Saturday, August 22, 1998 12:41 PM
> To: fwd
> Subject: Who or what is Q
>
> Hi all,
>
> There has been a lot of talk about "Q". Let me see if I can shed some light on
> who or what Q is.
> NO Q isnīt that dude from Star Trek.
> Q is a ratio factor that describes the behavior of a circuit. Without running
> a lot of math:
>
> w(omega) * L
> Q= ------------------ Lets simplify this as w=2* pi*F
> R.
> 2*pi*f*L
> = ------------------
> R
>
> So this means Q is the ratio of inductive reactance to (ohmical) resistance.
> The higer your Q is (Read: high inductive part, low resistance part) the
> "sharper" your resonance curve is (if you plot it). A small Q (e.g.=1) would
> give you a lazy curve like an upside down "U". A high Q (e.g. 1000) on the
> other hand would give you a fast rise / fast drop curve with a real needle
> point as the peak value. The "cut-off", if you will, is much harder. Taking
> this and the transformer laws into account you can now see why a high Q coil
> will be able to produce a longer and fatter spark. This also shows why you
> canīt (like I first did, growl!!) just go to wire length calculations for
your
> secondary. A small coil (high h/d ratio) will have a different inductance
than
> a big coil (low h/d ratio) wound with the same length of wire. The big coil
> (using thicker wire) has a better Q, so it will perform better. Of course you
> need to adjust the input power for the bigger coil. The bigger coil will need
> more juice. But if you connect your big ps to the smaller coil you will get
> less output bang for your money. What I find very intersting is that the
> optimal h/d ratio turns out to be Pi (3.14159 etc), but it does make sense if
> you look at several ac equations.
>
> coiler greetings,
> Reinhard
>
>
>