buschfsu

what give xfos thier impendance values
« on: March 23, 2010, 08:46:17 AM »
i understand turns ratio and sq root of impedance etc.  but what is the difference btw say a 600:600 and a 10K:10K  as they are both 1:1.  is it the amount of turns on the core or the wire size?
PRR said...
OHM'S LAW. Not as an abstract thing: you should be able to glance at a small circuit and "instantly" know I and V, the way a soccer player glances at the ball and knows the angle and kick


kazper

Re: what give xfos thier impendance values
« Reply #1 on: March 23, 2010, 10:47:02 AM »
not that this answers your question but it's a good source of some transformer info.

http://www.radioremembered.org/outimp.htm
http://www.radioremembered.org/xfmr.htm

I'm taking a educated guess here but I believe the wire size is only for your current capability. I think the real difference is going to be the amount of turns. It may be a good thing to look at some of the data CJ has provided as that may be a good clue.
« Last Edit: March 23, 2010, 10:53:03 AM by kazper »
Intentionally left blank

simonsez

Re: what give xfos thier impendance values
« Reply #2 on: March 23, 2010, 11:17:48 AM »
@simonklontz

rodabod

Re: what give xfos thier impendance values
« Reply #3 on: March 23, 2010, 11:30:45 AM »
i understand turns ratio and sq root of impedance etc.  but what is the difference btw say a 600:600 and a 10K:10K  as they are both 1:1.  is it the amount of turns on the core or the wire size?

Generally speaking, inductance and resistance will be higher for the 10K models.

To reflect a 10K impedance back over to your primary, we need relatively high inductance so that the impedance of the primary doesn't drop at low frequencies. So, we can (often) wind extra turns to achieve greater L. The 600 Ohm model doesn't require quite so much, and it is advantageous here to have less coil resistance by using less turns to reduce losses.
Quote from: tv
punchy fat bastard chip

abbey road d enfer

Re: what give xfos thier impendance values
« Reply #4 on: March 26, 2010, 07:54:32 AM »
i understand turns ratio and sq root of impedance etc.  but what is the difference btw say a 600:600 and a 10K:10K  as they are both 1:1.  is it the amount of turns on the core or the wire size?
Inherently, there is nothing like a 600:600 or a 10k:10k xfmr.
In order to qualify as a X ohm winding, the impedance must be significantly higher (typically 5 to 10x) than the rated Z, at the lowest specified frequency.
Let's say you want a 600ohm impedance over an operating range of 20Hz-20kHz.
The impedance is Z = L. 2pi.f
As f is a variable, you need to consider worst case, which is obviously the lowest frequency; so the calculation goes:
L = 600/ 125.6 = 4.77 Henries then you want your 5-10x safety net, which gives roughly
L = 23-47H
The same calculation for a 10k:10k xfmr would give Lp = 40-80H
But in fact, if you restrict the LF -3 dB point to 40 Hz, the same xfmr will be usable as a 20k:20k.
Alternatively, restricting the LF bandwidth allows using less turns for a specified impedance.
Wire size and core size will be dictated by the operating level and the optimization of DCR of windings.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

buschfsu

Re: what give xfos thier impendance values
« Reply #5 on: March 26, 2010, 10:26:21 PM »
interesting so if we were given a total turns count by the mfg could we infer inductance and thus impedance at worst case?
PRR said...
OHM'S LAW. Not as an abstract thing: you should be able to glance at a small circuit and "instantly" know I and V, the way a soccer player glances at the ball and knows the angle and kick

abbey road d enfer

Re: what give xfos thier impendance values
« Reply #6 on: March 27, 2010, 04:22:45 AM »
If you knew the specific inductance Al (in H per sqrtturn), or the relative permittivity, yes.
Permittivity symbol uses the  greek letter mu (micro), relative permittivity is mu index r.
If you know the Al, it's easy, L = Al. n²
If you know the relative permittivity, you must use one of the formulas you can find on the web to calculate the non-cored inductance, and then multiply it by mu index r.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


 

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