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winding your own transformer


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From:  David [SMTP:davmckin-at-ix-dot-netcom-dot-com]
Sent:  Wednesday, March 04, 1998 3:48 AM
To:  Tesla List
Subject:  Re: winding your own transformer

Tesla List wrote:
> 
> ----------
> From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent:  Tuesday, February 03, 1998 2:48 PM
> To:  Tesla List
> Subject:  Re: winding your own transformer
> 
> Question to David on cores:
> 
> > From:  davmckin [SMTP:davmckin-at-ix-dot-netcom-dot-com]
> > Sent:  Tuesday, February 03, 1998 4:04 AM
> > To:  Tesla List
> > Subject:  Re: winding your own transformer
> 
> <snip>
> 
> > The ETD-34 toroidal ferrite core is a Magnetics core
> > part no. P-43434-EC-00/P-43434-EC-XX where
> > XX is the desired core material listed as numbers 20, 21,
> > 22, or 23 - depending on the desired core material.
> >
> > No. 20 - AL = 135
> > No. 21 - AL = 195
> > No. 22 - AL = 285
> > No. 23 - AL = 410
> 
> Q - are those Al values  in nH/t^2  or 10nH/t^2  ?  There seem to be
> two standards used in the industry. I think Amidon use the 10nH
> figure whereas Philips use the nH figure.


The Al values were given in mH/1000 turns (nH/t^2) and were for the
gapped
version of the cores.  Ungapped Al values ranged in the lower 1000's
(approx. 1900 - 3000).  Our company doesn't have any literature to refer
to on Amidon so I'm not sure which version they use.


>     Apart from the obvious difference in permeability between the
> cores quoted, what are the frequency characteristic differences? I am
> guessing that these are the 10nH figures and the cores are ungapped.
> 

The frequency ranges for these are typically 25kHz to 200-400 kHz,
depending on which material is used and the flux density.  The listings
above are all for the same material (magnetics P material) but with
varying gaps.  ue for these cores ranged from 65 to 259 respectively.
I listed the gapped versions due to the fact they were being used in a
push-pull configuration power supply (to compensate for the DC).


> ?
> Thanks,
> Malcolm
> <snip>


David L. McKinnon