Thanks James for the info!

Regards

Tal Bejerano
AMC - ISRAEL


-----Original Message-----
From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On
Behalf Of James Paul
Sent: Wednesday, June 19, 2002 2:20 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]: Re: toroids and other


 Kooter,

 Generally speaking, it is correct that the space between windings is
 basically a non issue.   What is at issue is the Al value of the material
 you are using, and the frequency range determines the material you will
 use.  There are several materials from which to choose.  I personally use
 Amidon Associates parts for my toroid coils.  I have a flod apart chart
 that has all the specifics on it, but I'm sure if you go to their website,
 you'll be able to find the same thing.

 The general procedure is to ....

 Choose the frequency range of interest...

 Choose the material for that frequency range that will give you the
 inductance value you need

 From the Al value given for that material and the formula (equation)
 given, plug in the values and determine the turns count.

 Wind that many turns on the coil and you're basically done.

 You may have to adjust the wire size to get the "q" that you want or need.
 You may also have to adjust the number of turns by plus or minus a few
 turns to account for stray capacitance and such.   But this is basically
 it.

 Hope it helps you out.


                                              Regards,

                                                Jim


> Hi to all
>
> Are they any basic rules for winding high frequency (100-500Khz) on
> toroids? I am starting building some psus' and the main problem is to
> wind the transformers. I found some info but not all consist, some say
> do like that and others take other approach. I am really confuse, are
> they really basic rules for that or most of it is trial and error?
>
> for example: I measure a small choke that I made with reading of 1mH
> even if I wind it closely or with spaces between the windings the
> reading is the same. that mean it doesn't matter if it closed wind or
> not?
>
>
>
> Regards
>
> Tal Bejerano
> AMC - ISRAEL
>
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