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Active Contributor

Join Date: Dec 2006
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Transformer Design Information Needed

12/08/2006 6:29 AM

I wanted about the information about how to design a transformer

The voltage in our case is 230v and 50 hz.the output we need the secondary voltage 12 volts and current 800milliamphere

So what wiil be the below

1.primary turns and gauge of the primary wire

2.secondary turns and gauge of the secondary wire

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Power-User

Join Date: Nov 2006
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#1

Re: Transformer Design Information Needed

12/08/2006 8:51 AM

I remember from my school boy experience the you need 9 turns per volt for a one square inch core (excuse non SI units) and pro rata. That was of course with core materiel of 1940 but I don't expect things have changed much

Tables can be found on the internet listing the appropriate wire gauge for the specified currents.

The current in the primary winding will be approximately the voltage ratio times the secondary current i.e 0.8*(12/230)

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Guru
Engineering Fields - Control Engineering - New Member China - Member - New Member

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#2

Re: Transformer Design Information Needed

12/08/2006 9:11 PM

Thats easy things, but you have to know your core's flux density. then youi can get the turns. If you dont know it, yhou will get wrong turn and the transforer will be burned. Syhprom is not quiet right, because he ingore the B value. This tranfermer is cheaper here, I can offer you with regulator. info@ndt.cn

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Power-User

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#3
In reply to #2

Re: Transformer Design Information Needed

12/09/2006 6:14 AM

I did in fact state that the core materiel was what was available in 1940 when I was a school boy, I doubt that things have changed much over the years

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#10
In reply to #3

Re: Transformer Design Information Needed

12/09/2006 11:59 PM

thanks for your reply

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Participant

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#12
In reply to #10

Re: Transformer Design Information Needed

12/11/2006 9:48 PM

The relationship below might help you in designing a transformer:

Np/Ns=Ep/Es=Is/Ip

where: N - no. of turns

E - Voltage

I - current

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Guru
Engineering Fields - Control Engineering - New Member China - Member - New Member

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#4

Re: Transformer Design Information Needed

12/09/2006 8:06 AM

Hi, sym you are not quite wrong, of cuase not quite right. thoery formula doesnt change any more since Farad times. Maybe there was very little soft magnetic material for transfermer. Today the silicon steel can be from 0.8T to 1.8T. sot that you will have 2.3 time difference turns. Generally we can use it as 1.2T for our counting.Of cuas different area has different turns as well. The formulas would be: V=4.44xSxBxfxexp(-4) where v=voltage V s= area cm^2 B= flux T f= frequency Hz ok you can use this for your transformer making.

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Power-User

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#5
In reply to #4

Re: Transformer Design Information Needed

12/09/2006 9:24 AM

"9 turns per volt for a one square inch core (excuse non SI units) and pro rata. "

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Commentator

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#6

Re: Transformer Design Information Needed

12/09/2006 11:00 AM

Primary winding 230 V 44 mA 2480 turns wire diam 0.15 mm Secondary winding 12 V 800 mA 136 turns wire diam 0.5 mm FeSi Core 20 x 20 mm

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Power-User

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#7
In reply to #6

Re: Transformer Design Information Needed

12/09/2006 11:25 AM

Is that for 50 or 60 HZ ? the fluz density is about 28% higher than my calculation if it is 50HZ but core materials may have improved over the years.

I am hunting for a small un-potted transformer to take some measurements.

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Power-User

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#8
In reply to #7

Re: Transformer Design Information Needed

12/09/2006 11:32 AM

Without hunting for the cheapest source I find I can buy a transfomer of that spec for $15, I wonder what it would cost to build just one!

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Commentator

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#9
In reply to #7

Re: Transformer Design Information Needed

12/09/2006 10:43 PM

50 Hz

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Anonymous Poster
#11
In reply to #9

Re: Transformer Design Information Needed

12/11/2006 6:24 PM

European Suppliers

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Anonymous Poster
#13

Re: Transformer Design Information Needed

11/01/2007 3:39 PM

check Mitchell Electronics for good information on transformers

they have been around for over 50 years....they mfg in NY

www.yesmec.com

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