Winding Your Own Transformers

tmblack · 21st January 2005, 05:08 PM

Has anyone tried to wind their own power transformers?
I'm considering a 120V to 50VCT transfomer @5A.
I have some EI cores of M4 steel, 1.5" center tougue and 5" long.

Anyone know the proper method to do this?

Regards,

Tom

sss · 21st January 2005, 05:48 PM

few tips

first u gotta find a core that can handle that power (500VA) and got enough space for the windings
most of the time u can use a core taken from 500VA (or more)transformer
also its much easier if u allready got the primmary coil (suited for 120V)
if u got all of the above , winding the secondaries wount be a problem

tmblack · 21st January 2005, 06:53 PM

I already have the core as mentioned above. Not sure how to calculate the maximum VA rating for it but it but I can stack up the laminations(it does have to be square).

I just threw a number for the current but 5Ax50V should only be 250VA, not much for its size.

Tom

sss · 21st January 2005, 07:19 PM

50V @5A ct = 500VA(each secondary 250VA)
or maybe u meam 25-0-25

an oversized core is not so good, u will use longer wires=higher output resistance
if u got no primary coil u gotta calculate the number of turns for 120V operation , i dont remember the formula for this

Stocker · 22nd January 2005, 12:59 AM

Somebody wants you to do this... I found this earlier today...
Roll your own power transformers

Do let us know how it turns out!

jackinnj · 22nd January 2005, 02:42 AM

here;s an article from a magazine which went bust about a decade ago:
http://www.tech-diy.com/rewinding_transformers.htm

Sch3mat1c · 22nd January 2005, 03:35 AM

*Sch3mat1c wonders where Geek is

Lesse, http://geek.scorpiorising.ca/windingtransformers.html seems to be the one.

Your core sounds about right. You want to use a core somewhat oversized so you don't run out of room when you're almost done with the windup.

Too large a core is just a waste of good core material.

Don't worry about resistance. A good transformer will barely get warm. For 5A, you'll want around 16-18AWG copper wire.

Tim

Sch3mat1c · 22nd January 2005, 03:53 AM

Quote:

Originally posted by sss
50V @5A ct = 500VA(each secondary 250VA)
or maybe u meam 25-0-25

CT always means the full voltage winding is split, so 25-0-25 would be accurate. However, given power factor of a capacitor input filter, a 500VA (i.e., 10A RMS) rating may be advisable.

Quote:

if u got no primary coil u gotta calculate the number of turns for 120V operation , i dont remember the formula for this

A book I have gives it as E = F * H * N * A * 4.44 x 10^-8, with E in volts, F in Hz, H in "lines of flux per square inch" (1 tesla ~= 60,000 lines; a good value is 50-80k), N is turns and A in square inches (cross section of the center of the core, which the turns are wrapped around). With some algebra you can find whichever you need.

Looks like you'll need about 300-350 turns for the primary.

Tim

tmblack · 22nd January 2005, 07:53 AM

Gentlemen,

thank you for the assistance. I'll try my best to get something done.

Tom

21st January 2005, 05:08 PM	#1
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	Winding Your Own Transformers Has anyone tried to wind their own power transformers? I'm considering a 120V to 50VCT transfomer @5A. I have some EI cores of M4 steel, 1.5" center tougue and 5" long. Anyone know the proper method to do this? Regards, Tom

22nd January 2005, 12:59 AM	#5
Stocker diyAudio Member Join Date: Dec 2003 Location: Austin	Somebody wants you to do this... I found this earlier today... Roll your own power transformers Do let us know how it turns out! __________________ Jesus loves you.

22nd January 2005, 03:35 AM	#7
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	*Sch3mat1c wonders where Geek is Lesse, http://geek.scorpiorising.ca/windingtransformers.html seems to be the one. Your core sounds about right. You want to use a core somewhat oversized so you don't run out of room when you're almost done with the windup. Too large a core is just a waste of good core material. Don't worry about resistance. A good transformer will barely get warm. For 5A, you'll want around 16-18AWG copper wire. Tim __________________ See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!" "It's all in your head. So follow your head. Don't bother trying to explain it, because there is no explanation. Likewise, disregard any who try to explain it, because they're most likely way off the mark." - Myself

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21st January 2005, 05:48 PM	#2
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	few tips first u gotta find a core that can handle that power (500VA) and got enough space for the windings most of the time u can use a core taken from 500VA (or more)transformer also its much easier if u allready got the primmary coil (suited for 120V) if u got all of the above , winding the secondaries wount be a problem

21st January 2005, 06:53 PM	#3
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	I already have the core as mentioned above. Not sure how to calculate the maximum VA rating for it but it but I can stack up the laminations(it does have to be square). I just threw a number for the current but 5Ax50V should only be 250VA, not much for its size. Tom

21st January 2005, 07:19 PM	#4
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	50V @5A ct = 500VA(each secondary 250VA) or maybe u meam 25-0-25 an oversized core is not so good, u will use longer wires=higher output resistance if u got no primary coil u gotta calculate the number of turns for 120V operation , i dont remember the formula for this

22nd January 2005, 02:42 AM	#6
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	here;s an article from a magazine which went bust about a decade ago: http://www.tech-diy.com/rewinding_transformers.htm

22nd January 2005, 07:53 AM	#9
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	Gentlemen, thank you for the assistance. I'll try my best to get something done. Tom

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