how to wind toroid transformer?

openport · 14th February 2011, 09:52 PM

Hi,
i'm trying to make my first SMPS inverter and i need some help.
the inverter makes +-24Volt supply out of 12 volts.
i calculated that if i use a D_out=30mm, D_in=20mm, h=10mm toroid, i'dd have to make 2X4 turns primary and 2X11 turns secondary. i use SG2525A for the controller @ around 70kHz.
i use total of 4 IRF1010N and 4 FES16DT for the diodes.
it should power 4 channels with 70-75 W rms @ 4 ohms or 2 channels with ~250 W rms @ 4 ohms. will 8 amp rating be enough for the trafo4?

now i haven't wound any toroids before and i need help.
i think it might look something like this:

how wrong am i? any tips?
is 0.5mm wire ok for the task?(in bundles)
thats for 8 amps and it makes 8 wires for the primary windings and 5 wires for the secondary...

does any of it make sense?
Thanks!

ChrisA · 14th February 2011, 10:32 PM

Quote:

Originally Posted by openport

Hi,
i'm trying to make my first SMPS inverter and i need some help.
the inverter makes +-24Volt supply out of 12 volts.
i calculated that if i use a D_out=30mm, D_in=20mm, h=10mm toroid, i'dd have to make 2X4 turns primary and 2X11 turns secondary. i use SG2525A for the controller @ around 70kHz.

You are going to have to show us a schematic. First off I can't see how you can use two primaries.

Next you are talking about 240W of power I just don't see that happinging with a small transformers like this.

What is the core material?

openport · 10:46 PM

here are the schematics. car amp inverter trafo

its a class D car amp.
i haven't figured out the core material yet.

mastodon · 15th February 2011, 11:30 AM

Schematics don't show up in the thread you linked to...

openport · 15th February 2011, 01:04 PM

sorry.
here are the schematics.
http://imageupload.org/?di=812977785457
http://imageupload.org/?di=1012977785473
http://imageupload.org/?di=1012977785472

Thanks.

areza · 15th February 2011, 04:28 PM

both primary should be BIFILAR and cover whole CIRCUMFERENCE of the core

openport · 15th February 2011, 09:55 PM

does anybody know a tutorial or something?
i have searched the internet for a week now. and i can't find a decent tutorial on small core trafos. they all show how to make one if you use the grid. i use a battery.

how should the trafo look like if i use Bifilar winding
so one primary should cover half of the core

richie00boy · 15th February 2011, 10:03 PM

Bifilar means take two wires together and wind together. You should always evenly cover the way round the toroid, especially when there is just a few turns.

openport · 16th February 2011, 05:12 AM

i mean how do i have to wind it if i have to use 8 wires?
just like 4 bifilar coils side by side?

areza · 16th February 2011, 05:26 PM

u can do some experiment on various bifilar winding techniques and let us know the results, some twist both the primary and wind, others lay the wires side by side(pri 1 - pri 2 - pri 1.......), some even go a bit farther and twist the primary and secondary together, all these techniques has deferent pros and cons, if i am building a 12v to 24v dc/dc and dont need tight voltage regulation then, i would try to twist all the primary and secondary together and wind and see what happen.

14th February 2011, 09:52 PM	#1
openport diyAudio Member Join Date: Nov 2010	how to wind toroid transformer? Hi, i'm trying to make my first SMPS inverter and i need some help. the inverter makes +-24Volt supply out of 12 volts. i calculated that if i use a D_out=30mm, D_in=20mm, h=10mm toroid, i'dd have to make 2X4 turns primary and 2X11 turns secondary. i use SG2525A for the controller @ around 70kHz. i use total of 4 IRF1010N and 4 FES16DT for the diodes. it should power 4 channels with 70-75 W rms @ 4 ohms or 2 channels with ~250 W rms @ 4 ohms. will 8 amp rating be enough for the trafo4? now i haven't wound any toroids before and i need help. i think it might look something like this: how wrong am i? any tips? is 0.5mm wire ok for the task?(in bundles) thats for 8 amps and it makes 8 wires for the primary windings and 5 wires for the secondary... does any of it make sense? Thanks!

14th February 2011, 10:41 PM	#3
openport diyAudio Member Join Date: Nov 2010	here are the schematics. car amp inverter trafo its a class D car amp. i haven't figured out the core material yet. Last edited by openport; 14th February 2011 at 10:46 PM.

15th February 2011, 10:03 PM	#8
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Bifilar means take two wires together and wind together. You should always evenly cover the way round the toroid, especially when there is just a few turns. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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15th February 2011, 11:30 AM	#4
mastodon diyAudio Member Join Date: Jan 2011	Schematics don't show up in the thread you linked to...

15th February 2011, 01:04 PM	#5
openport diyAudio Member Join Date: Nov 2010	sorry. here are the schematics. http://imageupload.org/?di=812977785457 http://imageupload.org/?di=1012977785473 http://imageupload.org/?di=1012977785472 Thanks.

15th February 2011, 04:28 PM	#6
areza diyAudio Member Join Date: Jun 2007	both primary should be BIFILAR and cover whole CIRCUMFERENCE of the core

15th February 2011, 09:55 PM	#7
openport diyAudio Member Join Date: Nov 2010	does anybody know a tutorial or something? i have searched the internet for a week now. and i can't find a decent tutorial on small core trafos. they all show how to make one if you use the grid. i use a battery. how should the trafo look like if i use Bifilar winding so one primary should cover half of the core

16th February 2011, 05:12 AM	#9
openport diyAudio Member Join Date: Nov 2010	i mean how do i have to wind it if i have to use 8 wires? just like 4 bifilar coils side by side?

16th February 2011, 05:26 PM	#10
areza diyAudio Member Join Date: Jun 2007	u can do some experiment on various bifilar winding techniques and let us know the results, some twist both the primary and wind, others lay the wires side by side(pri 1 - pri 2 - pri 1.......), some even go a bit farther and twist the primary and secondary together, all these techniques has deferent pros and cons, if i am building a 12v to 24v dc/dc and dont need tight voltage regulation then, i would try to twist all the primary and secondary together and wind and see what happen.

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