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mil thick to AWG

Posted by: wekers on Fri, 10/07/2016

Dear all,


Transformer build

Output: 12V 5A
My secondary wind is: (from PI Expert Suite)

Copper Foil: 5 mil thick, 11.20 mm wide, covered with 1 layer of lapped tape. Terminations to foil: 2 x 23 AWG magnet wire with sleeving



How convert mil trick to AWG? i am very confuse about that


Edited: i see now in pi expert, options on secondary wind construction, modified "Winding Type" to Single and now show 18AWG, but still confuse about type "foil mil". I mean what is "foil mil", here in my Country market we only use AWG or mm2


Submitted by wekers on Fri, 10/14/2016

my mistake to interpret, just one thing yet, 11.20mm wide, its correct?

to take out the doubt, someone can post a picture of this type of wire used on secondary(i.e: Copper Foil: 5 mil thick, 11.20 mm wide),

because i only know, magnetic wire, TIW wire and litz wire.

Submitted by wekers on Sun, 10/16/2016

Sorry my ignorance, i'm just started recently to study about smps,

i get it what is.


Attachment Size
copper_foil.jpeg 20.75 KB
Submitted by PI-Traveler on Mon, 10/17/2016

Hi Wekers,

This is correct. Copper foil is usually used for designs for medium to high output power. This is done to increase current density of the transformer.


May I ask what id the end application of your design? I can help you check your transformer spreadsheet if you want to.

Submitted by wekers on Mon, 10/17/2016

In reply to by PI-Traveler

Now is just for learn about, I did a prototype 85-265 VAC Input -> 12V 5A Output Core/Bobbin (E30/15/14) on breadboard, work as well, i used for secondary TIW, didn't know before i could use Copper Foil for this work.

I did on breadboard, not like mount circuit with frequency in that, but all things i always mount on breadboard first, if work ok, ready to make a pcb

Attachment Size 2.18 MB
Submitted by wekers on Mon, 10/17/2016

In reply to by PI-Traveler

More one question, i can use this one?…

or 0,15mm thickness, here is hard to found, i ask because i have plan to make a 14,5V 10A CV/CC charger application next,

the TOP271EG its ok for that?

PS: is only for prototype, course if i decided to make the product of part of this SMPS, i will order to build on specialists of PCB Assembly

Submitted by wekers on Wed, 10/19/2016

In reply to by PI-Traveler

I check that for design 14,5V x 12A reaches the limit of TOP271.. I research that for more power you have HiperTFS-2, but require 380VDC so i will need HiperPFS-2 or HiperPFS-3 correct?

The HiperPFS looks simple to make a circuit, but HiperTFS-2 seems more difficult.

I'll get TFS7705H and PFS7329H these parts It was what I found easy in market, is ok for my design? I mean if have problem to use one ic that is more powerfull than i need (i think not problem).
BTW if i get these ic's, i can ask here in forum, for example: how build transformer for HiperTFS-2 correctly and other doubts

Submitted by PI-Traveler on Fri, 10/21/2016

In reply to by wekers

This should be ok for prototype purposes. You might need to check if the added thickness will not cause your transformer to be too "bulky". The thicker copper strip will actually result in a much cooler transformer.