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
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
Somebody wants you to do this... I found this earlier today...
Roll your own power transformers
Do let us know how it turns out!
Roll your own power transformers
Do let us know how it turns out!
here;s an article from a magazine which went bust about a decade ago:
http://www.tech-diy.com/rewinding_transformers.htm
http://www.tech-diy.com/rewinding_transformers.htm
*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
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
sss said: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.
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
50v @5amps is 250Va, but primary VA needs to be around 350va.....looks like a 1.5 inch center leg stacked to 2.5 inches height is good.
primary turns of about 280 of ga #19 using grain oriented silicon steel, more if not using goss...
secondary turns of 120 #14 split into 2 coils of 60 turns each...wired in series to get the center tap.
you have to find out your coil buildup and adjust turns or wire size to fit into the window of your EI cores.
if you can get hold of a bobbin, then scramble winding is easier to do... you only need to worry about primary and secondary coil insulations.....
Hello tmblack
If your have line voltage 120 at 50 hz and want 50 ct with 5A
Than do this Ei stack center lag E=37.5 mm , Stack height 54 mm ,assume 54 vac for winding
Primary winding turn = 266 with SWG 18 (1.22 Diameter mm)
secondary Winding Turn = 120 with Swg 16 (1.63 Di mm)
you need 3.5 kg EI lamination and 0.920 kg Copper total
All of this you get loaded 50vac with 5A = around 250VA
please replay soon
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do not ask for confirmation, just do it....as you build lots and lots of them, you will have the confidence and experience and we can not give that to you on a silver platter......you have to do it yourself...
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