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Old 19th September 2012, 06:16 AM   #331
AJT is offline AJT  Philippines
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you are better off with diams in mm as a guide.....as i have kept on repeating, we are not using the same standards wrt copper wire sizes...diameters vary because of insulation thickness there are copper wires that are single, double insulated, still others come with 5x insulations so naturally diameters vary......you don't worry about those things so much.... your goal is to stick those windings in....
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Old 19th September 2012, 07:00 AM   #332
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Quote:
Originally Posted by Tony View Post
you need a bobbin sized for 1 3/4 centre leg stacked to 4 1/2.....
you can get around 1740 volt amperes out of this...
primary turns = 233 turns #16 AWG magnet wire
secondary turns @30volts = 30 turns #13 AWG magnet wire, 4 coils, two bifillar windings....
in my country, the standard is AWG, please take note of this as you may have a different one in yours...
so i go to this transformer,
1.80mm for secondary and for primary 1.25mm.
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Old 19th September 2012, 07:35 AM   #333
AndrewT is offline AndrewT  Scotland
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If you have not bought the 1.8mm wire then consider winding both the primary and the secondary with the 1.25mm diameter wire.
Use dual turns for the secondary. This gives the equivalent of double the copper cross sectional area.
You will find it much easier to wind with 1.25mm wire.
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Old 21st September 2012, 03:57 PM   #334
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Tony, sorry for hijacking the thread [again].

just wondering if anyone has a copy of Reuben Lee's 50's book from t'internet ?

trying to understand the power transformer specification sheet on page 78.
there are various calculations most of which are fine but I cannot see where he is getting the secondary VA of 220 VA, specifically the current part of .081 amps [per volt value ?].
also he seems to be averaging the VA for some strange reason ?

also at bottom left of specification he has 1390 volts ac which miraculously morphs into 1252 volts dc, after which various voltages are deducted for losses etc.
he is putting it through an inductor per the spec but I thought you multiply ac voltage 0.707 when it goes through an inductor, or is it dependent on the value of the inductor ?
if anyone could throw some light much appreciated.

Tony how long does it take you to design one of your transformers on average, do you use a computer program or pencil and paper, do you follow p. turner's site ?
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Old 22nd September 2012, 03:23 AM   #335
AJT is offline AJT  Philippines
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Quote:
Originally Posted by donnyab View Post
Tony, sorry for hijacking the thread [again].

just wondering if anyone has a copy of Reuben Lee's 50's book from t'internet ?

trying to understand the power transformer specification sheet on page 78.
there are various calculations most of which are fine but I cannot see where he is getting the secondary VA of 220 VA, specifically the current part of .081 amps [per volt value ?].
also he seems to be averaging the VA for some strange reason ?

also at bottom left of specification he has 1390 volts ac which miraculously morphs into 1252 volts dc, after which various voltages are deducted for losses etc.
he is putting it through an inductor per the spec but I thought you multiply ac voltage 0.707 when it goes through an inductor, or is it dependent on the value of the inductor ?
if anyone could throw some light much appreciated.

Tony how long does it take you to design one of your transformers on average, do you use a computer program or pencil and paper, do you follow p. turner's site ?
the calculation sheet predicts the dc output voltage across the load...instead of the factor 0.707, he used 0.664 ......

there were 2 secondary coils each rated to provide 110va so the total secondary va adds up to 220va...

i see nothing unusual in the calculation sheet, you just need to digest it by reading it again and again... i might even adopt it.....

because of experience i can design transformers in a matter of minutes having been already familiar with materials available to me........i use pen and paper method
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Old 22nd September 2012, 07:38 AM   #336
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thanks, will go through again later on.
what about your output transformers with the various secondary layers, how to organize them etc. etc. for the different speaker outputs ?
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Old 22nd September 2012, 09:31 AM   #337
AJT is offline AJT  Philippines
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OPT's are a different ballgame.....there are many samples to look at at patrick turner's site as well as that of yves mongmanon...
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Old 10th October 2012, 03:22 AM   #338
mund88 is offline mund88  Philippines
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nice thread sir tony! congrats
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Old 13th December 2012, 08:40 AM   #339
AJT is offline AJT  Philippines
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just finished, my transformer "short circuit" test jig, i was lucky to buy these AC meters at Electromark for 20 pesos each, ranges available are 0-10vac, 0-40vac, then 0-10Aac, and 0-50Aac and selected by toggle switches...

Click the image to open in full size.

Click the image to open in full size.
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Old 14th December 2012, 04:40 AM   #340
AJT is offline AJT  Philippines
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traffo testing:

this is the traffo under test:
center leg of 2 inches stacked to 3 3/4 inch thick, core rating as per RDH4 is about 1750volt-amperes,
the traffo has since been finished with "poly-tuff" automotive filler and painted matte black.....

the purpose of this post is to demonstrate the open circuit(core loss) and short circuit(copper loss) testing of power traffo
to find out efficiencies under load, currents from 1A to 7A were used....

although core rating is 1750VA, i will rate this traffo as a 1200watt power traffo....

Click the image to open in full size.


no load or open circuit testing using a kill-a-watt tester, in this test all secondaries of the traffo are left open...

no load current:

Click the image to open in full size.

no load energy stored:
Click the image to open in full size.

short circuit testing or copper loss test:

in this test all secondary winding's are joined together to form a short, a variac and my test contraption is used,
testing at several point from 1A to 7A....

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

i attach a small spreadsheet showing copper losses at currents from 1 to 7amperes:
Attached Files
File Type: zip traffo testing.zip (9.1 KB, 16 views)

Last edited by AJT; 14th December 2012 at 10:03 PM. Reason: for clarity...
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