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Old 3rd August 2005, 07:36 PM   #1
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Default Volt Amp Estimation

I have salvaged a torroid transformer from an old computer soundsystem that is marked TOU433017F2. It is +/- 19v secondaries. Is there anyway to estimate a VA rating for it, since I can't seem to find any information on this particular transformer.
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Old 3rd August 2005, 08:10 PM   #2
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Default If all you need is a guesstimate......

The dimensions would be a good starting place. Compare it to known transformers.

Jocko
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Old 4th August 2005, 01:39 AM   #3
Stocker is offline Stocker  United States
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The more important dimension is the hardest to measure. the cross-sectional area of the core's center piece.
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Old 4th August 2005, 02:08 AM   #4
Leolabs is offline Leolabs  Malaysia
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Not forget the weight too
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Old 4th August 2005, 03:51 AM   #5
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Default Find some wire resistance, alike the one we use in electric showers...

And prepare one segment that can measure 3 or 4 ohms.

And them short circuit one of the extreme taps with the center tap using those small value wire resistor between them.

The result you have in this transformer half, will say to you that you will have almost the same result to the other half...if you want guarantee against core saturations, load both sides with two resistors.... make rectification and filtering, having positive and negative voltages referenced to the center tap.

You will producing a 3 or 4 ohms loads (you decide the value) to that transformer.

Now attach a Voltimeter, reading AC voltage into those resistor extremes, and this will be the center transformer tap and one of the extreme tap.... so, over the resistor, connected to the resistor extremes.

Now plug into the wall outlet...you will have a hot resistance and will measure some voltage..... lets say 12 volts over the 4 ohms resistor.....this result in 3 amperes...or something around it, as resistor overheated change its resistance...no more 4 ohms.

To calculate the power, in this case, 3 amperes and 12 volts represents 36 watts for this transformer half...... converting to DC will be easy to have a simetrical supply of more than 15 volts plus and minus with more than 72 watts of total capacity.

I have some doubts using that method to AC...normally i use to rectified and filter after my measurements.... to have a real voltage and to check my filtering capacity related the current...to know if my electrolitic filter condenser is working good, beeing enought or not, for the current produced by some transformer.

After rectification and filtering, i guarantee that results are very precise...those made with AC, I personally have my doubts.

So, to have a more realistic result, make your rectification and install good filters, and them you will have a real value related your tranformer qualities, putting it to work, loaded, and measuring the real voltages.

regards,

Carlos
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Old 4th August 2005, 04:23 AM   #6
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Default Here is some sketch with the idea

Good luck.

regards,

Carlos
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Old 4th August 2005, 04:25 AM   #7
jaycee is offline jaycee  United Kingdom
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What was the primary winding fuse rated at?
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Old 4th August 2005, 04:31 AM   #8
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Default Good Jaycee, simple, direct, precise..congratulations

Multiplying the fuse by the mains voltage, you will have the power in primary...this power will be reflected in the secondary.

Great Jaycee!.... the best way to do the things continue to be the more simple methods...very good.

regards,

Carlos
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Old 5th August 2005, 02:40 AM   #9
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~ 50VA per pound.
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