This is what I have going on I purchased a 700w mono sub woofer amp which need a 700w transformer 50-0-50 ac out so I decided to build my own transformer for this project I just want to make sure I am doing the math right
transformer core area is 6cm X 3.5cm =21
constant of 42/21 = 2 v.x v.
117v x 2 =234 turns for Primary winding
now for the gauge of the magnet wire this is where I am not sure of?
I divided watts of the amplifier by the source voltage 700x117=5.9amps?
so 15gauge magnet wire on my chart 6.6 amperage I don't think I am doing this part right.
For the secondary winding 50v x 2 =100 turns for each 50v
this is where I think the math is off it says take the watts of the amp dived it by the output voltage 700/50=14amps so I would need a 11 gauge magnet wire. So can someone tell me where I am going wrong?
transformer core area is 6cm X 3.5cm =21
constant of 42/21 = 2 v.x v.
117v x 2 =234 turns for Primary winding
now for the gauge of the magnet wire this is where I am not sure of?
I divided watts of the amplifier by the source voltage 700x117=5.9amps?
so 15gauge magnet wire on my chart 6.6 amperage I don't think I am doing this part right.
For the secondary winding 50v x 2 =100 turns for each 50v
this is where I think the math is off it says take the watts of the amp dived it by the output voltage 700/50=14amps so I would need a 11 gauge magnet wire. So can someone tell me where I am going wrong?
When flux is 1T
VA ~ core area^2 * 31, for sq inches.
VA ~ core area^2 * 0.75, for sq cm.
If you want a different flux then just proportion the result.
eg.
6cm by 3.5cm = 21cm^2
@ 0.8T, the VA is 21^2 * 0.75 * 0.8 = 265VA
or
in sq in
2.36" * 1.38" = 3.255sq in
VA = 3.255^2 * 31 * 0.8 = 263VA
VA ~ core area^2 * 31, for sq inches.
VA ~ core area^2 * 0.75, for sq cm.
If you want a different flux then just proportion the result.
eg.
6cm by 3.5cm = 21cm^2
@ 0.8T, the VA is 21^2 * 0.75 * 0.8 = 265VA
or
in sq in
2.36" * 1.38" = 3.255sq in
VA = 3.255^2 * 31 * 0.8 = 263VA
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This is all new to me I think I have math right for how many turns for the primary & secondary but when it comes to the magnet wire size that were I get confused
This is the site I got the info from Como calcular un transformador de corrienteAny help to get me on the right track would be appreciated.
Life is a enigma, In post 2 Andrew was trying to tell you that your transformer is to small for 700W. (His equation was not written properly)
"6cm by 3.5cm = 21cm^2
@ 0.8T, the VA is 21^2 * 0.75 * 0.8 = 265VA"
He is saying your transformer is good for about 265 Watts at .8 Tesla. You need a transformer about twice as big.
(42 cm^2)^2 x .75 x .8 Tesla = 1058 W
(35 cm^2)^2 x .75 x .8 Tesla = 735W
(30 cm^2)^2 x .75 x .8 Tesla = 540W
(21 cm^2)^2 x .75 x .8 Tesla = 264W
So you have to find a transformer with a core area of at least 35CM^2
See if you can find this transformer and then i will help with wire size.
"6cm by 3.5cm = 21cm^2
@ 0.8T, the VA is 21^2 * 0.75 * 0.8 = 265VA"
He is saying your transformer is good for about 265 Watts at .8 Tesla. You need a transformer about twice as big.
(42 cm^2)^2 x .75 x .8 Tesla = 1058 W
(35 cm^2)^2 x .75 x .8 Tesla = 735W
(30 cm^2)^2 x .75 x .8 Tesla = 540W
(21 cm^2)^2 x .75 x .8 Tesla = 264W
So you have to find a transformer with a core area of at least 35CM^2
See if you can find this transformer and then i will help with wire size.
Life is a enigma, I just thought of something. This is for audio. You can get buy with some real junk for audio. Because of the mostly average and sometimes peak power needed you can probably get by with 1/3 the power rating of the transformer. So the one you have will be just big enough, if the windings fit.
Do you have a bobbin for this transformer. If so what is the winding width and height.
Do you have a bobbin for this transformer. If so what is the winding width and height.
well that not good I appreciate the help from you guys. This do it my self project is being a pain in my butt. So does anyone know where I can get a E-I core kit that will fit my needs for this project?
Yes that's where I measured it from. The core I have it a old microwave transformer.
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I just got lucky and found this old transformer on Ebay for $57.30 shipped
Big old electro-magnetic transformer- nominal output
stated in the title; removed from vintage amplifiers.
I measured 52-53 volts between adjacent secondary taps
(no load, 105V total) at 123 VAC input..
Measures 5-1/4 x 5.0 x 4-3/8" and weighs 17 lbs.
What do you thinks guys do you think this transformer will do the job?
Below Links will be help you to calculate a transformer.
Como calcular un transformador de corriente
construya un transformador casero
Como calcular un transformador de corriente
construya un transformador casero
But you need the AC VA rating to be perhaps 2-3 times the DC W rating if you use a capacitor input PSU. Hence for a 700W output power amp, which will draw perhaps 900W DC power at peak (if Class B) you need a 2kW transformer for continuous use. If it is handling real music with peaks and troughs then a 700W transformer may be fine. Less than this will not be fine.powerbob said:
no doubt that traffo will work.....
What makes you say that? The amplifier board I have recommends a Power: AC dual 45 ~ 50V (300W ~ 700W), and a single exchange of about 15V (10W) and the Peak power output 700W mono at 4 ohms. So 700w = about 7 amp draw ac so a 8 amp transformer should do more then the job I am asking of it. So if I am wrong please let me know. It is better to ask a question then trying to guess the answer I don't quite understand.
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