possible source of transformers??

zx3chris · 12th February 2003, 02:46 AM

anyone ever think of taking the transformer out of a computer power supply?? you can buy 250 watt continous atx power supplies for around $30US... just an idea..

for example, http://www.newegg.com/app/viewProduc...154-009&depa=0

not all ps's are rated in continous power, but even 150watts continous for $19 isnt bad.

if u needed more than 12-0-12 use two or more...

-chris

Sch3mat1c · 12th February 2003, 02:59 AM

Um..perfect...if you live in a world of 100kHz power transmission......

Tim

zx3chris · 12th February 2003, 03:02 AM

i have no idea what you mean, im a n00b... explanation????

JBL · 12th February 2003, 03:06 AM

Computer psu are switch mpode power supply.

Simply they converte the 60 hz ac to dc and then switch it at a high frequency(around 100khz) to enable it to be converted by a smaller transformer.

Their is many advantage to this but it's complicate ths psu alot.

Sch3mat1c · 12th February 2003, 03:09 AM

Due to nothing being ideal, no transformer works the same at any frequency. They have to be made for a certain range.

For 50/60Hz which comes out of your wall, the transformers need to be large and heavy, with lots of turns.
For 100kHz (as in a typical switching supply), you only need a few turns to get a lot of voltage done. The core material also can be much smaller, making for a very small transformer overall.

If you tried connecting a 100kHz transformer up to even 10kHz, and try sending the same power through it, it will smoke instantly, I absolutely guarantee it.

Tim

zx3chris · 12th February 2003, 03:27 AM

thank you for the replies, i appreciate the information as compared to arrogant and cocky comments by the majority of the members on this site... ok i understand what you are saying.. i know that Erms = 4.44*N*f*PhiMax, and that if you increase f, all others variables are constants except for phimax, so that must increase.. the graph of B vs H is a saturation curve, so when u reach saturation and B increases a little, H (mag field intensity) must increase alot -- causing more current to be drawn, and poof... no more trannie... but, what if you just look at the comp ps as black box --- Ac in .. +/-12V out... that can be used no??

-chris

ThingyNess · 12th February 2003, 03:51 AM

Unfortunately no, becuase 99% of the computer power supplies just use a simple linear regulator on the -12V line such as an LM337, or 7912, and they usually give 0.8 -> 1.2 amps max.

This won't give you much of an amplifier.

Switchmode power supplies do exist that put out lots of power, and with symmetrical currents on the positive and negative rails, but they aren't used in computers, and aren't cheap.

zx3chris · 12th February 2003, 03:55 AM

ah ok.. thanks again.. i just checked an old at supply i had laying around.. it said 12v 12A but only .5A at -12v... thanks again

Sch3mat1c · 12th February 2003, 04:14 AM

AT supplies usually have a lot of nice parts in them. HV 'lytics, film caps, HV transistor(s) for the input side, and low ESR caps on the output.

Oh, for the days when they knew how to do things with discrete parts, not an all-in-one single-use IC...sigh

Tim

12th February 2003, 02:46 AM	#1
zx3chris diyAudio Member Join Date: Oct 2002 Location: south amboy nj	possible source of transformers?? anyone ever think of taking the transformer out of a computer power supply?? you can buy 250 watt continous atx power supplies for around $30US... just an idea.. for example, http://www.newegg.com/app/viewProduc...154-009&depa=0 not all ps's are rated in continous power, but even 150watts continous for $19 isnt bad. if u needed more than 12-0-12 use two or more... -chris

12th February 2003, 03:06 AM	#4
JBL diyAudio Member Join Date: Aug 2001 Location: Canada, N.-B.	Computer psu are switch mpode power supply. Simply they converte the 60 hz ac to dc and then switch it at a high frequency(around 100khz) to enable it to be converted by a smaller transformer. Their is many advantage to this but it's complicate ths psu alot. __________________ Jonathan Blanchard (J.Bl.) ---Nothing is impossible---

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12th February 2003, 02:59 AM	#2
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	Um..perfect...if you live in a world of 100kHz power transmission...... Tim

12th February 2003, 03:02 AM	#3
zx3chris diyAudio Member Join Date: Oct 2002 Location: south amboy nj	i have no idea what you mean, im a n00b... explanation????

12th February 2003, 03:09 AM	#5
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	Due to nothing being ideal, no transformer works the same at any frequency. They have to be made for a certain range. For 50/60Hz which comes out of your wall, the transformers need to be large and heavy, with lots of turns. For 100kHz (as in a typical switching supply), you only need a few turns to get a lot of voltage done. The core material also can be much smaller, making for a very small transformer overall. If you tried connecting a 100kHz transformer up to even 10kHz, and try sending the same power through it, it will smoke instantly, I absolutely guarantee it. Tim

12th February 2003, 03:27 AM	#6
zx3chris diyAudio Member Join Date: Oct 2002 Location: south amboy nj	thank you for the replies, i appreciate the information as compared to arrogant and cocky comments by the majority of the members on this site... ok i understand what you are saying.. i know that Erms = 4.44Nf*PhiMax, and that if you increase f, all others variables are constants except for phimax, so that must increase.. the graph of B vs H is a saturation curve, so when u reach saturation and B increases a little, H (mag field intensity) must increase alot -- causing more current to be drawn, and poof... no more trannie... but, what if you just look at the comp ps as black box --- Ac in .. +/-12V out... that can be used no?? -chris

12th February 2003, 03:51 AM	#7
ThingyNess diyAudio Member Join Date: Feb 2002 Location: Vancouver, BC, Canada	Unfortunately no, becuase 99% of the computer power supplies just use a simple linear regulator on the -12V line such as an LM337, or 7912, and they usually give 0.8 -> 1.2 amps max. This won't give you much of an amplifier. Switchmode power supplies do exist that put out lots of power, and with symmetrical currents on the positive and negative rails, but they aren't used in computers, and aren't cheap.

12th February 2003, 03:55 AM	#8
zx3chris diyAudio Member Join Date: Oct 2002 Location: south amboy nj	ah ok.. thanks again.. i just checked an old at supply i had laying around.. it said 12v 12A but only .5A at -12v... thanks again

12th February 2003, 04:14 AM	#9
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	AT supplies usually have a lot of nice parts in them. HV 'lytics, film caps, HV transistor(s) for the input side, and low ESR caps on the output. Oh, for the days when they knew how to do things with discrete parts, not an all-in-one single-use IC...sigh Tim

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