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-   -   Building a power supply unit. (http://www.diyaudio.com/forums/chip-amps/18608-building-power-supply-unit.html)

 S.C 5th August 2003 01:19 AM

Building a power supply unit.

If i want to make a psu with two transformer, can I use only one female power pot? Parallel connect it to them. Am I using one fuse also?

 jh6you 5th August 2003 08:17 AM

Yes and yes. I have made so without any tech problem.

:yinyanng:

 S.C 6th August 2003 02:53 AM

Last few questions,

1. You guys said 160VA-250VA(watt) per channel will be enough "save". Does it apply to the transformer before bridge or after?

As an example,

1. a 250VA Transformer 115V Primary, 25V/25V Secondary, and 10A. Bridge: *1.414. Finally = (25*1.414)V*10A = 353.5

Or

2. a 250VA PSU, Transformer: Pri: 115V, Sec: 17.7V/17.7V, and 10A, Bridge: *1.414. Finally = (17.7*1.414)V*10A = 249.4VA?

Which one is right?

2. Does Secondary Voltage important to match the datasheet's graph? Or I just need to get enough VA(watt) rating?

Ex:

Speaker: 10 Ohm, 35W. Target Power supply 20V Power rail 26-
28V each.

Transformer A: Pri 115V, Sec 20V/20V, 12.5A
Bridge: *1.414 = (20*1.414)V12.5A = 353.5VA Per Channel

Or

Transformer B: Pri 115V, Sec 12V/12V, 20.8A
Bridge: *1.414 = (12*1.414)V20.8A = 352.9VA Per Channel

3: If I am going to have some high current transformer such as above. Can a 3.15A fuse handle it, like Nuuk's site suggested? How is fuse work?

My guess:
If it break when there is more than 3.15A go through it, then I should use higher rating fuse for those high current transformer, right?

All those through are my guessing only. Plz correct me, and my math. Feel Free to comment.:scratch:

 Mad_K 6th August 2003 05:52 AM

#before bridge

250VA 2*18V => 250/(18+18)=6,94A

VA=2*18*6,94=250VA

 S.C 6th August 2003 08:59 PM