Antiphase wired second transformer in a 65-0-65 PSU to reduce ripple

the toasted · 16th February 2003, 02:39 PM

Hi everybody!

What I want to do ist to reduce the current ripple in my 65V-0V-65V (5A-0-5A) PSU.
It is based on:
2x block transformer (230V/46V 320VA)
8x 4700myF/100V electrolytic filter capacitors
2x 700V/35A metall bridge rectifier
4x 10myF MKP capacitors (2 per rail)
and 2 4k7/10W resistors

I use it to power my 2x150W A/B solid state power amplifier.

My question is:
Can I reduce the ripple current by wireing the second transformer antiphase so that the maximum + of the one trafo is at the same time than the max - of the other trafo?

I thought, that this would smooth the ripple at the end of the PSU and give a cleaner voltage for the amp.

Is this right? Please give me your suggestions!

Thanks,
the toasted

megajocke · 16th February 2003, 02:53 PM

How are they connected? Do you use one for plus and one for minus, or are they connected in series? If you use one transformer for minus and the other for plus it won't make a differece as the circuit is symmetrical.

If you use it with center tap (but you said 2 rectifiers so I guess not) then they should be connected so that the ends of the windings are in anti-phase.

k.junold · 17th February 2003, 01:20 PM

I use them with center tap -> so you wrote what I wanted to know! Sorry for my bad explanation.
I use two rectifiers (like in a circuit of Anthony Holton http://www.aussieamplifiers.com ).
Thanks for your help!

megajocke · 17th February 2003, 07:48 PM

is it this one? It looks like the author got some kind of brain fart there??? If you trace from the bottom end of the transformer, going through two forward biased diodes you end up at the other end! Could you please explain (or draw) your configuration...

Or have you connected the center tap to 0V and use one bridge per channel?

SY · 17th February 2003, 08:28 PM

4700 uF is mighty skimpy for a 150 W amp. The best thing you could do is to take that up to 20,000 uF or so. That will take your ripple below audibility.

megajocke · 18th February 2003, 12:56 PM

Quote:

Originally posted by SY
4700 uF is mighty skimpy for a 150 W amp. The best thing you could do is to take that up to 20,000 uF or so. That will take your ripple below audibility.

He says he has eight of them. That's 18800µF per rail.

SY · 18th February 2003, 02:13 PM

I misinterpreted; I thought that he had two rails, two channels. If he's got 10-20KuF, his question should be, why do I have any significant ripple in the first place? Grounding problems?

16th February 2003, 02:39 PM	#1
the toasted diyAudio Member Join Date: Feb 2003 Location: Bayreuth	Antiphase wired second transformer in a 65-0-65 PSU to reduce ripple Hi everybody! What I want to do ist to reduce the current ripple in my 65V-0V-65V (5A-0-5A) PSU. It is based on: 2x block transformer (230V/46V 320VA) 8x 4700myF/100V electrolytic filter capacitors 2x 700V/35A metall bridge rectifier 4x 10myF MKP capacitors (2 per rail) and 2 4k7/10W resistors I use it to power my 2x150W A/B solid state power amplifier. My question is: Can I reduce the ripple current by wireing the second transformer antiphase so that the maximum + of the one trafo is at the same time than the max - of the other trafo? I thought, that this would smooth the ripple at the end of the PSU and give a cleaner voltage for the amp. Is this right? Please give me your suggestions! Thanks, the toasted

17th February 2003, 01:20 PM	#3
k.junold diyAudio Member Join Date: Apr 2001	Thanks! I use them with center tap -> so you wrote what I wanted to know! Sorry for my bad explanation. I use two rectifiers (like in a circuit of Anthony Holton http://www.aussieamplifiers.com ). Thanks for your help!

17th February 2003, 08:28 PM	#5
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	4700 uF is mighty skimpy for a 150 W amp. The best thing you could do is to take that up to 20,000 uF or so. That will take your ripple below audibility. __________________ If there's a sucker born every minute, where do the rest of them come from?

18th February 2003, 02:13 PM	#7
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	I misinterpreted; I thought that he had two rails, two channels. If he's got 10-20KuF, his question should be, why do I have any significant ripple in the first place? Grounding problems? __________________ If there's a sucker born every minute, where do the rest of them come from?

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16th February 2003, 02:53 PM	#2
megajocke diyAudio Member Join Date: Jan 2003	How are they connected? Do you use one for plus and one for minus, or are they connected in series? If you use one transformer for minus and the other for plus it won't make a differece as the circuit is symmetrical. If you use it with center tap (but you said 2 rectifiers so I guess not) then they should be connected so that the ends of the windings are in anti-phase.

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