Toroid Wiring for Chip Amp

hongrn · 26th October 2005, 06:15 PM

I need to rewire my LM4780 amp to eliminate a ground loop issue. I have an Avel Lindberg 330VA 25Vx25V that I need to configure to have a center tap, in other words, 25V-0-25V. Please take a look at this schematic and tell me how to wire this.

If I wired both primaries and secondaries in series, I'll end up with 230V for the primaries, and 50VAC for the secondaries. I only need 25VAC (rectified into 35VDC) for my amp. Do I use this wiring scheme and plug it in to get 25VAC, since we have 120VAC in the US? Or do I keep the primaries in parallel and wire the secondaries in series?

Thank you for your help.

motherone · 26th October 2005, 06:26 PM

You have dual primaries so that you can put the primaries in series or parallel for 115/230VAC. The secondaries are the same way (25VAC @ double the current, or 25-0-25).

So, the answer to your question is to put the primaries in parallel and the secondaries in series. You should definitely read up on how transformers work, though, so you understand why you're doing this.

hongrn · 26th October 2005, 06:28 PM

I've been at the Decibel Dungeon many times, just want to make sure I wire it correctly before plugging in my amp.

Thank you motherone.

BWRX · 26th October 2005, 06:33 PM

Also read through these web pages if you haven't already:

http://www.zero-distortion.com/techn...ly/powersi.htm

Good info. and it will show you the different ways you can build a +/- linear supply.

troystg · 26th October 2005, 06:38 PM

Use the top left picture for the primaries and the bottom right for the secondaries. The tie piont fo the series coils needs to go to the Pwr supply ground (not the same as chassis ground) and you will have to use a bridge rectifier or a descrete bridge.. You will not be able to use the descret diodes in BrianGT's pwr supply board with out jumpers or modification...

motherone · 26th October 2005, 06:41 PM

Do you mean top right for primaries, and bottom right for secondaries?
The top left picture is just to show the color codes in relation to how the transformer is wound.

troystg · 26th October 2005, 07:10 PM

Quote:

Originally posted by motherone
Do you mean top right for primaries, and bottom right for secondaries?
The top left picture is just to show the color codes in relation to how the transformer is wound.

YES... My bad... Top right actually shows them paralleled.

hongrn · 26th October 2005, 07:13 PM

I am wiring the primaries in parallel and the secondaries in series. Thanks everyone.

Hong

budwiser · 26th October 2005, 08:36 PM

Picture paints a thousand words. I use the same tranny from avel. Picture shows how I wired it for brians chipamp.

http://www.briangt.com/gallery/nigc-budwiser/PICT0066

troystg · 26th October 2005, 08:49 PM

Quote:

Originally posted by budwiser
Picture paints a thousand words. I use the same tranny from avel. Picture shows how I wired it for brians chipamp.

http://www.briangt.com/gallery/nigc-budwiser/PICT0066

Note that yours is a dual secondary and the secondaries are in parallel to seperate bridges.

NOT the same as a series connection with center tap to a common grnd.

26th October 2005, 06:15 PM	#1
hongrn diyAudio Member Join Date: Mar 2005 Location: Placentia, CA, USA	Toroid Wiring for Chip Amp I need to rewire my LM4780 amp to eliminate a ground loop issue. I have an Avel Lindberg 330VA 25Vx25V that I need to configure to have a center tap, in other words, 25V-0-25V. Please take a look at this schematic and tell me how to wire this. If I wired both primaries and secondaries in series, I'll end up with 230V for the primaries, and 50VAC for the secondaries. I only need 25VAC (rectified into 35VDC) for my amp. Do I use this wiring scheme and plug it in to get 25VAC, since we have 120VAC in the US? Or do I keep the primaries in parallel and wire the secondaries in series? Thank you for your help.

26th October 2005, 06:38 PM	#5
troystg diyAudio Member Join Date: Apr 2004 Location: Lousy Anna	Use the top left picture for the primaries and the bottom right for the secondaries. The tie piont fo the series coils needs to go to the Pwr supply ground (not the same as chassis ground) and you will have to use a bridge rectifier or a descrete bridge.. You will not be able to use the descret diodes in BrianGT's pwr supply board with out jumpers or modification... __________________ Troy Thinking positive doesn't make things better, it makes you a better person.

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26th October 2005, 06:26 PM	#2
motherone diyAudio Member Join Date: Apr 2003 Location: Seattle	You have dual primaries so that you can put the primaries in series or parallel for 115/230VAC. The secondaries are the same way (25VAC @ double the current, or 25-0-25). So, the answer to your question is to put the primaries in parallel and the secondaries in series. You should definitely read up on how transformers work, though, so you understand why you're doing this.

26th October 2005, 06:28 PM	#3
hongrn diyAudio Member Join Date: Mar 2005 Location: Placentia, CA, USA	I've been at the Decibel Dungeon many times, just want to make sure I wire it correctly before plugging in my amp. Thank you motherone.

26th October 2005, 06:33 PM	#4
BWRX diyAudio Moderator Emeritus Join Date: Jan 2005 Location: Pennsylvania	Also read through these web pages if you haven't already: http://www.zero-distortion.com/techn...ly/powersi.htm Good info. and it will show you the different ways you can build a +/- linear supply.

26th October 2005, 06:41 PM	#6
motherone diyAudio Member Join Date: Apr 2003 Location: Seattle	Do you mean top right for primaries, and bottom right for secondaries? The top left picture is just to show the color codes in relation to how the transformer is wound.

26th October 2005, 07:13 PM	#8
hongrn diyAudio Member Join Date: Mar 2005 Location: Placentia, CA, USA	I am wiring the primaries in parallel and the secondaries in series. Thanks everyone. Hong

26th October 2005, 08:36 PM	#9
budwiser diyAudio Member Join Date: Jan 2004 Location: Greenwood, IN	Picture paints a thousand words. I use the same tranny from avel. Picture shows how I wired it for brians chipamp. http://www.briangt.com/gallery/nigc-budwiser/PICT0066

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