Definitive Build

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pre65
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#31 Re: Definitive Build

Post by pre65 »

simon wrote: Sun Jan 30, 2022 10:16 pm Sounds like a bipolar PS - +0-. If so the two caps joining - to + will be ground or 0V most likely, the point in the middle. Think of the two caps stacked vertically - from top to bottom the top cap will be + above -, the bottom cap will be + at the top - at the bottom. The negative of the top cap is joined to the + of the bottom cap.
I understand that Simon, but that way you get half the capacitance of one capacitor on it's own but you double the voltage rating (with resistors across pos/neg on each capacitor).

Dennis is trying to increase capacitance, so as long as the capacitor voltage rating is above the rail voltage (by a fair margin) surely capacitors in parallel is what's needed ? (ie all pos connected together and all neg connected together)

10,000uf + 10,000uf (@50v) in series = 5,000uf @ 100v

10,000uf + 10,000uf (@ 50v) in parallel = 20,000uf @ 50v






;
Last edited by pre65 on Sun Jan 30, 2022 10:33 pm, edited 1 time in total.
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#32 Re: Definitive Build

Post by simon »

I'm only guessing (dangerous) from what Dennis said. This sounds like his PS? There may or may not be a ground connection going in to the caps.
20220130_222517.jpg
20220130_222517.jpg (99.29 KiB) Viewed 745 times
So paralleling caps would look like this
20220130_222416.jpg
20220130_222416.jpg (108 KiB) Viewed 745 times
But I'm only guessing.
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#33 Re: Definitive Build

Post by pre65 »

OK, those diagrams make sense. :)


Dennis, see how a diagram make everything easy to understand.
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#34 Re: Definitive Build

Post by simon »

I'm only guessing though, based on this
Daniel Quinn wrote: Sun Jan 30, 2022 9:18 pm Nope the power supply ain’t separate and using two capacitors the plus is joined to negative with a bar on one terminal . And the other connector gives the + and ~ for the power amp board
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#35 Re: Definitive Build

Post by Ray P »

simon wrote: Sun Jan 30, 2022 11:06 pm I'm only guessing though, based on this
Daniel Quinn wrote: Sun Jan 30, 2022 9:18 pm Nope the power supply ain’t separate and using two capacitors the plus is joined to negative with a bar on one terminal . And the other connector gives the + and ~ for the power amp board
That's how I pictured it too Simon. You might get some benefit from turning it into a CRC arrangement depending on the context?
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#36 Re: Definitive Build

Post by andrew Ivimey »

Erm...... surely where the caps are joined positive and negative they also need to be grounded as does the centre tap of the secondary winding of the transformer. Otherwise you won't get pos, 0, - negative power supply you'll get positive, half positive and zero volts on the bottom.
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#37 Re: Definitive Build

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andrew Ivimey wrote: Mon Jan 31, 2022 9:16 am Erm...... surely where the caps are joined positive and negative they also need to be grounded as does the centre tap of the secondary winding of the transformer. Otherwise you won't get pos, 0, - negative power supply you'll get positive, half positive and zero volts on the bottom.
Why? How do the electrons know that the -ve terminal is the one at the bottom of the diagram?

In reality the amp input will either be explicitly grounded or will be grounded by plugging it into other kit. But there is nothing magical about 0v (as I have said a lot). Remember DQ has come from a background of using class III NVA kit, so ground is a flexible concept at best.
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#38 Re: Definitive Build

Post by Nick »

But it may be good to get a complete diagram of the power supply to avoid confusion. There will need to be one or two bridge rectifiers before those caps. I suspect there will be no center tap, but two secondaries with their own bridge rectifier. Which IMHO is a better way of powering a push pull power amp as it will deal with asymmetric signals better (doesn't create DC offset in the secondary of the transformer if there is 0v current).
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#39 Re: Definitive Build

Post by andrew Ivimey »

Yes a pair of bridge rectifiers would do it.
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#40 Re: Definitive Build

Post by ed »

Nick wrote: Mon Jan 31, 2022 9:23 am
Why? How do the electrons know that the -ve terminal is the one at the bottom of the diagram?
well in my well ordered view of the universe I reckon even electrons have a concept of home.
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#41 Re: Definitive Build

Post by Daniel Quinn »



This is power supply on my amps with 2 caps .
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#42 Re: Definitive Build

Post by Nick »

1, Don't wrap the link to flicker in a image tag as its not a image (I edited it for you)
2. One of the bridge rectifier terminals will be marked + and will be at 90 degrees to the others. Its important that the correct one is identified on the drawing.
3. You are so close to doing a circuit diagram, its so less open to misunderstanding
4. Ok, so you are using a center tap and one rectifier. Not ideal for reason I already said.
5. Your two extra caps are in parallel with the two you already have, +ve to +ve, -ve to -ve in both cases.
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#43 Re: Definitive Build

Post by pre65 »

That does not look right to me.

EDIT. Makes sense now. :oops:

Black & yellow are from the transformer secondary's and red/orange combined is the transformer secondary centre tap.

PS missed Nicks post whilst I was faffing about.

PPS I thought Dennis had posted some while ago about using two bridge rectifiers ?
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#44 Re: Definitive Build

Post by ed »

ps.jpeg
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#45 Re: Definitive Build

Post by Nick »

Yep, that will do it. If I remember, DQ first did use two, but something undetermined went wrong.
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