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Old 17th January 2009, 09:43 PM   #1
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Default Parallel Bridge?

If I would like to parallel more than one bridge off a single secondary(s), would a .1ohm 5W at each bridge input work to alleviate any differences in input diode forward bias differences? Thanks for any inputs. -bg
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Old 18th January 2009, 12:30 AM   #2
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The resistor should be 0,1 to 0,3 times the forward voltage divided by the maximum current. 0,1..0,3*(Uf/I). And the diodes should only be used up to 85 % of their nominal rating.

The better solution is to use diodes with higher ratings and heatsink them.
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Old 18th January 2009, 11:25 AM   #3
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The resistor should be 0,1 to 0,3 times the forward voltage divided by the maximum current. 0,1..0,3*(Uf/I). And the diodes should only be used up to 85 % of their nominal rating.
PacififBlue,
Thanks for you comment. I can't disagree with you, but I don't want to redesign this PS. I need to make it work with less than optimal solution. What am I in for? thx. -bg
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Old 18th January 2009, 03:38 PM   #4
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Which diodes were you going to use? And how much current do you need?
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Old 19th January 2009, 01:01 PM   #5
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Default MUR860

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Which diodes were you going to use? And how much current do you need?
Current? Well, same as anyone who would like to play at "realistic" levels. However, I would be spreading what would typically be going to one speaker over 3 or 4 chs, woofer, mid-bass, mid, tweeter. That might change someday if my use changes. Thx. -bg
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Old 19th January 2009, 06:09 PM   #6
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Default Re: MUR860

Quote:
Originally posted by rgrayton
Current? Well, same as anyone who would like to play at "realistic" levels.
So, why do you want to use diodes in parallel in the first place? The only reason I can think of is to raise the current rating.
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Old 19th January 2009, 07:15 PM   #7
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So, why do you want to use diodes in parallel in the first place? The only reason I can think of is to raise the current rating.
Are you suggesting a single bank would handle 8ch? Well, here's a stupid reason: they came w/the kit
And maybe another one, I would be flexible as to application once my present passion for spkr dsn was quenched. From the blissful world I live in, I could deliver to any HT I could imagine. It never occurred to me the parallel bridge thing was an issue, so why not be prepared? -bg
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Old 19th January 2009, 09:15 PM   #8
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Default Re: MUR860

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Originally posted by rgrayton
Are you suggesting a single bank would handle 8ch?
How much current do those eight channels need? I. e. what is the rail voltage and speaker impedance or what is the nominal output power per channel?

And which diodes or bridge rectifiers do you have?
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Old 19th January 2009, 10:21 PM   #9
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How much current do those eight channels need? I. e. what is the rail voltage and speaker impedance or what is the nominal output power per channel? And which diodes or bridge rectifiers do you have?
Don't know how much current (like an off-the-shelf commercial box would not). The initial use for this would be for various spkr designs and wind up some day in a HT.
For diodes, MUR860 w/8 continuous and 16 pk, I believe. But, I think that would be heat sunk and that is not the case for me. thx. -bg
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Old 20th January 2009, 03:12 AM   #10
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RGrayton- I think you are on the right track, a simple dirty, ugly fix would be something like 0.1 ohm 5 W at each bridge input. I say "something like" because I don't know if 0.1 ohm is ok, or if you need 0.3 or 0.5 ohms.

Still I would recommend selling the diode boards and putting all those caps in parallel behind one large bridge. But your thinking may be acceptable to you; this is DIY we cannot tell you what to do and I certainly don't mean to criticize your effort.
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