Stereo LM3886 amp who wants to be mono! - Page 2 - diyAudio
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Old 31st December 2002, 05:02 PM   #11
ppl is offline ppl  United States
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MWP> Wow i am impressed with your amp are you trying to give Jeff Rowland a run for his money.. Hee... HEE.. Heck i was impressed with just using two bridged Pairs for a great 60 to 100 watt Per Ch. Amp for my PC. but heck your Beast is way Cool. Is that from the BPA 200 app note?

Skinny Boy> I was refering to whitch one of the several Bridge Circuit configuations available for this and other Power Op Amps some use the method that MWP is sugesting others tap off the Output of one and feed into the input of the Other and several others are used for this as well. The PM 21 as on the Link above uses MWP's method and is the one i also used. The Rane MA-3 also uses a LM-3886 but not in the Bridge mode. What a popular Chip National semiconductor has.
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Old 31st December 2002, 06:15 PM   #12
Gabster is offline Gabster  Canada
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MWP, what would be a sufficient capcitance for each channel? I built the amp following an article in a magazine (can't remember which one) and if I remember well, I've doubled the capacitance because...well I don't really know! At that point, that was my first amp and seeing people around stuffing as much caps as they could in their amps, I thought that was the way to go for any amp.

About your amp, is it 220WRMS per set of 2 bridged LM's? Meaning a total power 1760WRMS? If yes that's amazing and I would like to see the schematics and more inside pics.

ciao,
Gabriel
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Old 1st January 2003, 09:54 AM   #13
MWP is offline MWP  Australia
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Yeh, thats 8 * 200W which does give 1760W.
BUT... there is no way the 2*500VA transformers in there will supply enough current for that power output.

Its a home theatre amp, not a PA amp... full power out af all the channels at the same time will never be needed.

As for cap size... do some calculations. Every different application requires a custom power supply.
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Old 3rd January 2003, 05:41 PM   #14
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Hi, been watching this thread for a while, and i must comment on your amp Gabster, really NICE WORK!!!

But! since I'm a very stupid person and don't understand the pdf. file ppl posted, can someone please point out to me were I can find the curcuit for bridging those LM3886 chips. I know I'ts in the data-pages from Nat. semi. but I'm to dumb to recognize it when I see it

Apparently you have to invert one chip and then connect them togheter somehow, but I never understood how that is done.

Cheers!
Chris
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Old 3rd January 2003, 06:22 PM   #15
Gabster is offline Gabster  Canada
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Hope this help. The transformer is a 2x22VAC (400VA).
Attached Images
File Type: jpg 3886.jpg (83.5 KB, 2007 views)
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Old 3rd January 2003, 06:30 PM   #16
joensd is offline joensd  Germany
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Quote:
But! since I'm a very stupid person and don't understand the pdf. file ppl posted, can someone please point out to me were I can find the curcuit for bridging those LM3886 chips. I know I'ts in the data-pages from Nat. semi. but I'm to dumb to recognize it when I see it
Christian, the application note is called BPA-200.
Itīs here BPA-200

Regards
Jens
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Old 3rd January 2003, 09:19 PM   #17
Nicke is offline Nicke  Sweden
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Quote:
Originally posted by Christian
But! since I'm a very stupid person and don't understand the pdf. file ppl posted, can someone please point out to me were I can find the curcuit for bridging those LM3886 chips. I know I'ts in the data-pages from Nat. semi. but I'm to dumb to recognize it when I see it

Why donīt you look here:New application note

Nicke
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Old 4th January 2003, 05:44 AM   #18
MWP is offline MWP  Australia
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Quote:
Originally posted by Nicke

Why donīt you look here:New application note
Eeek, a new one... how long has that been available?
Thats 3 versions of that app note i have now.
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Old 4th January 2003, 10:53 AM   #19
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Hey Gabriel!! Thanks a lot!!
Finally got it now. So basically, you just run one chip with the signal on the (-) input and then connect both chip-outputs to each lead on the speaker.

Best Regards!
/Chris
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Old 4th January 2003, 11:37 AM   #20
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Does anyone have a PCB layout fora bridged AMP?
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