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Chip Amps Amplifiers based on integrated circuits

LM3886 Servo Design
LM3886 Servo Design
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Old 6th June 2009, 10:30 PM   #11
Redshift187 is offline Redshift187  Canada
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Old 6th June 2009, 10:32 PM   #12
Redshift187 is offline Redshift187  Canada
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Old 6th June 2009, 10:33 PM   #13
Redshift187 is offline Redshift187  Canada
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Old 22nd June 2009, 10:03 AM   #14
Redshift187 is offline Redshift187  Canada
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I have ordered boards very similar to the ones posted here (I thickened the power tracks, etc). I also ordered a speaker protection kit from eBay with the following schematic: http://s700.photobucket.com/albums/w...t=SP0419-1.png

My question is, it appears that C3, C3' and C5, C5' are pairs of electrolytics placed in opposite polarity. Would it be better for me to just use a bipolar electrolytic in place of C3 and C5 and use a wire in place of C3' and C5'?
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Old 22nd June 2009, 10:53 AM   #15
peranders is offline peranders  Sweden
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LM3886 Servo Design
Quote:
Originally posted by aparatusonitus
A right way to protect an J-Fet servo opamp input which I've learned recently from ilimzn
This is not a good way because the servo can be extremely overdriven. It's better to have diodes between the inputs.
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Old 22nd June 2009, 10:57 AM   #16
peranders is offline peranders  Sweden
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LM3886 Servo Design
Quote:
Originally posted by Redshift187
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You have very thing power lines but it may not be a problem if the amp will go in light duty but for carrying 10 A peak it's not much.

My take with 95 um (2.5 oz.) copper
Click the image to open in full size.
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Old 22nd June 2009, 11:00 AM   #17
peranders is offline peranders  Sweden
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LM3886 Servo Design
Quote:
Originally posted by Redshift187
My question is, it appears that C3, C3' and C5, C5' are pairs of electrolytics placed in opposite polarity. Would it be better for me to just use a bipolar electrolytic in place of C3 and C5 and use a wire in place of C3' and C5'?
No!
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Old 22nd June 2009, 01:51 PM   #18
Redshift187 is offline Redshift187  Canada
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Yeah, I realized the power (and ground) tracks were too small, and made them much wider before I ordered the prototypes.

So, why is it a bad idea to replace those two electrolytics with a non-polar one? I've read that it's questionable to use two electrolytics reversed like that.
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Old 22nd June 2009, 09:30 PM   #19
aparatusonitus is offline aparatusonitus  Croatia
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Quote:
Originally posted by peranders

This is not a good way because the servo can be extremely overdriven. It's better to have diodes between the inputs.
We only need to ensure that the signal does not appear above or below servo opamp PSU voltage on his input. It is clear that will not appear at the + input which is earthed.
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Old 22nd June 2009, 09:34 PM   #20
peranders is offline peranders  Sweden
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LM3886 Servo Design
Quote:
Originally posted by Redshift187
Yeah, I realized the power (and ground) tracks were too small, and made them much wider before I ordered the prototypes.

So, why is it a bad idea to replace those two electrolytics with a non-polar one? I've read that it's questionable to use two electrolytics reversed like that.
The caps aren't reversed in any way. This is a very normal application for such parts.
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