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Old 28th October 2007, 01:14 PM   #1
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Default full bridge selfosc class d amp

Heres yet another new idea i have this is for a subwoofer amp.

schematic

What do you think ? Suggestions for improvements are welcome.
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Old 28th October 2007, 01:20 PM   #2
Eva is offline Eva  Spain
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This is not self oscillating.
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Old 28th October 2007, 01:42 PM   #3
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hum i dont see a carrier generator around
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Old 28th October 2007, 02:47 PM   #4
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Ok, I give up...
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Old 28th October 2007, 03:33 PM   #5
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Eva

"Ok, I give up..."

That was funny

Tekko

Your IC2 will probably have enough phase lag to cause self oscillation but it will be grossly non linear as it will be working in slew limiting mode all the time. I suggest that you add poles to IC2 and choose a model with high bandwidth for example AD8512.

I do not think that the driver will work well with one input low all the time? How where you thinking there?

Instead put a comparator after the OPAMP with dual outputs (one inverting).

You also need dual supplies for the OPAMPs (+/-12V).
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Old 28th October 2007, 03:52 PM   #6
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The input on a HIP4080 actually is a comparator.

I have seen schemes with poles on th feedback, add second set of resistors and place caps to ground, but im not sure if theres any benefit or any difference in doing that.

There is also LT1220, but all i have available at this time is TL082 and LF356.
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Old 28th October 2007, 04:11 PM   #7
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So heres one with dual output comparator before HIP4080:

schemo

I cant find the AD suggested in eagle.
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Old 29th October 2007, 01:23 PM   #8
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Im not trying out this thing on a breadboard.

Ill let you know how it goes.
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Old 29th October 2007, 08:33 PM   #9
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It dident work, the HIP4080 get hotter than hell.
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Old 30th October 2007, 10:49 AM   #10
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Tekko,

Put a reference on + input of the 4080 (12V/2=6V). So you do not need symetrical opamp supply( do not left +in of the comparator floating). Pay attention to voltage on Vdd/Vcc pin of 4080, it should not exceed 15V. TL082/072 can work here but AD8512 is better.

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