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Old 31st August 2010, 02:11 PM   #491
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The patent is for a class-D amplifier based on a phase-shift oscillator using the output switching ripple voltage after the low-pass filter as the source of the switching signal.
There are other post-filter NFB topologies but none that I know of have the elegant simplicity of the UCD concept.
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Old 31st August 2010, 11:12 PM   #492
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Quote:
Originally Posted by Tekko View Post
I bought a Lepai LP-2020 to see if that really is as prone to break as it appears here, i already modified a laptop psu for it, lowered the voltage from 19V to 13V.

As for the prototype, its not the design thats basically wrong, i believe the heatsink isent flat so that part of the fets dident have proper contact with the heatsink.
I'm not sure if Lepai have fixed things with newer revisions of their TA2020 based amp, but I've found that you need need to remove a diode that is connected to the Fault Pin of the chip. This has saved my TA2020 from burning out.


As for the heatsink, I find the existing one is ok but I unsoldered mine, then drilled out the mounting holes for the heatsink on the PCB. This allows the existing PCB to sit flat.

It's a shame that this amp has a few little bugs but I've found that they are easy enough to fix.
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Old 1st September 2010, 05:29 AM   #493
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I already have a few mod pland for this amp. Delete the diode and replace input lytics with little plastic caps, maybe replace the output inductors with two toroids with two windings on each.
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Old 1st September 2010, 06:10 AM   #494
qsa is offline qsa  Germany
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Quote:
Originally Posted by Tekko View Post
I already have a few mod pland for this amp. Delete the diode and replace input lytics with little plastic caps, maybe replace the output inductors with two toroids with two windings on each.

Hi Tekko

can you offer latest schematic with important changes for UCD amp like turn on delay / fast off ?
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Old 1st September 2010, 10:39 AM   #495
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I've posted it before, a few pages back:
Click the image to open in full size.
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Old 1st September 2010, 12:02 PM   #496
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Heres the newest version of my board:
Click the image to open in full size.

The modulator is now on a daughter board which also allows for testing of different modulators without changing the power board.
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Old 1st September 2010, 04:05 PM   #497
luka is offline luka  Slovenia
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And this is the way to go, also interference will be much lower from all high current paths
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Old 1st September 2010, 04:50 PM   #498
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And here it is fresh outta the bath:
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Old 2nd September 2010, 02:00 AM   #499
Eva is offline Eva  Spain
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The way is long but this is one step in the right direction
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Old 2nd September 2010, 05:49 AM   #500
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I'd like to replace all the through hole caps with smd ones so i don't have to drill and through plate some holes.
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