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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th November 2003, 08:42 PM   #491
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Default Hi all, something about amploiD with PCB's.

http://amploid.narod.ru/article.htm
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Old 9th November 2003, 08:16 PM   #492
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Hi IVX, the translation of the text was bad for me. Is Fig. ABD a substitute for DT circuitry?
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Old 10th November 2003, 08:57 PM   #493
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Hi subwo1,
aha.. not only my English bad so much, but your Russian is even worse. :-) Actually in this article.htm i wrote about some my experiments at 1995 - 99. (the earliest extremely stupid and 28 irf mosfets have gone to smoke!) Regarding the fig. ABD - for that moment I didn't see _crest_lt_scematic, but made it for safety minimization Dead Time as well. However had more EMI problems with FM radio, and I have thrown this approach.
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Old 11th November 2003, 08:00 PM   #494
subwo1 is offline subwo1  United States
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Thank you, IVX, for your explaination. It was very interesting.

Yes, my Russian is so bad that I cannot read a single word of it
Best Wishes.
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Old 21st January 2004, 04:57 AM   #495
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Arrow Commentable Thoughts

THATS REALLY A EXCELLENT CLASS-D DIYING!
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Old 21st January 2004, 06:13 AM   #496
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DEAR SSANMOR

In ur amp u have devised 2 circuits in frontend section, one is using opamps and second is using MAX chip .
I want to know that which configuration gives the best results??
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Old 23rd February 2004, 01:30 PM   #497
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Cool Just tested my new Class D Amp

Today was the day of the big testrun... after some adjustments, it's really working nicely.

This is actually my first post to this forum, but I've been following it quite a bit.

I'd really like to thank Circlotron for his description of his BCA-Amp earlier. It was a great help for my design! I hope you read this...

But now to my amp, if anyone is interested. My plan was to build a powerful Class D amp for my subwoofer. I already built Elliot's Sub-Preamp, that compensates the subresonant response of closed subwoofers. Due to the significant boost of subsonic frequencies down to 10Hz, serious power is needed to maintain a linear response.
After experimenting with different modulation techniques, I read Circlotron's posting about his BCA-Amp, and I realised that this (patented) principle would solve my problems at the zero-crossing.

To make it short, I just finished building the amp on Veroboard, using a LF347N Quad-Opamp to generate 250kHz triangle waves, a KA319 Comparator for PWM generation, and in the power stage, 2 IR2112 Hi and Lo MOSFET drivers, and 4 BUZ11. The Power stage is a full bridge (4 MOSFETs, 4 torodial chokes, 220mH, and 100nF, as filters). The whole thing (2 small pieces of veroboard) is not even a handfull.

I can't really measure THD or S/N, but checked with an Audio Generator and an Oscilloscope. The output really looks nice, a cute sinewave, without visible deformations, even at full power (shortly before clipping). Lacking a good powersupply, I only could drive it with 30V (2Amp DC), which gave me an almost-30V-peak sine into 8Ohm load resistors, hence ~50 Watts RMS. The resistors got fairly hot, so I cooled them in a glass of water (which also got fairly hot after a while...). The MOSFETs were merely impressed. They don't even have a heatsink, and just got a bit warm. The freewheeling diodes also didn't have a problem. I think there is much more potential...
I should mention, though, that it only has a linear frequency response from 4Hz to 5kHz. This should be sufficient for a subwoofer, though. I'm going to experiment a bit, to make it full range (for my next project). Anyway, except for the missing high frequencies, what I could hear up to now through my speakers didn't sound to bad. No noticable distortion, and a powerful bass response.
If anyone is interested, I can try to update my schematic (most of the design process happened with a soldering iron... and post it. And maybe also some pics...

Cheers

Felix (sfx)
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Old 23rd February 2004, 04:30 PM   #498
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Quote:
If anyone is interested, I can try to update my schematic
hi Felix,
i'm already interested, please post schematic etc.
BTW, THD,IMD,S/N,FREQ.RESP is quite simple to do measurement by PC sound card.
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Old 23rd February 2004, 11:59 PM   #499
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Default Some pictures

Hi IVX,

Haven't had time yet to finish the schematic. But good news are, I have some pictures for you

http://syseng.anu.edu.au/~felix/iar/Projects/Thunderball/

The schematic will follow soon...

Which software do you use to measure THD, S/N, etc.? I used my soundcard already to measure the frequency response (spectral analysis, i.e. FFT of white noise) of my speakers, but haven't found a software yet that could do all the other measurements.

Cheers

Felix
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Old 24th February 2004, 06:08 AM   #500
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