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Class D Switching Power Amplifiers and Power D/A conversion

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Old 6th November 2009, 12:02 PM   #1
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Default D amp runing Cool for BASS car !!!

Before.... forgiven my errors write... im not very good in english.

Runing and wave forms!!
Sugestions, crytiques and coments !!!

Frequency amplifier : About 350 Khz, you can see in the pictures.

Supply: +/- 46V (SMPS for 12v car )

amp. frequency response = only for bass ( crossover active , 120hz).

load min: 2 Ohms !- I belive what i got 800 Wrms !

dead time= res 2.2k - cap 22pf = i think 48ns

the sound is very stronger and powerfull !!!

pictures = waveforms to
* In before IR gate driver (pin 10 and 12) ;

* after IR gate driver (pin 1 and 7) ;

* Out mosfet powers ( Before LPF );

* Package of car amplifier, amp and power supply inside... dont ask to me, how i got !!!! HuahUasHsaUAh

*AND Filter... i make this, with FLYBACK transformer (of CRT television) and wire... of course !!! no calcs, only turns and tests !!! ahh.. i take 1 meter and .... make this !!!

MY AMP really runing very good... i use in my car, play with speaker BRAVOX, Endurance 2k - 750Wrms and... i think that i disassemble my car !! AUHSUhauhuhHAUHSHUHAShuah

So... please if possible ... coments and help me !!!

thanks for Diy Audio !!! Fumiga from Brazil !!!
Attached Images
File Type: jpg IR in 1.jpg (184.8 KB, 529 views)
File Type: jpg IR out 1.jpg (180.7 KB, 499 views)
File Type: jpg out bf filter 1.jpg (175.1 KB, 480 views)
File Type: jpg pack.JPG (143.2 KB, 483 views)
File Type: jpg filter.jpg (53.5 KB, 468 views)
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Old 6th November 2009, 03:40 PM   #2
luka is offline luka  Slovenia
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800w with +/-46v? a bit hard, unless it is full bridge, which I think this one is not
Good job anyway, do even more work on this setup, you could get really nice amp out!
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Old 6th November 2009, 06:44 PM   #3
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i forget to say.... is Half bridge !!
and load impedance is 2 Ohms, so... minimun load , maximun power... and ... i not check if really 800w ... but i belive that is very near !!!

thanks Luka !!! i very happy with results ...
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Old 6th November 2009, 07:31 PM   #4
Eva is offline Eva  Spain
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Congratulations, but gate waveforms don't look clean and they probably become much worse when the amplifier is sinking or sourcing a significant amount of current, resulting in reduced reliability and electromagnetic interference. You have already gone quite far, but much work has still to be done.

For output coils consider toroids of -2 material from micrometals.

btw: +/-40V on 2 ohms are 400W rms.
I use to feel like the small child in The Emperor's New Clothes tale

Last edited by Eva; 6th November 2009 at 07:34 PM.
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Old 7th November 2009, 02:12 PM   #5
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Eva..... please help me !!!

How i can meter the power of amplifier ??

do you can post , some formulas, or methods of verify this ???

so... if i have +- 46v in supply ... and the amp has 90% efficient, if in the out of speaker, i got , near of 40Vrms ... right this ???
(1khz continuos by wave form generator )
40*40= 1600 / 2(min. load) 800 Wrms


Thanks for all and diy audio !!!
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Old 7th November 2009, 08:02 PM   #6
luka is offline luka  Slovenia
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45 + 45 * 0.353535 =31.8Vrms
(31.8V)^2 / 2R = 505Wrms

This is best case scenario
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Old 10th November 2009, 10:57 AM   #7
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you have to measure voltage rms at 2 ohms resistive load ,using scope you will see that the voltage before clipping 0.707 x 45=31,5vrms.31,5 . 31,5=992,25/2=496,1 as said before,in the best case.See
Eva said a very impotant point about output filter core material type 2 ,is the easiest way.Also search for decoupling and lay out .Also check your dead time mainly at high temperature.
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Old 10th November 2009, 10:38 PM   #8
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how a can meter the power RMS ???

by power supply ??? and i cant calculate the dead time correctly, put some formulas ??

the amp runing cool, but i dont know how works correctly. i'm study of High school, tecnology of industrial automation.

and i work with audio amplifier. well, if somebody it will help me..

i need help to calculate mH and A for Lpf filter, relative to power.

ex: 100w RMS ... how i need in the power supply , in volts and amp ???

i will be grateful , and forgive me for bad english...
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Old 11th November 2009, 07:23 AM   #9
luka is offline luka  Slovenia
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you could from supply, but that would be input power
what I would do, it put sine wave on load, resistor or reactive
measure voltage, measure current and you have power

more basic would be, to measure voltage on resistor and calculate current and power

About your example: it depends, you can get 100w rms with high voltage, or high currents, and in D amp both (high amp, seconday voltage, while having low impedance on output), but input of smps will draw always more then you put out, so if you somehow get, that you are puting out 100w from amp, but only 80w on input of smps, you did something wrong in your measurements
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Old 23rd January 2010, 12:16 PM   #10
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How i calculate the RMS power and Eficient of D amp ???

i build a new amplifier, with +/- 65v in power supply - 60khz (SMPS)

and 230khz the frequency of amp, load min 2 ohms.

its runing very best, cold and range frequency response is very good (full)

the soud is very LOUUDEEERR !!!

i use FOUR 3-way system, and... play so louder !!

now i need to calculate , eficient and wrms!!!

thanks !!!
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