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Class D Switching Power Amplifiers and Power D/A conversion

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Old 12th January 2008, 04:44 PM   #111
djQUAN is offline djQUAN  Philippines
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this thread seems to have turned into something that should be put in the powersupply design forum.

here's the latest waveforms.....

freq is dropped to 27.4kHz dead time is the same and gate drive supply is now driven from an aux winding.

edit: current draw at no load condition is now at around 400mA. that is the entire supply including a small fan, gate drive supply and PWM controller. only two LED's connected at the output via 10K resistors per rail.

Click the image to open in full size.

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and here's a closeup of the gate supply:

Click the image to open in full size.

TO-220 device is a LM317 which provides regulated 17.5V to the totem poles. you can see the aux winding going to one ferrite bead and four 1N4937 diodes mounted vertically arranged as a bridge.

gate supply remains regulated down to 11V input.
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Old 12th January 2008, 05:18 PM   #112
Eva is offline Eva  Spain
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Approved!
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Old 12th January 2008, 05:22 PM   #113
djQUAN is offline djQUAN  Philippines
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Quote:
Originally posted by Eva
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great! I thought I had to redo everything when you saw the layout.

at moderate levels, the waveforms barely change except for some tiny spikes here and there but nothing seems to go crazy. next on the list is power testing in the car.

BTW, the waveforms were taken with the amplifier module connected and running.
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Old 12th January 2008, 08:57 PM   #114
luka is offline luka  Slovenia
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Now this looks even better then before, good job. But what heat you will save with fest with that voltage, you will lose in diodes, but voltage drop on fets will be smaller...
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Old 13th January 2008, 04:16 AM   #115
djQUAN is offline djQUAN  Philippines
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well, I could have used better diodes but this was the best I could find here so I have no choice. besides, it seems to work well.
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Old 13th January 2008, 08:02 AM   #116
luka is offline luka  Slovenia
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I don't doubt their good working, just that they are way too big for this kind of operation, but as you said if this is only thing you can get...have same problems here

Now test in car? movie, movie...
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Old 13th January 2008, 08:38 AM   #117
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soon. just be patient.

I'm going to rebuild the entire setup of my car before this thing can go in so you'll have to wait.
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Old 13th January 2008, 09:58 AM   #118
djQUAN is offline djQUAN  Philippines
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it's just missing the bottom cover....

temp sensor already installed.

added a few SMD caps at the input terminals to reduce EMI

Click the image to open in full size.

almost finished case....(brown part is acrylic with paper cover still there)

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beside the old case....

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Old 14th January 2008, 07:46 PM   #119
MikeHunt79 is offline MikeHunt79  United Kingdom
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Hey, I'vd read up on how SMPS work, and now I know roughly how this works makes it more impressive...

I like that it is far smaller than your original set up... so are you getting nice solid rails now?
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Old 15th January 2008, 02:54 AM   #120
djQUAN is offline djQUAN  Philippines
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that's great....

this is what started it all for me.

I haven't done some power testing yet. the entire car setup of mine is out and I have to rebuild a new amprack. will update as to how it goes.
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