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Old 26th December 2010, 04:35 PM   #771
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I forgot 470 ohm resistor beetwen pin 1 and pin 4 of LM311N
In .zip file you have changed layout with this resistor and pcb.

Conect two stars with short wire like "big" jumepr (this is your feedback)

Check board one more time before, if you find any error, tell me how I can fix it.

If anyone use PCB Wizard, I can send original .pcb file

Regards
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File Type: zip ucd amp.zip (133.7 KB, 740 views)
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Old 26th December 2010, 05:45 PM   #772
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A good PCB comes from understanding some basic principles.
A short remainder:
1. Current always flows in loops (kirhchoff's law)
2. Inductance of the loop is mainly dependant of the geometric area. You may understand a loop as a single turn solenoid, a big loop has pretty some inductance and open flux, I mean it becomes an antenna
3. If return current flows through a bottom layer plane, it flows directly under the signal on the top layer trace because of proximity effect. Therefore current loops related to bottom layer plane have minimum areas and all the inductances are reduced to absolute minimum.
4. Why we want to reduce inductance is because it creates resonant circuits with capacitances. When you get a resonance the way to kill it is by resistance (manipulating Q factor)
5. 10mm of a trace on FR4 board over a return plane has around 10nH.
6. TO220 mosfets have internal inductances of around 5 to 8nH, TO247 are much worse.
7. Control loops (gate driving) must be traced separate from power loops, whch exhibit high di/dt.
8. SMD parts have much lower inductances, this is ecpecially important for capacitors.
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Old 26th December 2010, 11:11 PM   #773
NMOS is offline NMOS  Germany
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Quote:
Originally Posted by darkfenriz View Post
A good PCB comes from understanding some basic principles.
A short remainder:
1. Current always flows in loops (kirhchoff's law)
2. Inductance of the loop is mainly dependant of the geometric area. You may understand a loop as a single turn solenoid, a big loop has pretty some inductance and open flux, I mean it becomes an antenna
3. If return current flows through a bottom layer plane, it flows directly under the signal on the top layer trace because of proximity effect. Therefore current loops related to bottom layer plane have minimum areas and all the inductances are reduced to absolute minimum.
4. Why we want to reduce inductance is because it creates resonant circuits with capacitances. When you get a resonance the way to kill it is by resistance (manipulating Q factor)
5. 10mm of a trace on FR4 board over a return plane has around 10nH.
6. TO220 mosfets have internal inductances of around 5 to 8nH, TO247 are much worse.
7. Control loops (gate driving) must be traced separate from power loops, whch exhibit high di/dt.
8. SMD parts have much lower inductances, this is ecpecially important for capacitors.

Hello, have redesign PCB, please check it, on TOP Layer have big GND

is it ok now ?
Attached Files
File Type: pdf Class D UCD BETA 27.12.pdf (68.4 KB, 655 views)
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Old 26th December 2010, 11:15 PM   #774
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Quote:
Originally Posted by darkfenriz View Post
A good PCB comes from understanding some basic principles..
Keep tracks short.
Leave as much copper on the pcb as you can especially the ground plane. Not only reduces impedance but saves the planet too.
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Old 27th December 2010, 12:05 AM   #775
Tom4s is offline Tom4s  Luxembourg
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Quote:
Originally Posted by NMOS View Post
PCB UCD 25.12.2010.pdf
With this thread being about bringing 25W to 1200kW, it's nice seeing such high activity on the 25/12!
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Old 27th December 2010, 07:40 AM   #776
akraj is offline akraj  Bangladesh
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Dzony988: I am using PCB wizard, Please post the pcb file.
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Old 27th December 2010, 07:41 AM   #777
akraj is offline akraj  Bangladesh
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Quote:
Originally Posted by Dzony988 View Post
I forgot 470 ohm resistor beetwen pin 1 and pin 4 of LM311N
In .zip file you have changed layout with this resistor and pcb.

Conect two stars with short wire like "big" jumepr (this is your feedback)

Check board one more time before, if you find any error, tell me how I can fix it.

If anyone use PCB Wizard, I can send original .pcb file

Regards
Dzony988: I am using PCB wizard, Please post the pcb file.

Thanks
Raj
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Old 27th December 2010, 08:01 AM   #778
voxac30 is offline voxac30  Slovenia
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Hi !

There are diferences in Schematics -Dzony had diferent supply for LM to original,-Dzony your amp is working can you send a parts list and schematic of your PS?. I think I will use your PCB for first project to learn how work such class d amp
Thanks
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Old 27th December 2010, 10:12 AM   #779
NMOS is offline NMOS  Germany
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Quote:
Originally Posted by Tom4s View Post
With this thread being about bringing 25W to 1200kW, it's nice seeing such high activity on the 25/12!

very cold, SNOW and ICE Storm outside, its better stay home and design PCB in this cold winter days...and enjoy sound in summer
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Old 27th December 2010, 02:16 PM   #780
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Is good this PCB?

Click the image to open in full size.
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