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paranoid06 29th November 2011 02:35 PM

Rod Elliot P3A Layout - Critics
1 Attachment(s)
Hi all,
I'm new to this thread...!
This is my 1st amplifier layout. I've been working with small layouts earlier.But this one seems to be a BOMB!
Any Suggestions related to placement of components welcome!

Thanks and Regards


Alfonz 29th November 2011 03:06 PM

1. Rotate R5 clockwise and get input part closer.
2. Put C+ and C- to the bottom of the PCB, it's necessary to have shorter track as possible.
3. Separate input GND from main GND (get a GND for input from filter caps).
4. You can rotate Q5 180 degrees clockwise, because Q5 doesn't need of any heatsink. U can rotate Q4 also.
5. The + - tracks must be bigger.

BTW is that Sprint Layout file?

paranoid06 29th November 2011 03:18 PM

Thank you! :)
This is an ExpressPCB file...I took the screen shot.
I like the pads of Cadsoft Eagle but don't know to use it :(
I don't like the pads of ExpressPCB but I know to use it....!

To make the component pad area bigger, I made rectangles around it!!


Alfonz 29th November 2011 05:20 PM

You can try Sprint Layout - got better adjustments and component library.
Great for beginners!

Or search in forum, there's a lot of treads about the legendary P3a.

paranoid06 30th November 2011 07:03 AM

1 Attachment(s)
I'm downloading sprint layout now and will let u know how it is :) Thanks for the suggestion.
I din't understand what to do with the ground. Can you please elaborate?
I've attached the edited layout.


east electronics 30th November 2011 08:00 AM

never post a lay out when its fresh made ... look at it again and again use the advice given ( except the ground issue ) and work on the concept ...

you will find a million other ways to make it better looking and better working

read the forum also .... there is loads of advice on people that tried before you and also there is a lot of advice given to correct the mistakes ..

your pcb will work but its very generic it has a number of things to be corrected

kalmara 30th November 2011 08:10 AM

I doubt his pcb will work, has to do at least 10 more revisions.

p.s. Where's the Q6 collector connected to again?

east electronics 30th November 2011 08:39 AM

kalmara is correct

ingenieus 30th November 2011 11:55 AM

Here is the original circuit, for those who are trying to work it all out:

60-80W Power Amplifier

Q9 should line up with Q7 and Q8 because thay all need to be on the same heatsink.

paranoid06 30th November 2011 12:14 PM

1 Attachment(s)
Thank you for your suggestions everybody, I've tried to edit the layout according to Alfonz's suggestions. Hope its better this time!

@sakis - what happens if the layout isn't up to the mark? Will it cause oscillations in the amp??
@kalmara - thank you for letting me know that! That was just something that cannot be avoided! And was out of carelessness.
@ingenius - Is it really necessary to keep them in a line? I was thinking of using U shaped heatsinks used for TO-220s

I've attached the edited layout.

Thanks and Regards

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