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Old 25th November 2011, 12:48 PM   #11
AndrewT is offline AndrewT  Scotland
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Could that 10r be a R//L on the output?
I consider that the wrong place to locate the L.
If I am interpreting the layout correctly, then that 10r has nothing to do with keeping the Signal Return separate from the Power Ground.
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Old 25th November 2011, 05:22 PM   #12
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There is a R C on the output but there is also another 10 r in series with the output . There is also a 10 R seperating the signal return . then there is also the 10 R i have marked

Last edited by madtecchy; 25th November 2011 at 05:24 PM.
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Old 25th November 2011, 05:23 PM   #13
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This one
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Old 25th November 2011, 05:28 PM   #14
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Hi Andrew . My cogs are turning a little slow today. i now understand you are saying the 10R i have marked is the R in the R L . The L is missing.

regards Ian
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Old 25th November 2011, 06:10 PM   #15
jcx is offline jcx  United States
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I would still see what swapping + pwr and gnd looks like

you would have to route V+ between V- PS cap pins but you probably have the room - even if you have to "neck down" the trace as it passes between the pins


the gnd at the board entry is about as "clean" as it can be and should be the signal gnd ref - unless you put a diff receiver cirucit on the pcb to allow a completly separate signal gnd
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Old 26th November 2011, 03:35 AM   #16
yatgai is offline yatgai  India
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Thanks Anderw for the detailed reply

Yes the horizontal 10R is wound over to form inductor L, missed to put L in the name

Pwr traces are 4mm wide at arrowest, traces to pin 9 & 10 are 1mm thick will they be enough ?

I will modify layout not to have bends at right angles

Thanks to all

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Yatin
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Old 26th November 2011, 04:32 AM   #17
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Default One more detail . . .

It looks like the board extends beyond the back row of pins too far to allow mounting the chip to a heatsink. According to NS's data sheet you have 4.3mm from the center of the back row of pins to a line parallel to the back of the chip. See the 1st picture.

Also, keep in mind that if the copper goes right up to the edge of the board, the copper will be exposed. It looks like your negative rail goes right up to the edge which will be against the heatsink.

It seems kind of late now, but you can probably get away with using a heatsink which sits on top of the board, like the Ohmite RA-T2X-64E (2nd picture). This allows you to put your chip anywhere you want on the board. That's what I'm using right now. I'm using +/-25V rails, driving 4R speakers and I've never had overheating problems.

Good luck.
-Byron
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Old 28th November 2011, 03:31 AM   #18
yatgai is offline yatgai  India
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Default Heat Sink

Thanks Byron

The back trace on the board is 4mm from the back row of 3886

The intended home made heatsink is PCB mounted and Heatsink is screwd to the enclosure.

Regards

Yatin
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Old 28th November 2011, 05:44 AM   #19
gootee is offline gootee  United States
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C1 and C2 are too far from the chip's pins. I would remove the "stub" that comes down to C1 and extend the gnd trace toward the chip, instead, then turn C1 90 degrees and put it right next to the chip. At the same time, move C2 upward toward where C1 was, so it's in line with the pin it connects to, and as close as possible. A millimeter or two makes a difference, with those small-value capacitors. If possible, put them underneath the board, so they can be connected RIGHT AT the power pins.

Your main smoothing caps, C6 and C8, would also be better if placed as close to the chip pins as is practical. There is room to easily move them a lot closer than they are.

I would also minimize the spacing between the power and ground traces.

It would probably enable the design to be better and much easier to implement if you just used a two-sided PCB but left one side almost all unetched, for a ground plane. You might have to make short traces to get out from under certain components, like the large caps, to be able to solder on the top side ground plane. But it should still be much better and much easier to lay out. You would have to etch or otherwise remove a little copper on the gnd plane side, from around the component-lead holes to the other side. But that would be simple enough.
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Old 28th November 2011, 08:21 PM   #20
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Gootee, is this what you mean for the C1, C2 caps?
It's done in Eagle, and I can post the files here if the layout is ok.
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