Laying out a PCB

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
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b1gtuna
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Laying out a PCB

Post by b1gtuna »

Thanks to this forum, I was able to draw up a schematic[1] for 3 way audio splitter using NE5534.
Following Wayne's suggestion, I have been trying to manually lay the board out. And surprise surprise it has been pretty difficult.

Some rules I thought I would stick to:

- One layer board. Apparently a lot of audio designs are done in a single layer(?)
- Keep bypass capacitors close to the IC
- Ground pour wherever possible

Even with these simple rules, it is hard to draw up a semi-professional looking design.

Problems I have:

- Better looking traces
- Thickness of the +-12V may be too small
- Output signals running through resistors R9-14 (couldn't route output left and right signals without criss-crossing them at one point)

It would be great if I can get some inputs. I can see myself designing more audio stuff, but analog circuit is actually pretty darn hard!

[1] viewtopic.php?f=6&t=751
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Speedskater
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Re: Laying out a PCB

Post by Speedskater »

Where does the power supply common connect to the ground pour?
Kevin
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JR.
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Re: Laying out a PCB

Post by JR. »

b1gtuna wrote:Thanks to this forum, I was able to draw up a schematic[1] for 3 way audio splitter using NE5534.
Following Wayne's suggestion, I have been trying to manually lay the board out. And surprise surprise it has been pretty difficult.

Some rules I thought I would stick to:

- One layer board. Apparently a lot of audio designs are done in a single layer(?)
Actually not so much these days. Back decades ago, and even Peavey's in house PCB process was single sided, but now most purchased PCB are run on a 2 sided process, so if you send out a single sided design they will probably just etch off the 2nd layer.
- Keep bypass capacitors close to the IC
- Ground pour wherever possible
The ground needs to managed with some kind of plan (think about the current flow). Even with a large ground pour, it will have a finite resistance so layout will matter.
Even with these simple rules, it is hard to draw up a semi-professional looking design.
Some here have been designing PCB for multiple decades.
Problems I have:

- Better looking traces
your traces don't look bad.
- Thickness of the +-12V may be too small
should be easy enough to make that fatter.
- Output signals running through resistors R9-14 (couldn't route output left and right signals without criss-crossing them at one point)
a double sided design might help...
It would be great if I can get some inputs. I can see myself designing more audio stuff, but analog circuit is actually pretty darn hard!
If it was easy everybody would do it. :lol:

JR
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dirkwright
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Re: Laying out a PCB

Post by dirkwright »

I use Pad2Pad. It's easy to use and they treat me well.

I do not use electrolytic capacitors for IC power supply bypass. Put two large electrolytics where the power connects to the board, and then use MLCC's at each power supply pin on each IC, as close to the pin as possible. 0.1uF MLCC is plenty for this chip.

I use a ground plane on both sides of the board. One side is ground return and the other is a shield (connected to ground at one point only).

good luck!
b1gtuna
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Re: Laying out a PCB

Post by b1gtuna »

dirkwright wrote:I use Pad2Pad. It's easy to use and they treat me well.

I do not use electrolytic capacitors for IC power supply bypass. Put two large electrolytics where the power connects to the board, and then use MLCC's at each power supply pin on each IC, as close to the pin as possible. 0.1uF MLCC is plenty for this chip.

I use a ground plane on both sides of the board. One side is ground return and the other is a shield (connected to ground at one point only).

good luck!
Does MLCC have advantage over electrolytic caps when used as bypass/decoupling caps? Other than the smaller size and form factor? Thanks for the input!
b1gtuna
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Re: Laying out a PCB

Post by b1gtuna »

The PCB is still on the way. Should arrive this week. In the meanwhile, I got myself some expensive capacitors from Digikey.
I am not sure if there is a point in using Nichicon's Muse caps for dc-blocking and by-passing, but oh well...
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mediatechnology
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Re: Laying out a PCB

Post by mediatechnology »

Does MLCC have advantage over electrolytic caps when used as bypass/decoupling caps?
Yes, and they are best used together.
An MLCC and an electrolytic bypass different frequency ranges.
The electrolytic will usually have much larger capacitance but as a consequence of that it will also have higher series inductance.
The MLCC has low series inductance.
At higher frequencies the MLCC is more effective than the electrolytic; at lower frequencies the electrolytic is more effective owing to its larger value.
The MLCC bypasses the bypass cap.

Whats the PC board gizmo in the pic?
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