Proper PCB layout?
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the_villain

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Hi. i was wondering what YOU as a DIYers think is a proper PCB layout - especially for headphone amplifier. Questions like:
How you route the input signals to the potentiometer?
Should I avoid routing signals under a toroidal transformer (power supply)?
Which are the elements that cause most interference?
How wide are yor signal an power supply wires on the PCB?
Thanks in advance?
 
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tangent

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Quote:

i was wondering what YOU as a DIYers think is a proper PCB layout


There are many heuristics, and a few outright rules, but most of all a layout is a balancing act. There is no absolute right way...everything depends on the tradeoffs you need and want to make.

If you look in the DIY links sticky post, you will find some relevant links. One that pops particularly to mind is part of the Analog seminar materials link; one of the electronic books has a chapter on layout issues, IIRC.

Quote:

How you route the input signals to the potentiometer?


As directly as possible, avoiding other signal and power paths.

Quote:

Should I avoid routing signals under a toroidal transformer (power supply)?


Of course, and also it should avoid coming near the sides. Toroids don't radiate much, it's true, but putting signals virtually in contact with the transformer is just begging for problems.

Quote:

Which are the elements that cause most interference?


Lots of things:

- EM radiation from magnetics (transformers, inductors)

- RFI radiation from noisy components (input AC, digital circuitry)

- stray capacitance coupling signals between nearby traces

- Large trace loops acting as antennas

Quote:

How wide are yor signal an power supply wires on the PCB?


It's a balancing act. Thick traces have lower resistance, but they take up more room and may crowd other traces, leading to increased noise pickup. Thin traces keep lots of room between the signals, but their resistance is higher, causing extra ripple and possibly damage to the traces. Also, if your traces are thin enough, the board won't be manufacturable, or you'll incur extra charges from the manufacturer.

Quote:

Thanks in advance?


Oh. Well, since you ask, definitely, yes, thanks are due in advance.
 
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