[sdiy] PCB design advice

[Jay Schwichtenberg]

Don't you love the smell of ferric chloride in the morning.

One of my pet peeves is bypass caps. Which I consider part of the PCB
design. IF you have anything (chips or transistors) that is switching
current or has very sharp edges or high frequency in it put in plenty of
bypass caps. Put the cap between the power source and the load. Do not put
the cap after the load.

You might have to put in guard tracks if you are running large voltages
around a board or have sensitive (high gain) circuits. These are tracks that
go to ground and isolate signals so you don't get cross talk.

If you do double sided boards don't run switching or sensitive signals
parallel on top of each other. You can get cross talk from this to. Usually
you run top side signals going either vertically or horizontally and bottom
side signals the other way. Basicly minimize the area they overlap.

Try to keep your input runs to op-amps and trannies as short as possible. I
usually put down inputs first and then grounds and try to do everything
else. Some people do grounds first.

Don't skimp on grounding especially is there is current involved.

Jay

> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Paul Schreiber
> Sent: Monday, February 23, 2004 7:25 PM
> To: M.A. Koot; synth-diy at dropmix.xs4all.nl; James Patchell
> Subject: Re: [sdiy] PCB design advice
>
>
> I suggest looking at the MOTM pcb layouts at:
>
> http://www.wiseguysynth.com/larry/motm/construct.htm
>
> Which, IMHO, are the best example of how to lay out. Rules are:
>
> 20mil lines with 12mil spaces
> 100mil power traces
> via size: 50mil/30mil hole
> pad: most are 70mil with 40mil hole (40mil hole makes it easy to
> *unsolder*
> mistakes). Some are 80mil pad.
> LPI solder mask (this is key: you don't pay any more, and the end
> result is 10X
> better than old-fashioned screened mask).
>
> Paul S.
> humble pcb designer