[sdiy] PCB Design

[HARRY BISSELL]

I like large pads and traces, they allow for easy and robust modification
and repair. I use .020 for traces, 040 for power and ground. I use narrow
oval pads for resistors, caps, ICs on the top side and larger ovals on the bottom.
I allow one trace between IC pins (or two resistors side by side) on the TOP
side only (this minimizes solder shorts...).  See some examples of my layout
at www.wiseguysynth.com under "guitar synth". 

Coupling can be trouble in high gain circuits like the reset comparator in a VCO,
for example.  DECOUPLING caps are necessary. I always run power and ground to all
ICs and decoupling caps BEFORE I run anything else !  

See any archive posts by myself, or my twin Jim Patchell, on the subject of
decoupling. We are considered somewhat extreme, but I believe in cheap insurance !!!

H^) harry




----- Original Message -----
From: David Ingebretsen <dingebre at 3dphysics.net>
To: 'Synth DIY' <synth-diy at dropmix.xs4all.nl>
Sent: Sat, 2 May 2009 23:03:38 -0400 (EDT)
Subject: [sdiy] PCB Design


I'm taking my next step and want to take schematics I've found (not mine...
yet) from various sources and would like to turn them into PCB's. I bought
R.G. Keen's PCB Layout book from Small Bear, a very good read and have
searched other sources on the net but would like to ask this group a couple
of questions.

First, I purchased and will be using Target 3000!, (the medium version, 2
copper layers, 1000 pins/pads I added up some of the schematics I wanted to
do and this seemed to fit the bill without completely decimating my wallet).

1. How critical are coupling effects between traces and components? Target
will do an EM radiation analysis, but I've not seen or read that this is
critical for the type of circuits I'm interested it for my modular.

2. How critical is it to have some sort of large ground plane on the PCB?

3. Any hints, advice, rules of thumb, that will be helpful? Typical track
widths? Typical pad sizes? Anything else?

I followed the discussion a while back on PCB manufacturers and it was quite
helpful.

I'm really not thinking I'm going to be trying to make exotic, highly
optimized, many, many layer boards. I just want to avoid point to point on
perf board.

Thanks everyone.

David

David M. Ingebretsen M.S., M.E.
Collision Forensics & Engineering, Inc.
2469 East Fort Union Blvd. STE 114
Salt Lake City, UT 84121
www.CFandE.com

801 733-5458 Office
801 842-5451 Cell

dingebre at CFandE.com
dingebre at 3dphysics.net



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