[sdiy] ground & power on pad-per-hole solder breadboard

[Ian Fritz]

On my latest tri VCO I worked a bit on eliminating switching spikes from
showing up where they weren't wanted. What I ended up doing was running
separate power supply lines for different sections of the unit and using
ferite beads for isolation between them. Sort of a middle ground you might
say.

  Ian


----- Original Message -----
From: "Jim Patchell" <patchell at silcom.com>
To: "Kenneth Martinez" <kmartinez at bency.com>
Cc: <synth-diy at node12b53.a2000.nl>
Sent: Monday, May 14, 2001 7:55 AM
Subject: Re: [sdiy] ground & power on pad-per-hole solder breadboard


>     Grounding is almost more of an art than it is science.  At the very
> least, you are headed in the correct direction.
>
>     Creating a star connection on a PCB can be a big problem, because it
> takes up lots of space.  In general, you only need a star when you a
passing
> "significant" amounts of current in the traces.  The deffinition of
> "significant" is difficult to pin down, because, it depends on the
> situation.
>
>     Example of insignificant current: Current flowing into or out of an
> op-amp input.  Even in bipolar parts, this current is down in the nano-amp
> range.  These currents will not cause any significant voltage drop.
>
>     Example of significant current: Current flowing  out of the ground pin
> on a 555.  Even worse, it is not constant.  Another example of significant
> current is the current flowing out of the ground pin of most logic chips.
>
>     The main problem that drops in your ground may cause is when there is
> something that can use that voltage as it's input.  Sometimes finding out
> how these signals are being amplified by the circuit can be difficult.
>
>     Also, another aspect to all this is proper bypassing, to get rid of
the
> voltage spikes.  To properly bypass the current on a chip, you need to
> provide the shortest path possible between the bypass capacitor and the
chip
> being bypassed.  This, for the most part, can be difficult to do because
the
> power supply pins are generally positioned to make it difficult to put a
> capacitor directly accross the pins.
>
>     Anyway, this is a very big subject.  I am sure others will add their
> thoughts to this as well.  People who specialize in EMC compliance (and, I
> seem to recall we have a few on the list), would know a lot more about
this
> subject than I do.
>
>     -Jim
>
> Kenneth Martinez wrote:
>
> > I started soldering a vco on a solder breadboard with a copper pad per
> > hole...it doesn't have any copper ground or power busses, but I aligned
> > the ICs and components so that leads could be connected to ground by
> > soldering them to wires running in straight lines down the board between
> > the rows of ICs and components, and then connecting these ground lines
> > at the edges of the board.  For power, I'd planned to "daisy-chain" the
> > + and - supplies for the 5 ICs, connecting IC1 to the board's power
> > input, connecting IC2's power pins with short wires from IC1's power
> > pins, etc.
> >
> > I'm wondering now if it would make any difference if I used a star
> > arrangement to connect each IC directly to the board's power input?  And
> > would it be better to run separate ground wires from some or all
> > components to a central point instead of connecting them to those wires
> > running down the board to simulate ground busses?
>