[sdiy] Breadboards

[Scott Gravenhorst]

Why I don't use simulation software and I _do_ use a solderless breadboard.

First, I make no arguement.  What Harry says is true of the faults.

However: The SSB is a physical electronic device and therefore dutifully
behaves as all physical electronic devices behave.  In other words, the
defects he lists can be accounted for because they are real physical
components.  Knowing the weaknesses is tantamount.

I do not use simulation software principally because in is _NOT_ physical
electronics and it's quirks can be vexing, even with the best and most
expensive simulators.  Yes, they can work, but no, not always and when
they don't it can be frustrating to understand why.  I will even
speculate that it's possible for a simulator to give a result indicating
a design works when it will not in a physical circuit due to limitations
in component simulation parameters (models).  While this may be rare, it
can happen.  

As for solderless breadboards, I use them for audio frequency use ONLY. 
And I mean no more than 20KHz.  This lessens the problems introduced by
row connector capacitance to some degree.  I would NEVER try to make a
200MHz oscillator nor if I could and it "worked", would I expect perfect
waveforms from it.  Maybe I just got lucky and bought the right kind of
SSB chunks.  Or maybe I'm careful and don't do things that would destroy
otherwise good ones, but I've never experienced rows shorted together nor
have I experienced other resistive connection problems.  Some things I
don't do is to force large diameter leads into the holes.  The wire I use
is modern telephone wire (not the older heavy copper "D-station" wire). 
I don't, for example, build a power supply or any power circuit on an
SBB.  In truth, the only designs I've had fail on SBB, failed because
they were bad designs or they were physically miswired.  This cannot be
blamed on anyone but me.

As always, your milage may vary.  My SBBs have never failed.



harrybissell <harrybissell at prodigy.net> wrote:
>Why I don't use breadboards - by H^) harry
>
>When I was in college, a good friend of mine designed a circuit.
>It was a theatrical light dimmer. Back in those dark days... many
>theatrical light dimmers were still mechanical, or motor driven
>rheostats
>or variable transformers. There were some commercial thyristor designs,
>but
>they were still in their infancy. (no... they didn't use gaslights back
>then :^)
>
>The design was a voltage controlled dimmer. 0-10V in for full range
>control.
>
>He got a commercial prospect to come and see the design. Of course the
>solderless breadboard chose that time to fail. He begged and pleaded...
>just
>five more minutes, it works I swear it does...  Well the guy gave him an
>hour
>to no avail.
>
>Two hours later, he found a wire that had snuck through a gap in-between
>rows
>and shorted.
>
>Two hours too late, too bad.  The opportunity was gone.
>
>LOL... we had a small breadboard at work.  When we were forced to 'clean
>the lab' I helped by offering to throw it away.  It was the ONE thing I
>was sure we would never
>miss :^P
>
>SMT will certainly obsolete the solderless breadboard. Maybe SMT is not
>ALL bad :^)
>(it will obsolete my favored technique, vectorboard and T42-A pins)
>
>If you like to use breadboards, that's cool. They were mainly used for
>teaching
>basic electronics in schools, so that parts etc could be re-used. Kind
>of like what they
>do with SPICE today.
>
>Bob Pease made the following points in his book "Troubleshooting Analog
>Circuits"
>
>1) Capacitance: 2-5 pF between adjacent strips "On a good day, only a
>wise engineer
>could plan a layout that all the capacitors, sprinkled throughout the
>circuit, wouldn't ruin"
>
>2) Long leads : make adding effective bypass capacitors close to a chip,
>difficult.
>
>3) Plastics : esp Nylon, on warm humid days insulation resistance
>suffers (too low).
>
>4) Contamination : Solder scrapes off the leads and can build up causing
>shorts.
>The adhesive makes it difficult to blow the scrap away with compressed
>air. (courtesy of Scott Bowman, Dublin CA.)
>
>Bob concludes...
>
>"I didn't even think about these solderless breadboards when I wrote my
>series
>because I see them so rarely at work. They just have too many
>disadvantages
>to be good for any serious work. So, if you insist on using these slabs
>of trouble,
>don't say that I didn't warn you."
>
>The breadboards are like SPICE in many ways. They let you try an idea
>quickly.
>In either case... I would not trust a SPICE simulation until I had built
>the real thing
>and compared the performance (to improve both the circuit, and the spice
>models).
>
>Be afraid... be very afraid...   :^P
>
>H^) harry
>
>
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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