[sdiy] SPICE and Processors

[Scott Gravenhorst]

"David G. Dixon" <dixon at interchange.ubc.ca> wrote:
>> Paraphrasing Bob Pease: "It would take you 15 minutes to build that
>> circuit. Why bother with simulation?"
>> (that was on a seminar I attended in 2005)
>
>I would concur with this outlook.  I basically gave up trying to simulate
>audio with SPICE a few months ago.  Usually, just looking at the simulated
>waveforms is enough.  I often want to hear how a circuit will sound when a
>pot is rotated, and this takes forever in SPICE.
>
>Most analog circuits are easy enough to breadboard.  Since I etch and drill
>my own boards, and since most analog circuits are actually easier to lay out
>on pcb's than on solderless breadboards, I often just build circuits and do
>final testing on the prototype.  I find that it is usually the presence or
>value of small capacitors (<1 nF) which must be altered in the final design.
>SPICE doesn't always simulate the effects of small capacitors very well, and
>their effects are often different on breadboards and pcb's.  It is easy
>enough to put extra pads and connections on the board for them.
>

Same here, in fact, I've never simulated anything at all.  I'm sure it's a great tool for
some/many things though.  

I use a solderless breadboard, an oscope to see waveforms and an amplifier to listen to
it.  I adjust component values as needed on the breadboard and if/when I'm satisfied, I
build it up on stripboard.  One thing about the "try it" method is that sometimes a
circuit will do weird or perhaps unintended stuff that's interesting.  Those things may
look wrong in simulation, but could actually sound interesting.  If you ditch the project
idea because of a simulation or if the simulation gave incorrect output for some reason
or another, you might miss out on something cool.

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
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