On 20 April 2010 08:55, Olin Lathrop <olin_piclist@embedinc.com> wrote:
> Sean Breheny wrote:
>> While I agree that it is very dangerous to use simulation as a core
>> part of circuit design, sometimes it is unavoidable. For example, when
>> designing circuits involving feedback loops, I often use simulation as
>> a sort of calculator/Bode plot generator. I break open the loop and
>> feed signals in and see the relative gain and phase at the output
>> versus frequency. I can then check for gain and phase margin.

> If you already know what you're doing, this is fine. =A0Some filters can =
be
> very sensitive to part tolerances, which is easily overlooked with a
> simulator. =A0The simulation may work great, but the probability of any o=
ne
> physical realization working can be vanishingly small.

All models are wrong.
Some models are useful.

The power and flexibility of top modern SPICE simulations needs to be
experienced to be believed. Dealing with tolerances is often part of
their bag of tricks. There's no substitute for "doing it". But eg LT
SPICE often comes  a close second.

I haven't used SPICE "in anger" since I used to run it on a main
frame* about (agh) 25+ years ago BUT I intend to start doing so again,
based on recent recommendations of a friend who would technically give
Olin and I together a good run for the money (we'd probably be too
busy arguing to compete :-) ). Based on even that recommendation
alone, let alone the many others who say very very good things about
LT SPICE, it's probably time for Olin to join me in (again in my case)
dipping our toes in the SPICE water..

Question: Does it have  models for plug in breadboards and, that most
elusive of all circuit components, a human finger**?



                 ussell

* If you don't know what a main frame is be happy in the lack of
knowledge and don't ask :-)

** A finger is an indispensable part in eg making oscillators work or
making spurious oscillation s stop. If you could model that and make
and sell them you'd sell millions.

-- =

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