Re: Software for a beginner to design and learn about circuits with?

From: Kevin Aylward (salesEXTRACT_at_anasoft.co.uk)
Date: 12/01/04 

Date: Wed, 01 Dec 2004 11:56:38 GMT

mike wrote:
> Kevin Aylward wrote:
>> mike wrote:

>
>
>
>
> This is fundamentally wrong in my opinion, and
>> that of probably every educator known to man. If this were true,
>> there would be no lab work until 3rd year of uni. The best way to
>> learn is to do little bits of theory at a time complemented by
>> practise to reinforce that theory. A simulator is indeed *real*
>> practise, excluding the few % issues like parasitics. Too many here
>> are going, well because a simulator doesn't copy everything exactly
>> from the real world, then it is sadly lacking for real world
>> learning. This is very narrow minded. *Most* of what a simulator can
>> do is very good model of the real world. Spending several years doing
>> the "basics" before even getting
>> started on trying out the theory is quite daft.
>
> I do so enjoy reading your posts. You seem to get a lot more out of
> my posting than I wrote. I never said anything about how long it
> should take. Never said you shouldn't do bench work along the way.
> Point I was trying to make is to leave the simulator out of the
> picture until you have a basic understanding.

But I don't agree that all of what you state above is "basic" from a
beginners point of view. e.g. Laplace, Fourier.

I certainly didn't wait to lean that stuff when I was 11-14 building up
my guitar effects pedals.

>
>
> One would simply forget what one
>> first learned. To all intents and purposes, there is no practical
>> difference between examining ohms law and I=cdv/dt on the bench or
>> in a simulator. Your brain, eyes and ears are processing
>> essentially, the same information. There is only this vague
>> psychological issue that some have about it "not being the same".
>> Essentially, it is.
>>> Circuit simulation replaces the tedious VERIFICATION calculations
>>> that we used to do by hand.
>>
>>
>> Unfortunately, in a real design of 100s to 1000s of components, hand
>> calculations are impossible. Even a one transistor circuit has no
>> exact analytical solution.
>
> Who said anything about exact analytical solutions? I GUARANTEE you
> that I can do calculations on a design with 100s of components.
> I didn't say what calculations.

I know. You can do a few back of the envelope calculations, but to
really *understand* what's going on, it cant be done, without
simulation. Many claim they can, but they are usually lying to
themselves. Its hard to admit ones brain is not capable of understanding
all the details without trial and error. I don't have that problem.

>
>>
>>
>>> It does NOT replace the thought processes needed to design circuits.
>>
>>
>> It can do. This is the reality of how it works in the real world,
>
> Unfortunately, I think you're right and stated so further down in the
> original posting. The problem is that idiots with no understanding of
> the fundamentals stuff numbers into a simulator that may or may not
> represent their actual implementation. They trust the result and have
> no clue how to fix it if it doesn't work.

I agree. You need to have good overall understanding of what going on,
but not necessarily all the details. The details are what the simulator
will bring out, *iff* you know how and where to look.

>
> In skilled hands, a simulator with input that precisely models all the
> circuit elements including parasitics, layout, power supply coupling
> signal coupling, magnetic coupling, electrostatic coupling...the list
> is long...can be a very powerful thing.
>
> Anybody who starts their education with a simulator is doomed to
> failure.

I still disagree on this. Its a complement. As I keep saying, there is
still much a beginner can learn with a simulator, the fact that it
doesn't cover *all* things is beside the point. Its like using a damp
towel to get the worst of the wetness off of you.

>
> not
>> how we kid ourselves it is or should be. Yes, you need a good
>> understanding independent of simulations, however, it is simple
>> impossible to understand all of the nuances of a design without some
>> constructive trial and error on a simulator. Yes, most don't like
>> this idea, but it is the way it truly is. To illustrate. Consider
>> the design of a nuclear bomb. These require amazingly powerful
>> computers. Sure, they are run by *experts* , but even these 20 year
>> experts cant understand the implications of all of the equations.
>> Thery are simply too complicated. Or for example, colliding black
>> holes. There is not a chance to develop a *feel* for happens
>> *without* simulations.
>
> Your argument is seriously flawed.

Oh?

> Somebody sat down and scratched
> their ass for a decade and decided, "Hey, I'll bet if we could split
> an atom, we could get a LOT of energy...and we'd have to manage the
> reaction somehow...and Uranium would be a good thing to look at...
> let's go do some math.
> You seem to be suggesting that any idiot with a big computer could
> invent the bomb. NOT LIKELY!

There is no reasonable way that what I wrote could be interpreted in
that way.

. A simulator is pretty useless without
> input. I'd go so far as to say that a simulator is pretty useless
> with MOST unskilled input.

Not at all. A beginner will get lots of useful information from a
simulator. *Excluding* the obvious parasitics etc, the beginner can
learn *everything* *else* that a simulator does indeed do correctly. For
example, biasing up transistors, plotting waveforms etc..

Everyone here keeps ignoring the *numbers*. Sure, out of a possible 1000
things a simulator might do, maybe 10-20 of them will be erroneous when
tried on the bench. So what? *Most* of what can be done on the bench is
well covered, and that's what matters.

>
>>
>> Sure, I agree that without bench work there are many issues that one
>> doesn't get a feel for in a simulator, but *likewise*, without a
>> simulator there are *many more* things that you never get a feel for
>> by bench work. As I said, I've been there 10000's of hours on both
>> the bench and simulator. I can count countless things that I have
>> missed on the bench that the simulator showed.
>>
>>
>>> You have only to read the archives of this newsgroup to see
>>> countless examples where people stuffed random numbers into a
>>> simulator and came up with something that simulated, but was
>>> impractical, unrepeatable, or just plain sad.
>>
>>
>> But this is unintelligent trial and error. Intelligent trail and
>> error is another matter entirely. *All* design can be reduced to a
>> Darwinian process, i.g. replication of existing circuits, varying
>> such designs, and selecting the good ones. Whether this is done on
>> paper, in ones head (a Darwinian process) or on a simulator don't
>> much matter.
>
> I think you're exactly right. A designer without an understanding of
> the fundamentals is gonna be just as bad whether he does simulation or
> bench work.

That's correct. My point in this thread is that *most* of real world
electronics can be learnt with a simulator much easier and quicker. One
doesn't have to go through the trouble and expense of getting components
and instruments. Of course, the remaining few % of board level required
learning might take up 99% of ones time, but that's another story.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

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