> If it were a program, I'd could start at the beginning and follow the
> flow keeping track of variables, like a debugger does

A program or circuit might not necessarily be that simple. There could
be "feedback" loops - the state of one part affects the state of another.
You could equate analogue voltages in one part of a circuit with variables
(eg a count) in an ISR. The voltage on the sensor in an alarm system for
example. Programs and circuits cover the range from menially simple
to mind-blowingly complex, but they are all based on principles
 
> I think I'm trying to do that with circuits and sort of my question is,
> am I doing this right, or is there a proper way that I haven't figured
> out yet?  Do you start at + and work your way to - ?

An important point here IMO is that analysing and designing are
completely different

For example I see other people's programs and think, oooh, I wouldn't
have done it like that, doesn't suit my style. Similarly with circuits,
although cost is often a factor that could affect how it is built (there is
labour, and ingenuity, associated with programming but copies are
essentially free). Smart programming can save materials too of course

Maybe a zener will do instead of a regulator, after the conditionals are
considered - is there enough power available to waste on a zener, is
the zener voltage good enough, should I buy that clearance lot of 10c
regulators ........

I've re-engineered prototype circuits that were built with OTS parts
and money was no object (primarily because the person who built
them didn't know enough to select better, he just wanted the job done)

When faced with a prototype to build, I don't often need to pull another
circuit apart to get started. I know how I would do it and take it from
there. Reading the datasheets / application notes for unfamiliar ICs is
always a good step

> Certain components and groups of components we know do various
> things. Like little modules (or subroutines or function libraries).  And
> that when designing something you know which of these modules to
> put where to do what

The program / circuit analogy mostly works, but is a little simplistic. It
could equally apply to fashion. A button is digital (worked by fingers
and has two states), a zip could be considered analogue. Trousers are
digital (up or down), dress length is analogue and could be considered
logically

IF dress length < X THEN undies = 1 UNLESS Britney AND tramp

> I just think I'm not looking at the big picture correctly.

What will come with experience is intuition. Then you can visualise a
concept and instinctively know whether it's feasible and how it could
be put together. You need to study working circuits, measure them,
make substitutions and so on. Theory is an important part of the deal
but hands-on familiarity with components that don't appear to behave
ideally is just as important. After all, customers want a practical
circuit that DOES the job, not a theoretical one that SHOULD have

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