[sdiy] Block based design was: Favourite VCO designs

[cheater cheater]

David,
it's indeed very useful to break up your designs into blocks and this
happens in every discipline of engineering. Plumbers have their
different pipes, software engineers have functions, electronics
engineers have their functional units, production/processing engineers
have their what-have-you.

However it's not good to think of them as completely separate blocks,
since they can often negatively affect or even interrupt each other's
operation:
- an air bubble two stories above can make my tap make squeaky noises
when it's used
- two functions in a computer program could be interacting through side-effects
- two blocks in electronic circuits could be interacting through the
power supply
- two processing machines standing next to eachother could be
exchanging heat creating unwanted feedback in the control problem

Notably, programming is the only discipline I mentioned where you can
completely disable this sort of block interaction by use of a
technique called functional programming; sometimes you can do this in
electronics by using an optical interface, but not always.

Unit testing helps a lot; it's very useful in software engineering but
quite difficult to carry out in electronics since normally you'd have
special instrumentation where you just plug in the block and it blinks
OK or FAIL. However you can of course do a similar thing by the use of
general purpose apparatus and a checklist of tests; that's why blocks
are *such* a useful approach.

Being mainly a software engineer and less an electronics engineer I
cannot easily identify blocks in schematics like I would with
functional units in huge functions in program source code. That's why
for me it's much more useful if those schematics are indeed broken up
into blocks; better yet if the different lines going between blocks
are identified and described.

Just my 2c
D.

On Thu, Feb 25, 2010 at 00:54, David G. Dixon <dixon at interchange.ubc.ca> wrote:
>> ... I design circuits in blocks.
>
> This is one of the things I find very appealing about analog design.  It
> reminds me of the "unit operations" concept in chemical engineering (my
> professional training), whereby even the largest and most complex chemical
> plant can be broken down into a collection of discrete processing units,
> each of which is (more or less) easily understood and designed.  Without
> this capability, we wouldn't have many of the things we take for granted in
> the modern world (like plastic).  In a sense, electronics is even easier,
> since there is only ever one thing being pumped around the circuit.
>
> This is why my advice to a noobie looking to get into electronics would be
> to curl up with a decent book on opamp circuits (Coughlin and Driscoll is
> one of my favorites, but there are many good ones).  Opamps, in particular,
> lend themselves to this "processing block" approach.
>
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