[sdiy] Block based design was: Favourite VCO designs

[David G. Dixon]

> it's indeed very useful to break up your designs into blocks and this
> happens in every discipline of engineering...
> 
> 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...

Yes, of course.  In process (e.g., chemical, metallurgical, petroleum)
engineering, sub-plants are designed as discrete blocks, but they must be
sized to play their proper role within the overall mass and heat balances of
the plant.  In other words, each block has a specific task to perform within
the whole, but can effectively be isolated from the whole for detailed
design, just like electronics.

The analogy between chemical and electronic engineering is remarkable.
Indeed, I would classify electronics as just another branch of process
engineering.  The major difference is that process engineers are mostly
concerned with the steady state, while electronics is mostly concerned with
the transient or cyclic response.  Where process engineering really
approaches electronics very closely is in the realm of process control.
Here, the engineer is mostly concerned with the transient response, and how
to control the plant to ensure proper and smooth functioning in the face of
various process upsets.  These upsets include delta functions (triggers),
step functions (gates), cyclic responses (waves), and noise.  Common process
control elements include sensors (keyboard), controllers (VCFs and
envelopes) and valves (VCAs).  Indeed, when you get right down to it, a
chemical plant is really just one big modular analog synthesizer!