[sdiy] Verniers for Patch Recording

[Andre Majorel]

On 2003-09-29 22:50 -0600, Ian Fritz wrote:

> One of the most frustrating aspects (at least for me) of modular analog is 
> the great difficulty of reproducing patches after they have been torn 
> down.  A hybrid system where control parameters can be saved on disk drive 
> solves this problem, but at the cost of requiring a fixed architecture plus 
> interface construction and programming.
> 
> While thinking about this today, it occured to me that it might not be too 
> difficult to read knob positions quite accurately using a vernier 
> technique.  I'm talking not about mechanical gear-reduction verniers, but 
> rather simple scale verniers.  I've seen these used on old radios and lab 
> instruments but never on a synth.  They are also used on inexpensive 
> (non-dial) calipers, which are surprisingly precise.

Clever. But with a simple deskjet printer, you could print an
ordinary scale with 5 subdivisions per division (i.e. 1/50
precision) and that seems good enough for me (+/- 1%).

If it's a critical parameter, it might make more sense to write
down not the physical setting of the knob, but the actual
result. For example, by using a frequency counter or DVM on the
output of the module. This is more accurate and immune to
long-term and short-term drift.

I think it was Charles Twist who mentioned at the last meeting
making generic panels that just output CV. With that sort of
architecture, saving and restoring patches would be possible. Of
course, then you'd have to have a digitally controlled matrix
too.

-- 
André Majorel <amajorel at teaser.fr>
http://www.teaser.fr/~amajorel/