[sdiy] Verniers for Patch Recording

[Czech Martin]

Depends on how good your eyes are.

I guess some control voltage pathes are more 
sensitive than others.

What about a range switch together with the pot?
This will virtually increase the resolution of the pot.
It can be a 2 position, a 3 postion, or the usual
12 position switches depending on application.

m.c.


> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Ian Fritz
> Sent: Dienstag, 30. September 2003 06:50
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] Verniers for Patch Recording
> 
> 
> Hi folks --
> 
> 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.
> 
> Has anybody ever thought about doing this?
> 
> For those not familiar with scale verniers, they incorporate 
> two scales -- 
> the usual one on the panel and a second one on the skirt of 
> the knob.  The 
> two scales have different spacings, and the dial reading is 
> interpolated 
> between dial marks by noting which marks on the two scales 
> are closest to 
> alignment.  I have put up a simple illustration of how this 
> works on my site:
> http://home.earthlink.net/~ijfritz/xfer.htm
> 
> By playing around with some paper cutouts I have convinced 
> myself that 
> 7-bit resolution could be achieved this way, even with small 
> (3/4 inch 
> diam) knobs.  This technique will not work for parameters (filter 
> frequency, e.g.) where coarse and fine control pots are used. 
>  It might be 
> necessary to use a switch for the coarse control in this case.
> 
> Thoughts?
> 
>    Ian
> 
>