[sdiy] Verniers for Patch Recording

[Czech Martin]

Ian, 
I think most people got your idea.
I also think that many people are interested
in finding old patches again.
I admit that your idea is cheap and it will work
for some people.

My eyesight is not so good, and I fear it won't get
any better. So *for me personally* it seems to be no sufficient
solution. Also I had/have always problems reading slide
rulers etc., I find it difficult to interpret the vernier
(even with better eyes). I also think that the 10 turn
dials are difficult to read.

Maybe other people prefer other approaches.

Perhaps larger dials are possible. More resolution, but also
more space.
There are knobs with a scale printed on them,
so the panel needs only an arrow (you can read
1.2, 1.4, 1.6, 1.8 and so on). These knobs are not cheap.
2.35 EUR each. See scale.jpg.

My idea of fine and coarse does of course not work.
Obviously the problem applies also to the coarse pot
which has also the most influence.

Perhaps a mixed approach is possible: the usuall scales 
and knobs for most modules, and a special atenuator
module that offers 10 turn, or large dials, or scaled knobs
or vernier knobs or digital pots.

The idea is that perhaps yoiu do not need high resolution 
everywhere at the same time.

If a standard level in a modular could be defined, like Juergen
proposed, many signal chains woul need no knobs at all, and if,
such a special 


Count.jpg shows a luxury version with good readblitiy.
My.jpg shows knobs I personally like the most.

Very good discussion on a important question.

m.c.


> -----Original Message-----
> From: Ian Fritz [mailto:ijfritz at earthlink.net]
> Sent: Mittwoch, 1. Oktober 2003 03:40
> To: Czech Martin; synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] Verniers for Patch Recording
> 
> 
> At 10:15 AM 9/30/2003, Czech Martin wrote:
> >That's why some analog computers have 10 turn pots.
> >Together with the counter knobs this will cost
> >20$ per dial, ouch!
> >
> >OTOH, for critical applications it is the only way:
> >Concentric dual pots would be cool, but they are not available.
> >Old measurement gear has often a coarse pot/switch plus
> >a "vernier" pot.
> >I used a 12 step switch "coarse" with 1% resistors
> >plus vernier pot for some purpose. The steps are not equal,
> >to my dismay.
> >
> >
> >Another source of error: some people have a couple
> >of modules of the same type. Resistors have 1%,
> >but the usual pots have a loose correlation between
> >angle and resistance. A 1/10 ratio could mean 1.0
> >on one module, but maybe 1.2 on the other.
> >
> >So, not only the type of module and all dials
> >have to be noted, but also the actual "number"
> >of the module that was used.
> 
> I think most people could manage this without too much trouble.
> 
> >But you are right, this unacuracy is the reason why
> >finding an old patch is near to impossible.
> 
> I think that 7-bit resolution on all your controls (except 
> pitch) would 
> make it possible.  But it doesn't sound like anybody really cares.
> 
>    Ian
> 
> 
> 
> 
> 
> >m.c.
> >
> >
> >
> > > -----Original Message-----
> > > From: Ian Fritz [mailto:ijfritz at earthlink.net]
> > > Sent: Dienstag, 30. September 2003 15:52
> > > To: Czech Martin; synth-diy at dropmix.xs4all.nl
> > > Subject: RE: [sdiy] Verniers for Patch Recording
> > >
> > >
> > > Hi Martin --
> > >
> > > At 05:21 AM 9/30/2003, Czech Martin wrote:
> > >
> > > >Depends on how good your eyes are.
> > >
> > > True.  Mine are just so-so. It also depends on how large the
> > > knob is.  I
> > > made a linear vernier about 5 cm long (corresponding to a
> > > typical small
> > > synth knob) and I can easily set and read the vernier at my
> > > normal reading
> > > distance.  It has a much coarser scale than I've seen on the
> > > old radio
> > > verniers. I did it that way to make it fairly easy to
> > > construct.  You could
> > > copy the image I posted into a graphics program and reduce it
> > > to different
> > > sizes to see how it works for your eyes.
> > >
> > > >I guess some control voltage pathes are more
> > > >sensitive than others.
> > >
> > > Right.  But I think If you have a complex patch you may still
> > > want to get
> > > all the parameters quite accurately to avoid accumulated error.
> > >
> > > >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.
> > >
> > > Well, I did mention that at the end of the post.  Myself, 
> I wouldn't
> > > consider that practical for every single control, but for
> > > some controls it
> > > would probably be necessary.  For example if you need to
> > > reproduce an FM
> > > patch, the frequency ratio needs to be very accurate.  
> The modulation
> > > amplitude I'm not sure about.  That could get tricky.
> > >
> > >    Ian
> > >
> > >
> 
> 
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