Cheap Thumbwheel Switches

[harry]

Per request of J. Larry Hendry - a short treatise on hex thumbwheels  ;^)

at MPJA.com for $0.50 (2 digit)

There are obvious uses for these.
Use  1-2-4-8 resistors and get an attenuator that covers 16 steps.

Use equal value resistors and use it to set modulation paths to/from
modules.  Like send an LFO to VCO1, VCO2, VCF, VCA.  All possible
combinations of four things are available.  Or have the VCA "get" assignments
from ENV1, ENV2, LFO1, EXT... whatever.

Gang the two switches... so that you get the assignments above... like ENV1,
ENV2, LFO1, and the wiper of Hex switch digit 2... for four more possibilities.

I use DECIMAL (not hex) switches in my modular, to allow a four channel mixer
to select the outputs of ALL waveforms (sine, square, triangle, saw, sub octave
1 & 2,
suboctave fifth 1 & 2, noise...). These are in a 2x2 mixer, with crossfade. Then
I can
go from one combination of any two waveforms (individual levels) to any other
combination... or center the croaafade for a 4 input mixer !!!   This could be
done with
a hex scheme also...  (Got your ears on Dieter?... here's a freebee!)

Downside of thumbwheels...

You have to go through positions you may not want...
Worst case... 8 flips of the switch. That is one at a time... you cannot
just crank it fast.
Buy replacement parts NOW. When they wear out its really hard to find
an exact replacement that fits your panel perfectly !!!
Watch OUT for switching capacitive loads !  The arc they may draw can
damage the contacts and reduce life greatly !!!

Also note that MPJA has a ROTARY hex switch... it has inverse code (but no dial)

so it should not be too confusing. It looks like a dip rotary switch with a
metal shaft /
bushing.  Rotational life of ???

NOW class... what could you do with a rotary hex switch that can fit in a hole
of
(oh ... let's say) a Chris MacDonald "MiniModular"... by mounting the switch in
an unused "mult" position. The shaft is long enough to mount it THROUGH the
board...
and still put a knob on the outside.  ;^)

Homework due tomorrow. Class Dismissed !

H^) harry

Of course everybody should check Jorgen Bergfors "Bergfortron" which has
thumbwheels
in it for various functions.

Any more ideas ???

"J. Larry Hendry" wrote:

> > From: harry <harrybissell at prodigy.net>
> > Hey wow...
> > ON TOPIC what a concept.
>
> Be careful Harry.  Somone may drop a tube or BDD on your head.  :)
>
> > Check out the Hex thumbwheel switches at MPJA.com
> > They are only $0.50 each (for 2).
>
> I have always liked these little thumbwheel switches and have been
> looking for just the "right" application to include some in my modular.
> So, how about a discussion on the merits of thumbwheel switches
> as MMIs for modular.  Obviously, some applications might make
> a decent interface while others would just stink.
>
> One idea I had that is not fully developed is using them in a normalling
> scheme between modules or module functions.  Let's here some others.
>
> At the risk of showing how basic my understanding of this whole concept, and
> to have something DIY to post to support the "back on track" theme, I am
> including a link at the bottom to my VERY modest website.  There are two
> circuits there which are designed to be used with any 1-volt-octave VCO that
> has continuous tuning only.  I like octave switches.  This project developed
> around that preference.  It adds octave and other interval switching to any
> VCO.  There are two versions.  One provides 5 convenient shifts up and down
> while the other provide shift to any interval.  They can be used for on the
> fly jumping to intervals or transpose, or ??  I find when I have these
> intervals at my fingertips, I tend to layer my VCOs with more than the
> traditional octave or fifth intervals.
>
> The circuits are shown built on a MOTM protoboard (my modular is built to
> the MOTM panel format).  However, I now have PCBs available for $15 each for
> both of them.  That price is designed around a "break-even" strategy.  I
> could send the PCB artwork to anyone interested if you would rather roll
> your own.  But, I would have to check first with the person who did it for
> me since the layout is his intellectual property.
>
> Credit for the circuit belongs in two places.  First to the authors of books
> on op amps which I am just beginning to get a basic grasp of.  Second to
> Paul Schreiber who has answered 1000 stupid newbie questions of mine over on
> the MOTM list.  In fact, the output driver circuit was blatantly stolen from
> one of Paul's designs.
>
> To most of you, I know this circuit is simple as they get.  However, it is:
> a - DIY
> b - On topic
> c - handy
>
> Larry Hendry
> Thankful to all that contribute.
> Self proclaimed expert (by profession) on high voltage and mains.