[sdiy] joystick pots

[harry]

Hi Grant, Eduardo, et al....

You can use back to back diodes to make a center "dead zone" if you are going from
a negative to a positive voltage.  This won't work well with audio, etc. You could
make the diodes switchable or patchable easily.

I've (not that anyone should care...) never been a big fan of the joystick.  I find
it
hard to control. I have one on my Korg DW8000.  I like the minimoog mod wheel
style better. I really HATE the spring loaded quasi-joystick lever used by certain
Roland synths.  OTOH opinions are like @ssholes everybody's got one.

Good luck !

H^) harry

Grant Richter wrote:

> Hi Eduardo,
> >
> > I ordered 4 of these joysticks along with the stick knob/handle from
> > meci.com, along with a few toggle switches.  nice price too!!
> >
> > I was thinking of making a couple into a sort of "modular" joystick,
> >
> It could almost tempt you into making a product....(sigh)
> Too bad labor is 10x the cost of parts.
>
> > say, a jack for each pin of the pots (totalling 6) with the extreme pins
> > switched to pos. and neg. voltage, maybe with an attenuator pot or a switch
> > for each pin to limit the voltage range.
> > I was thinking of this incase I would want to use the joystick in part as an
> > attenuator,  patching ground to one pin, signal to the other and then output.
> > I thought it mught be interesting to do this on one axis and have voltage on
> > the other.
>
> This is like a "coefficient potentiometer" from an analogue computer. The
> original computers used a 1K potentiometer for low impedance. Not surprising
> then that synth modules use a 1K output impedance.
>
> Coefficients are usually referred to ground. So you only need two jacks per
> pot. The third terminal will almost always be ground. 150K is too high an
> impedance, you will need to buffer it with a voltage follower. A simple
> design is at:
>
> http://www.musicsynthesizer.com/Joystick/1209.htm
>
> which used the MECI joysticks. Plan on putting the trigger buttons nearby. A
> better design is to use an op-amp in the voltage follower configuration (but
> requires +/- supply).
>
> If you insert a switched jack between Vdd and the top terminal, you can
> input a control signal, then attenuate and buffer it. Handy for oscillator
> modulation with simultaneous modulation frequency and depth control.
>
> Making +/- voltage joysticks is difficult without a center detent. Zero is a
> very important number in math since 0 x anything = 0. Using +/- joystick
> makes it hard to shut modulation "off". The Wiard designs always use 0 at
> the bottom/left for a definite off position - your mileage may vary,
> avant-garde musician don't like turn-offs (snort, chuckle, cough, wheeze)
>
> #4 x 3/8" flat head sheet metal screws will thread into the plastic body and
> mount the joystick to the panel. Recessed screw heads are recommended to
> prevent cutting your fingers on the screw heads during very passionate
> performance.
>
> "Each generations illusion of 'newness' is the oldest fossil of all".
> - Jeff Chase

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