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Subject: Joystick

From: "jhaible" <jhaible@...>
Date: 2000-04-13

> Never mind my last post. The output would only swing from +10 to 0 volts,
> and bipolar would probably be more useful. See the attached image for a
> quick and easy schematic. The opamp type is not critical.

The Joystick module I've built some years ago for my JH-3 system
has the following features:

CV Output jacks for X and Y, bipolar +/-5V each.
Two bicolor LEDs for X and Y.

Four VCAs with inputs/outputs connected in "diamond shape"
with a variety of functions:

(1) Mixing of 4 inputs into one output with 2 modes (see below):
2-dimensional crossfading.
When only to of the 4 inputs are connected, the other ones are
automatically normalized to the negative (inverted) input signal
of the adjacent inputs. (Acting as a 2-dimensional reversible

(2) Distributing one input to 4 outputs (2-dimensional or "quad"
Use this as "Azimuth coordinator" for a real Quad system, or
connect two of the outputs to the effect send of a true stereo
reverb in an ordinary stereo system.

(3) "Mode" switch, applies to both (1) and (2):
a) normal panning / crossfade: When joystick is in center,
result is a mix of 50% X and 50% Y.
b) center zero: When joystick is in center, there is no output
signal at all. This means independent selection of 4 different
sources, for instance.

I don't remember circuit details, but I think I found a way to do it all
with just a SSM2024 and 2p2t switches - kind of matrix connection.