module a-174-4 generates several control voltages and a gate signal controlled by a spring-loaded x/y cross potentiometer (so-called joy stick). the control voltages for x and y are controlled by the x and y
position of the joystick in the usual way. the third control voltage z is controlled by the rotation of the spring-loaded joystick knob. the gate signal is generated by a button at the center/top of the joystick
knob. as an additional feature four control voltages are generated that are assigned to the quadrants of the cartesian coordinate system. these quadrant voltages are derived from the x and y voltages by means of
a special algorithm.
for each joystick function the non-inverted signal (x, y, z) as well as the inverted signal (-x, -y, -z) is available. the generic joystick control voltages are bipolar and range from typ. -5v (lowest position)
via 0v (center position) to typ. +5v (highest position). by means of the offset controls ox, oy and oz a variable voltage of up to 5v can be added to the generic voltages. that way it's possible that the x, y
and z outputs become pure positive (0...+10v instead of -5v...+5v). that's necessary if e.g. vcas have to be controlled, because vcas require a pure positive control voltage. the offset voltages can be adjusted
by means of three small potentiometers. when the control in question is fully ccw no offset is added and the "pure" control voltages x, -x, y, -y, z and -z without offset are generated. as soon as the offset
control in question is moved clockwise up to +5v are added to the voltage in question. the offset voltages are also added to the inverting outputs. with max. offset the range of an inverted output becomes also
pure positive (+10v...0v instead of +5v...-5v). these six voltages are output at the sockets "x+ox", "-x+ox", "y+oy", "-y+oy", "z+oz" and "-z+oz". each of these outputs is equipped with a dual color led
(red/yellow) that displays the present voltage and allows to distinguish between positive (red) and negative (yellow) voltages.
on top of this the four quadrant voltages q1, q2, q3 and q4 are calculated. a quadrant voltage becomes positive when the joystick is positioned in the quadrant in question. the absolute value of the voltage
depends upon the position of the joystick lever in the quadrant. by means of the overlap control overlapping of the voltages between the quadrants is attainable. when the overlap control is fully ccw there is no
overlapping, i.e. only the control voltage of the currently addressed quadrant becomes positive, all others are zero. as overlap is increased the voltages overlap more and more. e.g. both outputs q1 and q2 become
positive in the 12 o'clock position of the lever when the overlap control is turned up. the overlapping increases with the position of the overlap control. we will explain this behaviour by means of a drawing
shortly. each quadrant output is equipped with a single color led that displays the present voltage. the quadrant outputs provide only positive voltages in the range 0...+10v.
notes:
because of the construction height of the joystick (about 7 cm) the module cannot be installed into the cases a-100p6, a-100p9, a-100pms6, a-100pms9 and a-100pms12 during transportation as the depth of the case
cover is not sufficient. into the base cases a-100pb and a-100pmb as well as in all other cases without cover the module can be installed without problems. we are about to find a solution for this problem (maybe
deeper covers, but this requires also the modification of the cartons).
because of the outreach of the lever in the extreme positions (fully left, right or down) it may be necessaey to arrange the adjoining modules in a different way or to install blind panels instead of modules. it
depends upon the controls and sockets of the adjoining modules if that's necessary.
in theory it's possible to remove the return springs for the x and y potentiometers. for this the joystick case has to be opened and the return springs removed by means of suitable tools. but because of the small
friction it cannot be guaranteed that the lever will remain in the last position when it is released. that's why we do not recommend this modification. even the warranty is void if such a modification is carried
out by the customer.
the joystick is a wear and tear part and is excluded from the warranty !
for this module the bus connection is located at the top because of the position of the joystick at the bottom (in contrast to most other a-100 modules with the bus connection at the bottom)!
this module has a maximum current draw of 50ma. it requires 12 hp/te worth of space to fit in a eurorack frame.
