Star Tech Journal

STAR*IBCH Journal
April 1988
12
Suzo Joystick Technical Review
James Beck
BAM Engineering
Greater Southern Distributing Co.
Atlanta, Georgia
Being a full time technician, for a distribu-
tor, and an electronics enthusiast in gen-
eral, I have always been amazed at the
tendency of designers to look for the most
complicated solution to a simple problem. I
just love it when I see a device that does its
job well with a minimum of extraneous
"junk." For the past few months I have had
a chance to put such an item through its
paces, the Suzo 4/8-wayinductivejoystick.
The joystick is manufactured in the Nether-
lands by Suzo and is distributed by J-S Sales
Company Inc., Mount Vernon, NY. I was
supplied with two identical joysticks, one
was put into use in the field and the other
was kept in the shop for my own private
abuse, and boy did I abuse it!
that way the joystick circuitry will "see" the
same voltage as the board.
CONSTRUCTION
The overall construction of the stick is what
you might expect of any high quality me-
chanical stick on the market. The knob is
molded to the shaft and tapers as it goes
down. It has a very good feel in the hand.
There is also a molded-on liquid deflector
and darn arrangement that is designed to
keep spills out. The mounting plate has two
sets of bolt holes to match up with most
joysticks now in use. Attached to this plate
are four stand offs that the electronics hous-
ing is attached to, and 8 detent areas to give
a positive feel to the player of where the stick
is at, at any particular time.
I
INSTALLATION
The joystick comes fully assembled with a
single instruction sheet. This instruction
sheet is my only real, if minor, gripe. Like
many imported items, the included instruc-
tions were not translated well into the
American language. (English if you prefer,
but we don't exactly speak "English" any-
more.) The spelling and syntax is a little off.
Even so, the installation process is pretty
self-explanatory. The instructions state that
the supply voltage to the joystick should be
between 4. 75 and 5.25 (the standard range
for TTL), but there is no mention on how to
ensure this. If you were to bring wires up
directly from the power supply, odds are the
voltage to the joystick will be MUCH higher
than 5.25 volts maximum. I would suggest
obtaining the power by tapping into the +5
and ground near the board's edge connector,
THEORY OF OPERATION
I know, so far it sounds like any other
joystick. The knob, shaft, and mounting
plate do look like those on joysticks available
now, but that is where the similarity ends. In
the area normally used to mount blade or
microswitches is where the electronics are
housed. This is where all of the "magic" takes
place. Figure 1 shows a block diagram of the
system used to detect the joystick's position.
The oscillator and the amplifier pulse a high
frequency signal through the drive coil,
which actually circles the shaft of the joys-
tick. The ferrite bead is mounted onto the
end of the joystick shaft. As the ferrite bead f
is moved closer to a particular pickup coil, or
set of coils in the 8 way mode, the magnetic
flux is increased over that coil or coils. This
results in a greater induced voltage. This