Cheap Static Suppresser Solution

Reprinted from Energy Magazine, March 1989

Article by Mike McCarty

Last year, I had a close call.  As I was reaching for the "on" switch on our
C64, I felt a static electric spark jump from my finger to one of the pins in
Control Port 2.  This occurrence frequestly precedes the inability of the
computer to accept input from the keyboard or from the joystick ports.  In my
case, I was fortunate.  With baited breath I turned on the computer.  Since it
functioned normally, I presumed that the spark had jumped to the ground pin. 
I was not willing to repeat the performance and trust that I would be just as
lucky the next time.  As a temporary solution, I plugged the joy-stick into
Port 2 and kept it there.  This helped, but there wer times when I found the
joystick plugged into Control Port 1 leaving the other port open to zapping. 
A better solution was needed.

We recently installed static strips on our PC's at my office.  These work
quite well but also cost about $20,00 each.  For a couple of dollars worth of
materials I was able to construct a reasonable static suppresser that is
physically more suited to mounting on a C64.  For less than a dollar, I bought
a 5inch X 5 inch piece of electrically conducting foam from Radio Shack and
cut a piece to cover both control ports.  After cutting a slit in the lower
half of the piece I put vinyl tape over the inside where it may contact the
pins in the port and stuck it to the case with double-sided adhesive.  To
ground the foam, I pushed on load of a ! megohm resistor into the foam.  On
the other lead I soldered a wire with a terminal which I connected to a screw
in the chassis of the surge suppresser.  It woucld also have been connected to
the screw on the electrical outlet face plate.

So far the results have been passable.  The resistor has a tendency to pull
out of the foam if the wire is pulled, but it isn't too bad for a first
prototype.  The bas layout seems sound.  Even with no joystick plugge in, both
ports are protected by flaps that can be lifted to insert joystick plugs.

If anyone else has tried variations on this design or other solutions, please
suggest improvements or simpler solutions.
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