Fig. E: The rotary encoder mounted to the stripboard,
with the nail axle (circled) glued in. Fig. F: Tape the
stripboard to the inside of the project box with the
axle sticking out of the drilled hole.
project box. I stuck it down with double-sided tape,
then went over it with regular tape (Figure F).
5. Mount the wheel and the board.
Time to rip the wheel from your R/C car. If it comes
with a gear in it, as mine did, try leaving it in to act
as a spacer for your wheel. I simply used super glue
to mount my wheel. If your wheel’s hole is wider
than the rod (Figure H), roll up some paper to pad
out the hole, or gum it up with Blu-Tack poster putty.
Tape the circuit board to the bottom of the project
box and drill a hole in the side of the case for the
cable to escape through (Figure G). Then clip and/or
screw the 2 halves of the box together and test it!
6. Test it.
Plug your new scroll wheel into your computer and
give it a whirl. I use a USB mouse with my PC, so the
PS/2 port was free. If you used a PS/2 mouse like
I did, you’ll have to reboot your PC after plugging it
in for the BIOS to recognize it.
Fire up something scrollable, be it your Winamp
library, your browser, or a massive e-book, and give
it a test. If you find it’s too sensitive or not sensitive
enough, then go into your Control Panel and adjust
your mouse properties, specifically, how many lines
Fig. G: Both boards taped into position. Fig. H: The case
closed, and the wheel mounted.
you scroll with 1 turn of the wheel.
As an added bonus, see if your wheel has enough
momentum to scroll under its own weight with a
flick of the wrist, like mine does.
7. Take it a step further.
I wanted to emulate the PowerMate as much as
possible. A little Googling turned up an awesome
piece of software called Volumouse ( nirsoft.net/
utils/ volumouse.html). It lets you adjust your PC’s
volume by holding a keyboard button and scrolling
up or down. It will also resize windows and change
brightness, all according to the conditions you give it.
See a video of the PowerFake controlling
Volumouse at makezine.com/go/diyscrollwheel.
(Originally published on instructables.com.)
Daniel Walker ( firstname.lastname@example.org) is your average
16-year-old who loves to make stuff, sometimes to save
money, but mostly for fun. A regular on instructables.com,
he loves simple solutions to complex problems.