turns easily through the Delrin
nut, and that both pieces of
Delrin rotate easily in their
UHMW polyethylene mounts.
Any binding may cause the
stepper motor to bind.
While it is possible to drive
the stepper motor with an
integrated circuit for that
purpose, I choose to drive it
directly with MOSFET transistors
controlled from an Arduino
board. The program will deal
with the necessary signals to
switch the MOSFET transistors on
and off. The Arduino board and
its associated shield are mounted
on the base of the barn door tracker.
The Arduino board and additional
circuitry can be powered with a
7. 2 volt NiCd battery for portability or
a standard plug-in power supply.
The schematic of the stepper
motor driver is shown in Figure 7. The
circuit consists of an Arduino board
with four of its outputs driving
MOSFETs that control the current
28 January 2015
■ FIGURE 3.
■ FIGURE 4.
■ FIGURE 6. ■ FIGURE 5.