 |
Two
arm barn door mount based upon design info in Sky & Telescope Vol
75 (Feb 88), page 213 and Vol 77 (Apr 89) page 436.
The two arm model gives slightly better tracking than a single arm model The drive uses a stepper motor to turn the driving screw. I've used a surplus universal joint to connect the motor to the drive screw. |
 |
This
is the underside of the mount. The stepper motor was bought at a
surplus yard for $2.00 and the control circuit was made using the information
from Sky & Telescope Vol 75 (Jan 88) page 80 and Vol 77 (May 89) page
554.
The electronics use an IC 555 as the oscillator and counting IC's to drive the stepper motor coil through the power transistors. The system runs on 12 volt DV. I've included two switches. One reverses the direction of the motor rotation and the second provides a x100 rotation rate so the platform can be quickly reset to it's starting position. |
 |
Link to Jeff DeTray's "Astronomy Boy" page of Astro Photos taken with Barn Door Camera |
|
|
 |