A DIY isosceles-style barn door star tracker for astrophotography, built from wood and ball bearings and driven by an ESP32-S3 and a NEMA17 stepper motor. It rotates the camera to cancel out Earth's rotation, so long exposures produce sharp stars instead of trails and capture faint detail in nebulae and distant galaxies (see results).
| Tracker |
Electronics |
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Two wooden boards are joined by a hinge aligned with the celestial pole. A stepper motor drives a threaded rod that pushes the boards apart at sidereal rate.
A constant rod speed only approximates the required rotation and builds up a tangent error over time. StarHinge instead calculates the exact rod length for the target hinge angle θ(t) = ω · t from the frame geometry and converts it into motor steps, timed by the ESP32's microsecond hardware timer.
| Untracked |
Tracked with StarHinge |
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| Component |
Details |
| Microcontroller |
ESP32-S3-DevKitC-1 |
| Motor / Driver |
NEMA17, TMC2209 (1/8 microstepping) |
| Drive |
M8 threaded rod, 1.25 mm pitch |
| Frame |
Wood |
| Firmware |
C++, Arduino framework, PlatformIO |
| Power |
2S Li-ion battery pack, step-down converter |
| Bearings |
20mm pillow block bearings for the threaded rod |
| Andromeda Galaxy (M31) |
Pleiades Star Cluster (M45) |
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