To take a long exposure of the stars you need to comensate for the earths rotation. This is my star tracker.
StarTracker control. When a Nema 17 or equivelent stepper is connected to a compatable controller and the output is geared as shown, then the final output shaft should revolve once per siderial day.
Hardware used:
- Nema 17 stepper with 99.0506:1 planetory gearbox
- final drive 3:1 toothed belt
- TB6600 stepper driver.
- Arduino Uno R3
- 0.91 INCH OLED Display: Resolution is 128*32
- 8 x push buttons
- Siderial day = 86164.1 seconds
- gearbox 99.0506:1
- pully 3:1
200 steps 16 microsteps each microstep = 0.0906145625seconds = 90.6145625ms