Autoguider November 2015

UPDATE (February 2016): I have recently built an Arduino-based stepper motor controller. For inquiries, kindly leave a comment below or send an email to eteny@nightskyinfocus.com

This stepper motor controller is an improvement of my previous tracker designs. The operation of the micro-controller is explained below:

1. Autoguider port – an RS232 port connects a controller to a computer’s parallel port for receiving guiding signals
2. Power supply – an internal auto-voltage regulator allows the controller to draw power from any 6 to 12 V power source
3. Autoguider RA+/RA- calibration – adjusts the pulses per second of RA plus and RA minus during guiding
4. Stepper Motor Port – an RS232 port connects the controller to the mount’s stepper motor
5. Audio feedback – tracking rate (pulses per second) can be analyzed through an audio port by connecting it to an oscilloscope (or through the computer’s sound card if a computer is used to emulate an oscilloscope)
6. Power on/off – turns on and off the device
7. Step rate indicator – provides a visual feedback of the current step rate
8. Step indicator – indicates which of the 4 coils of the stepper is energized
9. RA plus button – momentarily increases step rate to a predefined value, nudging the telescope to the west
10. RA plus indicator – lights up to indicate that the step rate is momentarily increased
11. RA minus button – momentarily decreases step rate to a predefined value, nudging the telescope to the east
12. RA minus indicator – lights up to indicate that the step rate is momentarily decreased
13. Mode – selects operation between Automatic and Manual mode
14. Manual override – when Manual mode is selected, step rate can be manually adjusted from 1 – 100 hertz (beats per second)
15. Speed selector – when Automatic mode is selected, step rate can be set from any of the 9 pre-defined step rates; for this controller, 1 is assigned to sidereal, 2 for solar, and 4 for lunar step rate, respectively
16. Sidereal calibration – adjusts tracking rate to accurately track stars, galaxies, and nebulas
17. Solar calibration – adjusts tracking rate to accurately track the Sun
18. Lunar calibration– adjusts the tracking rate to accurately track the moon

Related articles:
DIY Autoguider (Part 1: Introduction)
DIY Autoguider (Part 2: Setting-up the Guiding Software)
DIY Autoguider (Part 3: Wiring Diagrams)
DIY Autoguider (Part 4: Autoguiding and Polar Alignment)

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For DIY astronomy projects useful for astrophotography, click here.
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© Anthony Urbano (Manila, Philippines)

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