Hi Everyone. I am just getting back into astrophotography, and with my newly acquired skills, have finally been able to design a 1 Rpm Barn door tracker system, with a stepper Motor. All the electronics are done, just have to do the wood part.
If anyone is interested, let me know, and I'll make some more, i.e.
The circuit board, Stepper motor, 2 gears and the curved rod.
It just requires 4 * 1.5 volt batteries for it to run.
No programing required.
Just select CCW or CW and switch ON.
Not Sure I know how I will mount the stepper to the wooden board.
I was thinking of maybe going back to one of my older designs where the stepper is mounted to the circuit board, then hollow out the wooden board and screw on the circuit board to the wood.
Hey Screech,
as promised, attached are the photos I have from my barn door. Plus a stack of about 30 images at 3minutes 400ISO taken off my barn door.
First image is a manual (hand turned) version. That got very tedious after about 1 hour. Second image is the first motorised version, which because of the way the worm gear was drilled out, it vibrated a fair bit. The third and fourth images were my successful version, as you can see, cobbled together out of Lego gears. But hey, it worked.
Back then (June 2013), polar alignment was still a mystery being discovered, so I could get images no longer than 4 minutes at 55mm
That's pretty neat.
any details on the mcu used, is it a picaxe or is it just a 555, and the pulse frequency? what is the overall reduction.
Cheers
Alistair
Yes it's a Picaxe microcontroller.
32 whole steps stepper motor with built-in 64:1 reduction gearbox.
=================================== ======
Coil "A" is energized for around ~13 milliseconds, then coil "B" for ~13milliseconds, then coil "c" for ~13milliseconds, then coil "D" for ~13 milliseconds, then repeat. Always repeat.
1 RPM rotation accuracy error = perfect at room temperature.
1 RPM accuracy error = -0.1second per hour at 4 degrees Celsius.
Tested electronically to a 100th of a second for 1 hour.
Hey Screech,
as promised, attached are the photos I have from my barn door. Plus a stack of about 30 images at 3minutes 400ISO taken off my barn door.
First image is a manual (hand turned) version. That got very tedious after about 1 hour. Second image is the first motorised version, which because of the way the worm gear was drilled out, it vibrated a fair bit. The third and fourth images were my successful version, as you can see, cobbled together out of Lego gears. But hey, it worked.
Back then (June 2013), polar alignment was still a mystery being discovered, so I could get images no longer than 4 minutes at 55mm
Thanks Scotty.
That's a solid looking Barndoor and mount.
I use to remember turning things by hand too. It's was no fun. I'm glad you worked out how to do it with a motor.
32 whole steps stepper motor with built-in 64:1 reduction gearbox.
=================================== ======
Coil "A" is energized for around ~13 milliseconds, then coil "B" for ~13milliseconds, then coil "c" for ~13milliseconds, then coil "D" for ~13 milliseconds, then repeat. Always repeat.
1 RPM rotation accuracy error = perfect at room temperature.
1 RPM accuracy error = -0.1second per hour at 4 degrees Celsius.
Tested electronically to a 100th of a second for 1 hour.
That's excellent. For 3 or 4 minute exposures, next to nothing. Pausing the mount for 10 seconds between images can improve the quality of the final stacked image, as well, providing you keep the target in the view finder.
. All the electronics are done, just have to do the wood part.
