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INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

DIY focuser w/o Motor HAT or PiFace?

2 years 10 months ago
m.baldassarre.85
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DIY focuser w/o Motor HAT or PiFace? #19190
It's not a 28BYJ-48 (unipolar), but a Nema 17 (bipolar). I don't think the a4988 can drive unipolar motors, so I purchased this one for testing. The motor does not vibrate nor gets warm. Looks like no current is flowing at all. Maybe Vref is too low. The voltage on the motor pins on the driver board rises to 4.6 V while I'm sending commands. Starting to think it's a matter of current.

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2 years 10 months ago
HelgeMK
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DIY focuser w/o Motor HAT or PiFace? #19191
Are you sure it is a 5v stepper, and not 12v?

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2 years 10 months ago
m.baldassarre.85
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DIY focuser w/o Motor HAT or PiFace? #19192
On the Amazon page it says "nominal voltage: 3.45 V, nominal current: 1.5A (monophase)".

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2 years 10 months ago
HelgeMK
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DIY focuser w/o Motor HAT or PiFace? #19193
Ok. But 1.5A exceeds the 1A the a4988 is designed for. In any case you would need to check the Vref pin - but pls check the pololu Instructions first...

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2 years 10 months ago
HelgeMK
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DIY focuser w/o Motor HAT or PiFace? #19194

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2 years 10 months ago
HelgeMK
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DIY focuser w/o Motor HAT or PiFace? #19195
Forgot to mention, there are loads of instructions on YouTube on how to convert the 28byj48 into a bipolar stepper - it is actually fairly easy to do.

Best, Helge

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2 years 10 months ago
m.baldassarre.85
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DIY focuser w/o Motor HAT or PiFace? #19196
I DID IT!!!! I took the risk and increased the voltage to 12 V, and not it works! I have no idea why it says 3.45V on Amazon, must be a typo!!

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2 years 10 months ago
HelgeMK
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DIY focuser w/o Motor HAT or PiFace? #19197
Fantastic, well done! - then current will presumably be lower than the 1.5A. Can you check what current is drawn?

I was also running a 5v stepper at 12v. Unless it is getting warm, should be ok - but I am not an electrician (=disclaimer).

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2 years 10 months ago
Kaczorek
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DIY focuser w/o Motor HAT or PiFace? #19198
That's what I thought after I saw your pictures ;-)
I'm glad you got it working!

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Radek Kaczorek
Astroberry Server | NEQ6 | Atik 460EX | Atik EFW2 | ASI 120MM

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2 years 10 months ago
m.baldassarre.85
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DIY focuser w/o Motor HAT or PiFace? #19250
Is there a way to have INDI calculate the necessary number of steps for backlash compensation? Or should I determine it by hand?

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2 years 10 months ago
Kaczorek
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DIY focuser w/o Motor HAT or PiFace? #19252
The driver does not calculate backlash value. You need to determine it manually

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Radek Kaczorek
Astroberry Server | NEQ6 | Atik 460EX | Atik EFW2 | ASI 120MM

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2 years 10 months ago
m.baldassarre.85
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DIY focuser w/o Motor HAT or PiFace? #19301
Any tips on what would be the best way to determine the number of backlash steps?

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