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My DIY equipment: power box and focuser

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#1 MrNomNom

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Posted 15 September 2020 - 01:21 PM

Hi all,

 

First time poster, just want to share my DIY equipment. 

My first project: Power box, basically 12V splitter without much smart features. It has 4 12V outputs. Each output has 5A fuse, so it is "sort of" safe if something dodgy happens. Additionally it has 2 USB ports. These both have 5V 3A output. Since it will be mainly used for RaspberryPi running astroberry 3A will be more than enough. Also it has custom 3D printed enclosure.

Some images:

IMG 6905
IMG 8253
IMG 6879
IMG 6876


Second project: Automatic Focuser. I am using stepper motor (Nema 17 size), motor driver is A4988 and made custom board for it (basically it is Arduino nano but on a custom board). Software I am using is made from combining couple open source projects from internet (some stuff taken from myFocuserPro2, some stuff from ardufocus). Also it has audio jack port connected to one of microcontrollers pins. I am planing to use it for remote controller and/or temperature sensor.
Since it uses Moonlite protocol I dont need custom driver for IndiLib, so I can use already installed drivers smile.gif

Ps. I designed custom enclosure which doesnt use any brackets, I am bit proud of that too laugh.gif (yeah, I know, it look similar to Sesto Senso2 smile.gif

Some images:

IMG 1191
IMG 9037
IMG 5656

 

here is short video of how it works: https://i.imgur.com/ECkVGjF.mp4

 

Any suggestions, comments and questions are welcome!


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#2 rkinnett

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Posted 15 September 2020 - 04:12 PM

That's awesome!  Well done, and welcome to CN.  Happy to have another maker in the forum smile.gif

 

Just curious, which NEMA17 motor are you using?  Here's a survey I compiled of various steppers and suitability for focusers, showing some lighter, cheaper options with closer matches to required torque and step size.  I'm using a GM20BY-12V-125 and a Moons PG22L in my focusers (driven by A4988 with ESP8266 running myFocuserPro firmware).  Looks like you're already committed to a NEMA17 but maybe this could be useful for future projects.

 

That power distribution box looks great.  Thanks for sharing.

 

Cheers!


Edited by rkinnett, 15 September 2020 - 04:15 PM.


#3 Jinux

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Posted 15 September 2020 - 04:41 PM

It looks great!

Wouldn't it be better to use switching regulator on 5V outputs?  Max 6A on 7805 (I guess?) would waste (12-5)V*6A = 42W under full load. 

 

I made power weight using wood-3Dprinted housing-Ryobi 18V batteries.

Center hole is for Losmandy 1.25" and it provides 16lbs weight with 360Wh power when all 6 batteries plugged in, which can support 24Ah usage with 80% efficiency of switching regulator down to 12V equipment.

Attached Thumbnails

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Edited by Jinux, 15 September 2020 - 04:45 PM.

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#4 MrNomNom

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Posted 15 September 2020 - 11:44 PM

That's awesome!  Well done, and welcome to CN.  Happy to have another maker in the forum smile.gif

 

Just curious, which NEMA17 motor are you using?  Here's a survey I compiled of various steppers and suitability for focusers, showing some lighter, cheaper options with closer matches to required torque and step size.  I'm using a GM20BY-12V-125 and a Moons PG22L in my focusers (driven by A4988 with ESP8266 running myFocuserPro firmware).  Looks like you're already committed to a NEMA17 but maybe this could be useful for future projects.

 

That power distribution box looks great.  Thanks for sharing.

 

Cheers!

Hey, thanks for a link, I will investigate it bit later.  As for my motor I am using this one "42hm34-1334". 



#5 MrNomNom

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Posted 15 September 2020 - 11:48 PM

It looks great!

Wouldn't it be better to use switching regulator on 5V outputs?  Max 6A on 7805 (I guess?) would waste (12-5)V*6A = 42W under full load. 

 

I made power weight using wood-3Dprinted housing-Ryobi 18V batteries.

Center hole is for Losmandy 1.25" and it provides 16lbs weight with 360Wh power when all 6 batteries plugged in, which can support 24Ah usage with 80% efficiency of switching regulator down to 12V equipment.

Hey, thanks for comment. Its only max 3A, so my waste is around 21W. But I have considered this, my idea was to create PCB as simple as possible for my Version 1 :) I am actually designing PCB with several separate switching regulators right now, but progress is bit slow bth. 

 



#6 CinciJeff

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Posted 16 September 2020 - 11:04 AM

Nice work! Those boards look great - do you have a supplier that will make one-off boards for a reasonable cost?

 

 

 

Jinux: I made power weight using wood-3Dprinted housing-Ryobi 18V batteries.

A "power weight" is a great idea! Very clever!



#7 TelescopeGreg

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Posted 16 September 2020 - 01:05 PM

Wouldn't the weight of the batteries drop as the electrons are drained?  Another C&W song title:  "East Heavy and Morning Light"

 

{ahem}... 

 

Nice work.  We grumble about how much all our gear weighs, but nobody really does anything about it.  Very inspiring.



#8 rkinnett

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Posted 16 September 2020 - 03:31 PM

Hey, thanks for a link, I will investigate it bit later.  As for my motor I am using this one "42hm34-1334". 

Depending on your scope and focuser geometry, that 0.9 deg/step may or may not get you good enough step resolution for autofocusing to work reliably.  You might need to micro-step.  The myFocuserPro2 guidelines suggest you need about 20 steps in your focuser's "critical focuser zone".  You'll get about 5 steps in the CFZ if you full-step which might be good enough, despite the guidance.  I don't know how sensitive autofocusing is to this.  See if it works reliably using full steps, compared to by-hand FWHM optimization, and try micro-stepping.  Sorry if you're already aware of all of this and are already planning to do this or similar comparison.



#9 Jinux

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Posted 16 September 2020 - 03:49 PM

Wouldn't the weight of the batteries drop as the electrons are drained?  Another C&W song title:  "East Heavy and Morning Light"

 

{ahem}... 

 

Nice work.  We grumble about how much all our gear weighs, but nobody really does anything about it.  Very inspiring.

Hm... Wait a sec. Electron loss and the weight of photons accumulated on camera sensor will work together east heavy before meridian flip while opposite after flip. Darn. It's dilemma.



#10 megachriops95

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Posted 16 September 2020 - 08:51 PM

How fine steps can the motor do?

 

Is there any reduction built in?



#11 MrNomNom

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Posted 17 September 2020 - 01:10 AM

How fine steps can the motor do?

 

Is there any reduction built in?

I have played with microstepping, so far I am sticking to 1/2 steps. Motor driver can do 1/16 I think.

Ps. motor itself doesnt have reduction


Edited by MrNomNom, 17 September 2020 - 01:12 AM.


#12 MrNomNom

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Posted 17 September 2020 - 01:12 AM

Depending on your scope and focuser geometry, that 0.9 deg/step may or may not get you good enough step resolution for autofocusing to work reliably.  You might need to micro-step.  The myFocuserPro2 guidelines suggest you need about 20 steps in your focuser's "critical focuser zone".  You'll get about 5 steps in the CFZ if you full-step which might be good enough, despite the guidance.  I don't know how sensitive autofocusing is to this.  See if it works reliably using full steps, compared to by-hand FWHM optimization, and try micro-stepping.  Sorry if you're already aware of all of this and are already planning to do this or similar comparison.

I know, I am doing microstepping. Motor driver supports up to 1/16 microstepping. 


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#13 MrNomNom

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Posted 17 September 2020 - 01:13 AM

Nice work! Those boards look great - do you have a supplier that will make one-off boards for a reasonable cost?

 

 

A "power weight" is a great idea! Very clever!

I have ordered these boards from jlcpcb




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