3 replies to this topic

[TTang]

Hi all,

 

About half a year ago, I bought a 1999 Celestron NexStar 5 at a yard sale for $50. It was my very first time getting into telescopes and astronomy in general. So I really don't have much experience, forgive me if've done something dumb

 

I'm currently working on refurbishing it by replacing its original control electronics with a modern ESP32-based system, and I wanted to share my progress and ask for advice on next steps. I’ve learned a lot through this process and would love your feedback or suggestions—especially from those who've done similar projects.

 

What I’ve done so far:

 

Replaced the original hand controller and board with an ESP32.

 

Implemented basic joystick-based motor control through a web interface (HTML + WebSocket).

 

Investigated the original L293DNE drivers and confirmed that one channel was used per motor (possibly for better current handling)

 

Confirmed successful motor direction and PWM speed control via ledcWrite() on the ESP32.

 

Read and record the data from the encoder of its original motor through PCNT on ESP32.

 

What I plan to do:

 

Develop a more advanced slewing and tracking system.

(So it can follow the stars automatically without manual controlling)

 

Incorporate absolute orientation sensors (e.g., accelerometer + magnetometer).

 

Add a GPS module for location reference.

 

Possibly develop an external wireless remote with a physical joystick (NRF24L01 or Bluetooth).

 

Design a custom PCB mainboard to integrate all components.

 

Replace the OTA mounting with a dovetail saddle or tube rings, preferably without drilling.

 

Add support to planetarium softwares(like Stellarium).

 

Replace L293DNEs with TB6612FNG (Higher current&efficiency and lower heat generation)

 

Some questions:

 

Has anyone used pipe hangers or PVC rings to mount a NexStar 5 OTA as a tube ring substitute? How well do they hold up in practice?

 

Would a 150mm pipe hanger with rubber lining fit the NexStar 5 OTA securely?

(like this one)

 

Are there any gotchas when working with this particular vintage NexStar gearboxes or motors?

 

Do you think a sensor based absolute positioning system (Accel + Mag) is feasible for Alt-Az alignment?

 

Any other recommended modules or features for DIY GoTo control you'd suggest?

 

I'm still new to the world of telescope control systems and astronomy hardware, so any suggestions, warnings, or examples would be really helpful. I'm especially looking for insight into integrating angle feedback and star alignment logic with the ESP32.

Would love to hear how others modernized their older scopes too!

 

Thanks in advance!

 

 

Some pics:

 

My testing boardyYeah, it's a mess)

 

Video:

https://m.youtube.co...4?feature=share

Attached Thumbnails

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[RichA]

You might want to get a real set of rings for $40-$50.  

[TTang]

You might want to get a real set of rings for $40-$50.  

 

Thanks for replying ! I’ve looked around, but I couldn’t find tube rings around 146mm diameter in the $40–$50 range—they usually go for over $100. (or would you mind providing a link? Thank you.)

 

But I did find some guiding scope rings with three adjustable screws for about $50. My concern is that those rings are usually designed for much lighter guide scopes. Unlike split rings or full tube rings, all the load would be concentrated on just three (or six if using two of them) contact points.

 

Do you think that would be strong enough to securely hold a 5" Schmidt-Cassegrain? Also, I’m a bit worried they might scratch the OTA..

[mclewis1]

I'd say your inexpensive ring setup could work. Roughly 150mm inside diameter (plus with lots of ability to open them up) with a 146mm tube is not a problem. Most folks will use a little adhesive backed felt strips to fill in the differences. The felt also allows the tube to rotate a bit (depending on the pressure exerted on it). The pipe hangers you've linked to however are very lightweight and there is likely to be some flex involved. I think this could work for a lighter weight tube like the C5 for visual work, it's certainly worth a try at those prices.