Making an old Meade motorized EQ into a goto, anyone done it? I'm going to modernize this 853.

[Kilohertz]

I am about to pickup a classic old Meade 856 Newt which hasn't been used in years. I'm not sure if the existing motors work or not, it comes with the #47 controller. I would like to modernize this with a goto controller, I have a Sky-Watcher Synscan NEQ-3 on the way as  well and would like to use the hand held control from it. I'm an electronics nut and think I should be able to make this work. 

I'm wondering if anyone here has one of the old Meade EQ mounts, or similar and has modified it? Also, anyone have the manual for the Meade 856/853 or the 826 and 47 controller?  It would help me to know how the original system worked.

Look forward hearing from you.

Cheers

Edited November 17, 2023 by Kilohertz

[Cosmic Geoff]

There have been discussions here about making up GoTo controllers for the Sky-watcher EQ-5 mount (the Sky-watcher Synscan upgrade kit being rather expensive) and kits are available that might be adaptable for the Meade mount. 

All sorts of old mounts have been upgraded to GoTo, and there are one or two companies that specialise in this, but expect a $1000+ bill.

On 17/11/2023 at 01:35, Kilohertz said:

I have a Sky-Watcher Synscan NEQ-3 on the way as  well and would like to use the hand held control from it.

I don't think so, unless you are a real electronics genius. I have never heard of these handsets working with any other system. The builders of DIY EQ-5 kits settle for having it controlled from a laptop.

[Kilohertz]

3 hours ago, Cosmic Geoff said:

 The builders of DIY EQ-5 kits settle for having it controlled from a laptop.

This would also be a completely acceptable solution as I will already have a laptop for image capture, I'll do some more research.

Thanks

[Cornelius Varley]

Not sure if an off the shelf system (Synscan or similar) would work with your mount. 

meade-catalog-reflectors-1978.pdf (astrosurf.com)

[orly_andico]

1) You should be looking at OnStep - all the hard work has been done by Howard and the team, a complete build can be done under $200, maybe even under $100.

2) The Meade 826/856 may not have a full declination worm, only a tangent arm. You'll need to check on this as GoTo range will be severely limited if so, as the DEC would not be able to be driven a full 360 degrees.

[Kilohertz]

Orly, thanks. I have a couple of your pages open already, working my way thru the 600E goto right now.  I started reading the onstep pages, there's a lot to digest but it looks very good. Being an electronics tech, it's right up my ally.

Thanks!

[orly_andico]

OnStep didn't exist when I did that 600E goto conversion.. ended up buying an expensive (over 500 euro) German GoTo controller which is now defunct because the developer stopped working on it.

The huge advantage of OnStep is that it's open source. There are a lot of PCB's floating around but the simplest possible implementation can be an ESP32-based Uno clone with two DRV8825 or TMC2xxx Pololu-style stepper drivers.

BTW I used to have an Ender-3 3D printer with DRV8825 drivers, and I upgraded the motherboard to one using SilentStepStick (TMC2xxx) and it was night and day. Amazing. Stepper motors driven by TMC2xxx are even quieter than servos.

Here's one of the canned/pre-stuffed OnStep boards that I bought from George Cushing on the OnStep forum. I've not actually powered it up..  (the AP600 is off somewhere, and I have two perfectly serviceable GoTo mounts):

So below you see the ESP-32 is the OnStep brains (Arduino replacement), the small board at the top right is the WeMos D1 (ESP8266) which provides the Wifi, the two Pololu-style stepper drivers, there's also a Dallas chip for the RTC on the main board.

I'm not quite sure why the separate WeMos D1 is needed, since the ESP32 itself has WiFi and Bluetooth. I think to avoid over-complicating the code.

 

Edited November 23, 2023 by orly_andico

[Kilohertz]

Orly,

Very cool, I love it. Yes very familiar with Arduino and ESP8266 boards, I have a couple of ESP32 boards that just arrived as well as several leftover motor drivers from previous telecine project. I just found in my shop, 4 brand new German made Berger Lahr  5 phase steppers, NEMA 17 size I think, may be 27, RDM 554/50, 40 volts .2A  .72* full step or .36* half step, you can hardly feel the cogging when you spin the shaft. They need some funky drivers though, I still need to figure that out. 

I'm just getting going with various aspects of AP, things are arriving daily, I'll hopefully be able to start capturing short exposures this weekend on my tripod.

Lots of fun, thanks for your guidance.

Cheers

[Kilohertz]

20 hours ago, orly_andico said:

2) The Meade 826/856 may not have a full declination worm, only a tangent arm. You'll need to check on this as GoTo range will be severely limited if so, as the DEC would not be able to be driven a full 360 degrees.

Crap, just found out it is a tangent arm...a little more research is needed.

thx

[orly_andico]

OnStep will work even with a tangent arm. But you have to push the scope to the "general" area and then it can do a short GoTo using the limited travel on the tangent arm.  It would need to know where it is when you push it there though - which means doing a plate solve and then sync'ing the mount to the plate-solved position.

Also: my personal experience, 5-phase steppers are a complete pain.  You do need some really exotic drivers which are impossible to find inexpensively.

Edited November 24, 2023 by orly_andico

[Kilohertz]

I am going to start researching the replacement of the tangent arm drive with a complete 360* setup. I have an old Bushnell EQ mount that may be a donor. I have a lathe so if needed I can bore the center hole to fit the Meade shaft. 

I'll have some time this winter and hope to get this working, I'll look around to see if I can find others who have updated a tangent arm to 360*.

Cheers