DIY Equatorial Telescope Mount

[The Artful Bodger]

You use your telescope to watch Hollywood stars? Is that making like peeping Tom or just too tight to pay to actually get in to the drive in?

[macona]

Nope, Hollywood is in California.

[The Artful Bodger]

I believe we have more stars down here!

[macona]

Eh what? That surely is moving the wrong direction!!!!!!

(According to my view!)

I cant help it if you live on the bottom of the planet.

[The Artful Bodger]

Eh what? That surely is moving the wrong direction!!!!!!

(According to my view!)

[macona]

Good grief, its been over two years now, finally getting back around to working on it.

The filtering was a flop, big time. Just wouldn't work.

So I went with plan B. I am using the SiTech drive to drive a couple little escap 12v ball bearing motors that are directly coupled to 2500 line encoders. Between the encoder and the controller I have a 26LS31 quad line driver tapping into the encoder signals. This sends differential encoder signals to the mitsubishi drives which I put in encoder follow mode.

Made up the final board from perf board this morning and it works, even moves in the right directions without me having to change stuff. Got most of the parameters figured out too. I also need to package up the controller in some sort of case with the motor-encoders.

[macona]

I used LTSpice last night to do some circuit simulation. I hooked up the SiTech controller to the scope and found it uses a 23.45khz base frequency. Popping this info into LTSpice allowed me to come up with a pretty simple 2 pole low pass filter that should give me reasonable ripple and good step response with a 10v max output.

LTSpice filter by macona, on Flickr

[Euph0ny]

First thing I am going to try is making a 2nd order filter to attach to the motor outputs of the controller to smooth out the PWM and then scale it to the +/-10v analog input the servo drives have. Then the encoder feedback from the drives will connect to the encoder inputs on the SiTech. If that does not work I will use the SiTech to drive a couple small dc servo motors to and then use another encoder to drive the Mitsubishi servo drives through their pulse inputs, they can be configured to take quadrature signal inputs as well as CW/CCW and step/dir modes.

I understood not a word of that, but your new part sure is shiny... Well wear!

[macona]

I have finally started working on this mount again. I got an old Quick-Set Hercules 5302 tripod from a friend. It is rated for 150lbs but I am betting it will hold a bit more.

I took another piece of the scrap 17-4 stainless and machine a spud that adapts the 1/2-13 threaded hole in the center of the mount to the 1-1/4" spud on the tripod column. A set screw in the spud locks in a steel socket in the column.

A couple of days ago my Sidereal Technologies Servo 1 controller showed up. First thing I am going to try is making a 2nd order filter to attach to the motor outputs of the controller to smooth out the PWM and then scale it to the +/-10v analog input the servo drives have. Then the encoder feedback from the drives will connect to the encoder inputs on the SiTech. If that does not work I will use the SiTech to drive a couple small dc servo motors to and then use another encoder to drive the Mitsubishi servo drives through their pulse inputs, they can be configured to take quadrature signal inputs as well as CW/CCW and step/dir modes.

Tripod Mount Adaptor by macona, on Flickr

Mount on tripod by macona, on Flickr

[macona]

One thing about a lot of japanese stuff is they really like to use more of the odd-ball connector. In the case of this it uses 20 pin MDR connects for all of the IO for the drive. So I ordered some of those off ebay and ordered some mating connectors for the servo motors from mouser. Or so I thought. In the manual it shows the part number for Molex MiniFit Jr connectors but they are really AMP Mate-n-lok connectors. They look the same but they keying is different and they use different pins. So I ordered the right ones and was able to get the servo cables made up.

For the box to hold all the drive electronics and controller I used an old box from a communications package for a ScanEagle drone. Nice aluminum case with connectors already on the side. I got the wiring finished tonight, now I need tie it all together and see if it works.

Telescope controls by macona, on Flickr

[Paul Alciatore]

Still looking great.

Still waiting to see photos of far off galaxies.

[macona]

Yep, I still need to find a couple more modules for my gamma spectrometer.

The OTA popped off the forks very easily, I did it in about 10 minutes last night. I went down to the hardware store and picked up the bolts for the saddle today and put it together. Some pics of it assembled.

At this point I would say it is mechanically finished. Now I need to put together the controls.

A bit overkill for a 10", I think. It weighs in at 96lbs without the scope. It has gone from portable to luggable.

IMG_8911 by macona, on Flickr

IMG_8913 by macona, on Flickr

IMG_8910 by macona, on Flickr

[Optics Curmudgeon]

Your work is as always superb, like the electronic bottle rack on your desk!
Mark,

See, people are still finding uses for NIM bins.

[macona]

Real handy place to keep water for the iron sponge!

[boslab]

Your work is as always superb, like the electronic bottle rack on your desk!
Mark,