Encoders

[Astromaniac]

Hi All,

:help:I'm building a 16" truss dob, almost finished, and own a used ArgoNavis which came with low resolution encoders. Any idea where to find 32k optical encoders? I've been searching the web but no luck.:shrug: Your help is appreciated.:thanx:

Cheers,

John

[glend]

Go back to ArgoNavis and ask. Perhaps they have newer encoders now.

[gary]

Hi John,

For quite a while now, all Argo Navis/Obsession telescope combinations
have been shipping with 32K encoders and some Argo Navis/ServoCAT
combinations with 40K encoders.

To purchase a standalone pair, recommend you contact Gary Myers
at StellarCAT rxdesign@ssvecnet.com or Dave Kriege at Obsession at
telescopes@netwurx.net or purchase a pair from U.S. Digital
https://www.usdigital.com/

Whilst building the scope, any extra effort you put into the following
will pay off in pointing dividends :-

* Making sure the axes are orthogonal. Az to alt should be at right angles
and alt to optical axes should be at right angles.

* Ensuring the altitude bearings and trunnions are circular.

* Ensuring that the altitude encoder is positioned at the
exact alt axis and is mounted "true".

* Ensuring there is a minimum of flex in the trusses.

# Ensuring there are no sources of significant random errors, such
as mirror shift or flex in the focuser when you change eyepieces.

These sources of errors, and others, tend to dominate the pointing
error residuals on most truss Dobs more so than the benefit in going
from say, 10K encoders to 32K encoders.

Argo Navis also has the in-built Telescope Pointing Analysis System
(TPAS) that can analyse and potentially compensate for several of the
more common sources of systematic error. What's more, you can save
a model for re-use on a subsequent observing session.

Be sure to join the Argo Navis User's Group if you have not done so
already for additional tips.
https://groups.yahoo.com/neo/groups/argo_navis_dtc/info

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[Astromaniac]

G'Day Gary,

Thanks for your detailed reply. Much appreciated. I will follow up all of your points to the best of my abilities. The scope is almost , very almost, finished.:) The ArgoNavis I have come with two encoders which I'm not sure about. They only have a number on them: one 8192 and the other 4096. The latter has a small footprint. So what is their true resolution? I've read somewhere that you multiply that number by four to get the true resolution. Is it true? Anyhow I will follow up with the links you gave me and go from there. I've joined the ArgoNavis forum already and I'm learning a lot.
Thanks again, cheers,
John

[AstroJunk]

Whilst technology has marched on since my telescope was built with humble 8k encoders, don't be in too big a hurry to a hurry to splash out in higher resolution encoders if you don't need to.

Heed Gary's advice and you will be able (like me) to be dead centre with a slew/push-to every time :thumbsup:

[gary]

Hi John,

Great to hear the scope is almost finished and we are looking forward to
hearing of your first light report.

The encoder marked 8192 will be 8192 steps and the encoder marked
4096 will be 4096 steps.

So one would enter 8192 and 4096 into the Argo Navis setup menus for
SETUP ALT STEPS and SETUP AZ STEPS depending on which axis
the encoders were mounted.

Since they were marked with the actual encoder steps they were most
likely originally supplied by JMI, possibly some time before 2005.
The 4096 step was most likely on a mount where it was geared 2:1
to provide 8192 steps effective. Perhaps a fork mounted Schmidt-Cassegrain.

The actual part numbers of the encoders are of the form S2-2500-250-IE-D-D
where S2 denotes the package style, 2500 denotes the counts per
revelation which you multiply to get the actual step count and 250 denotes
a 0.25" diameter shaft. So in this example, a 10,000 step encoder in
a 2.2" diameter body package and a 1/4" diameter shaft.

If you have not done so already, you might want to check which version
of the firmware is loaded. Dial up MODE STATUS, STATUS VERSION.

We provide a free license to the latest firmware version 3.0.1.
Get a Registration Code from here :-
http://www.wildcard-innovations.com.au/register.html
User the Registration Code to download from here :-
http://www.wildcard-innovations.com.au/firmware_download.html

If you need help, simply email or phone.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[Astromaniac]

G'Day AstroJunk,
Please meet Astromaniac.:lol: Thanks for your input. I'll decidedly follow Gary's advice, after all is the guru and I'm a complete novice with the AN.:P
Cheers,
John

[Astromaniac]

G'Day Gary,

Thanks again for you help. It has clarified a lot of points which were nagging me. And finally I now understand how to read encoders. That was a big obstacle until now which you've have made simple to understand.
The AN I got came with the latest software update, 3.0.1 and a couple of gears which until now I didn't know what they were for.:) I will register my AN as you've suggested and will post a first light report when the scope is finished.
Cheers,
John

[Astromaniac]

Hi, I've attached some pictures of my almost finished 16" Dob. Other priorities have taken precedence over the construction of it.:sadeyes: It needs only minor adjustments and I haven't tried the ArgoNavis yet. I'll report on its performance when I have a chance to test it fully.

Cheers,
John

[bojan]

John,
Since this post is DIY area... have you seen David Ek's encoder interface (http://eksfiles.net/digital-setting-circles/) web pages?
Or Mel Bartel's webpage (http://www.bbastrodesigns.com/StepperSystem.html)? It uses mouse driver for interfacing encoders.
With mouse interface, or with Ek's setting circles this system can do much more than Argo Navis (GoTo included)... not to mention it is way cheaper.

Also, have a look at OnStep (http://www.stellarjourney.com/index.php?r=site/equipment_onstep) or SoundSteper (http://soundstepper.sourceforge.net/) webpages. AstroEQ (https://www.astroeq.co.uk/tutorials.php) is also very interesting design.

I have used all of the above, except AstrEQ... because OnStep is good enough for me - it can run on it's own (no PC needed.. so not much stuff to carry around). However it has ST4 interface, and it understands LX200 protocol. No encoders yet.

[Baza]

Nice job on the 16. looking forward to the report.

[Astromaniac]

G'Day Bojan,
I've used the Mel Bartel system (which I like it a lot) years ago on an 8" dob which I've recently given it away to a friend, but still got a box and a controller. And I've briefly fiddled with OnStep and SoundStepper a year or so ago. But I didn't go anywhere with them.
I inherited a David Ek's controller, which I had forgotten I had until you mentioned it, from a friend ( who sadly passed on a year ago) and did some static test and sort of liked it but I didn't go any further. I got the ArgoNavis from another friend basically for a song. I have seen it in action several times and liked the simplicity of use but I don't have any real experience of it. What's your experience with the David Ek's controller? I will do some testing with it and compere it with the ArgoNavis. So many choices, so much fun!:)

[bojan]

I used to use Ek's box with Bartels on my 10" Dob, it performed without problems (unlike mouse interface, which has a hidden bug, manifesting itself as overshoot after GoTo or disturbance of the telescope.. probably because of "lost" interrupt from mouse.com).
Ek's box has it's own account of the position, so the above is not the problem.
My encoder was actually a wheel and sensors taken from optical mouse (very rare animals these days), so it cost me next to nothing (apart from some tinkering) to build it and the accuracy was adequate.
I planned to use Ek's box on my future permanently mounted EQ6, sensors will be placed inside the EQ6 housing (some parts will be 3D-printed, some are already made on lathe)... however this most likely depends on OnStep development.

[Astromaniac]

The good old "lost interrupt and the mouse" days. I do remember those days.:)
I got the box with Ek's box (?!) out, there are actually two boxes . One has got Ver. 2 on the pic chip and the other Ver. 3, interesting. And also I found another box with all the bits and pieces for an OnStep system, steppers , controllers etc. For the time being I will use the Argo Navis while putting the other controllers together. The Ek's box is easy as I just have to plug it in. The OnStep needs more attention as I don't remember much about it as I only bought the bits and probably tested the steppers. Help from experts is always welcome.;)
Cheers,
John