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  #21  
Old 23-11-2018, 07:10 AM
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Alex,

I do not give up that easily.. and I have too many surplus motors already from mods I did in the past ;-)
So, lets see what happens, I intend to finish this - it is the personal challenge now :-)
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  #22  
Old 23-11-2018, 07:37 AM
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I like your spirit but please do not let it come before things that are more important for you or more particularly that may be more important as far as your good wife is concerned.
Alex
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  #23  
Old 23-11-2018, 01:28 PM
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Alex, I just checked, your LXD-55 has the same worm gear as my LXD-75..
which means my old controller (when un-modded) should be suitable for your mount (unless motor gearboxes are different), with some re-wiring.

Also, do you need buttons? Do you need DEC drive?
If not, with a little tinkering I can assemble simple electronics (only tracking) for you from parts I have in my drawers.
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  #24  
Old 23-11-2018, 02:11 PM
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ĢHi Bojan
What you have is not anything to do with a Meade unit, although I do have a LXD 55 that has a dud hand box.
I dont know what brand ot is but I guess you could say Celestron because it came with a 150 mm refractor that is a Celestron.
All I need is RA drive as the dec has been removed and replaced with a ply unit to mount the camera and dec adjustment is simply down to moving the camera to the target object and screwing the base mounting screw to hold the camera at the appropriate angle.
As it is for wide field with short exposure so dec tracking is not required.
There is a photo earlier here showing the idea.
So all it has to do is turn at the appropriate speed on RA. Dec is fixed or rather removed (see photo)
I figure with good PA and short exposure the unit should be great for wide field.
The photo above shows a one camera ply mounting unit but I have since made one that holds two cameras...which I cant photograph as it is in Sydney...but it is just a box sortta thing.
I took the dec off to reduce weight and make the unit easy to manage.
I dont need buttons or even an on off switch as the power can be cut off when I take the clips off the battery.
Alex

Last edited by xelasnave; 23-11-2018 at 02:26 PM.
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  #25  
Old 23-11-2018, 02:20 PM
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Here is the photo adjusted to see it clearer.
Alex
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  #26  
Old 23-11-2018, 02:29 PM
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The shiney metalic thing on the ply box is the mount for yhe Polemaster camera...the blobs are blue tack☺
Alex
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  #27  
Old 23-11-2018, 03:38 PM
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Excellent.
Just check for me the number of teeth on your worm gear (you can do it by turning worm by hand and count the turns needed for RA axis to make 360.
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  #28  
Old 23-11-2018, 04:00 PM
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Quote:
Originally Posted by bojan View Post
Excellent.
Just check for me the number of teeth on your worm gear (you can do it by turning worm by hand and count the turns needed for RA axis to make 360.
I wont be able to do that until around 10/12 as it is in Sydney and I am at Tabby for a while...
You should see the dust here ..really strange...
Alex
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  #29  
Old 24-11-2018, 08:01 AM
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OK.
Some time ago I made electronics for my EQ3, it fitted inside DEC compartment next to counterweight shaft, see attached image.

I am still missing timing pulleys (1:4, with 48, 12 teeth or some other suitable combination) for T2 belt (which I have) transmission, so I will simply print them with 3D printer, this should be OK for wide fields. Hopefully the larger one will fit to your mount, and you will be able to fix the motor with suitable bracket.

If your mount has 144 teeth worm, I do not have to change firmware for Motorola processor used here.
It is certainly possible to do the same thing with one of small Arduino or digispark processors (plus stepper driver board), but this is almost ready and tested, so....
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Last edited by bojan; 24-11-2018 at 08:43 AM.
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  #30  
Old 24-11-2018, 08:06 AM
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Thank you Bojan.
Alex
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  #31  
Old 24-11-2018, 08:42 AM
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If you are not happy with printed pulleys, you can always go to ebay and get them from there.
60 teeth
or here for more variety.
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  #32  
Old 25-11-2018, 07:28 AM
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Here you go.... 60 teeth timing pulley, it fits pretty good to belt (subject to star test of course).
I found metal one for motor +(15T) so 1:4 transmission is now complete.
Now I'm just waiting for your confirmation on worm gear number of teeth (I am fairly confident it will turn out to be 144) and I have to sort out that Sharp laptop (to be able to program the processor for stepper driver).
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  #33  
Old 25-11-2018, 10:31 AM
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Thanks Bojan but please you worry me that you are going to so much trouble.
As I mentioned I cant provide information re the worm gears until I return to Sydney...
Thanks again for your attention.
Alex
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  #34  
Old 25-11-2018, 10:35 AM
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Quote:
Originally Posted by bojan View Post
If you are not happy with printed pulleys, you can always go to ebay and get them from there.
60 teeth
or here for more variety.
I favour function over form ... it can be made of cardboard if it does the job...
Alex
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  #35  
Old 25-11-2018, 11:01 AM
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Quote:
Originally Posted by xelasnave View Post
I favour function over form ... it can be made of cardboard if it does the job...
Alex
Quite...
But it is also a matter of accuracy - so if you find an uneven tracking rate, you should replace this pulley with more precise one.
And it is not a trouble, really... I am doing a bit of experimentation for myself, so this is a good excuse
As for 144 teeth or not, let's wait till you are back.
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  #36  
Old 25-11-2018, 01:20 PM
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Hi Bojan,

If it all gets too complex I’ll suggest there is a simpler solution along the lines of a controller I made in the 1980s using just two CMOS ICs and a handful of components that fitted in a tiny box. You can solder it on a prototyping board (hard way IMHO) or use wirewrap, this is quick and easy.

In essence ... wire up a CMOS 7555 timer with RC components and a pot as Alex suggested to give a nominal tracking rate variable by +/- 50% and feed that into the STEP input of a stepping motor controller chip. Wire to motor and power supply with a diode for reverse voltage protection and a fuse in it in case something is shorted. For the variable resistor use a decent Bourne wire-wound 10-turn type, not the rubbish from Jaycar as these fail rapidly.

You can add some hardwired logic for fast/slow push button from a handset if so desired.

The RC circuit will be good enough for visual since there’s no attempt to correct for PE or add autoguider inputs (which are feasible BTW).
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  #37  
Old 25-11-2018, 01:39 PM
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Hi Nick,

Yes, I am fully aware of simpler solutions (I was using Signetics 555 timer in exactly the same configuration and for the same purpose back in '80es), but now this is simpler for me because I already have the circuit (actually, couple of PCB's) from before.
Also, my firmware accepts input from buttons for tracking corrections so... here you go.
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  #38  
Old 28-11-2018, 07:59 AM
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I tried to read processor (Hynix GMS97L51), no luck - my Willar programmer does not have this processor on the list, and for any other C51 it says "ID error".
Funny thing - "L" in GMS97L51 means it is low-voltage version, so it is not supposed to work at supply voltage above 3.6V.. and it is on 5V in Dual Axis controller !!
Very strange - but I am not surprised after my experience with my Dual axis controller that came with my LXD-75 (I wrote about this saga couple of years ago).
Anyway... unless I obtain the hex listing for this paddle (so I can program the new processor), it will have to go into storage to wait there for better times....
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