AstroEQ, what i was looking for.

[Chris]

Has anybody got any data on how accurately an eq5 will track assuming its all set up correctly? Im just wondering as i would like to compair this modification to one with a comercial goto upgrade and need a baseline to aim for, or more importantly so i dont go chasing my tail looking for improvemets that just are not possible. I would like to get this tracking as accurately as possible, but realise i will be limited by the mount itself.

Simon

I don't know about the goto EQ5 but I could only get 45 seconds at 480mm focal length from my old EQ5 with the basic dual axis drives, I know other SGL members who have had much better luck (skill) with the aforementioned getting anywhere upto 2 minutes unguided at 1000mm focal length. But again I don't know about the EQ5 Goto or guided so probably not that much help.

Great thread, I'll be following with interest:)

[simonmc]

Starfox,

Cheers, that gives me a starting point of what to expect.

Simon

[simonmc]

Hurrah, the motor controllers turned up today. There are really small and should be ideal for this. As sods law would have it i have been busy today so that not really been able to get much done on this project, but i did manage to rebore the pulleys and tidy them up a bit. Hopefully tomorrow i will have a bit more time to finalise the mechanics and then move on to the electronics. Couple of pics.

Motor Controller. (two of them!)

Pulleys

Simon

[simonmc]

Well got the mount pretty much finished for now, just some small bits on the tripod to finish up so its now time to start on the electronics. Hopefully that will be tomorrow when thats all done. Some more Pics.

Dec motor and pulleys

RA motor and pulleys

Mount on the not quite finished tripod

Well its starting to look like someting useful at least. I may have to look at the dec axis again as it seems a bit tight. Also i think that when i make the alloy mounts there are a few changes i will make to make it a bit more 'intergrated' and more robust, but want to hold off till its actually moving..

Simon

[JamesF]

Looks like a very neat job so far.

James

[simonmc]

Cheers James,

I still find it odd that all the paints match up even though everything came from different second hand sources. The colour has even started to grow on me, sort of reminds me of the all the old 60's test kit i used at college. Im also going to start having to think about cable management at some point...

Simon

[robjohnb]

My RA mount has very similar mod's!

Question, does the control SW you intend to use have micro-stepping for the stepper motors?

Regards, Rob

[simonmc]

That spookly looks like mine! What pulleys are those that you are using and where did you get them??

The AstroEQ does indeed use microstepping. Cant remember off hand if its 1/8 or 1/16 microsteps though. If you follow the links in this post to the software writers post in another forum he gives a weath of data.

Simon

[simonmc]

Just checked and its 1/16th microstep.

Simon

[robjohnb]

Haha! you are not alone in your endeavors.

The pulleys are 18/60 from Technobots (MXL025).

Does AstroEQ have a web site?

I've had a go at this method... http://soundstepper.sourceforge.net/

Not used it in vengence yet but basically working but being put off by how long it takes to set whole thing up outside.

Rob

[simonmc]

Rob,

Thanks on the info on the pulleys.

It has a wiki and thread on another forum. There are some links somewhere back in this thread.

Good Luck,

Simon

[simonmc]

Ok,

I have made a bit more progress whilst watching tele with the family. I have programmed up the arduino mega, and it seems to work on its own in CdC using eqmod. Only been playing but using the spredsheet supplied with the downloaded software my set up string is:- Synta synta (1281, 7372800, 53052, 16, 51200, 1)

I also set up the sketch to turn on legacy mode (as im using an arduino) and usehighspeedmode. Im still playing with the goto speeds, but really only playing as the arduino is not connected to the motors so all im doing is moving a reticule around the screen at different speeds!

The connections to the 2 pololu drivers should be as follows:-

driver1(RA) Mega pin

Enable 4

ms1 16

ms2 +5v

ms3 17

Reset A1

step 5

Dir 3

driver2(DEC) Mega

Enable 8

ms1 19

ms2 +5v

ms3 18

Reset A0

step 12

Dir 7

I still have to test this and hopefully will tomorrow, but the author said the connections looks right.

Simon

[simonmc]

Looks like i got it working with stellarium and eqmod using stellariumscope as well now. Cant wait to get the electronics all connected now and see how it all performs and learn abit more about eqmod.

Simon

[russellhq]

Has anybody got any data on how accurately an eq5 will track assuming its all set up correctly? Im just wondering as i would like to compair this modification to one with a comercial goto upgrade and need a baseline to aim for, or more importantly so i dont go chasing my tail looking for improvemets that just are not possible. I would like to get this tracking as accurately as possible, but realise i will be limited by the mount itself.

Simon

Guided or unguided? With my guiding set-up I average around ±1.6 arcseconds. Without it's about 10 times that.

Guided:

Un-guided:

[simonmc]

Ah thanks, more data. Thats really good, as in between doing family stuff and the shopping i managed to get this built:-

I still have to check it over before powering it. I have checked with the designer and most of the pins can be changed to whatever is better placed, apart from the step pins. So i moved some of the pins to line up better with the drivers and lessen the wiring. The caps are a little big but they where what i had to hand, and found some memory heatsinks and used one cut in half to keep the driver chips cooler.

Simon

[simonmc]

Well i had a bit of time yesterday, and managed to finalise the circuit and check the wiring so that looks good. Juggling free time is always a bit of a hassleI with a few active projects, a bigger family and business to run i'm discovering!!.

I also modified the arduino sketch to take into account my modified pin assignments. So all i have to change the wiring in the plugs for the motors and check the current limit on the drivers and i will be all set to start bench testing the mount.

The only nightmare i had was that my trusty Weller EC 1301A soldering iron decided to play up and switching itself off so had to resort to my soldering gun that i normally use for the car. I think i may now struggle to get spares for it. Fortunatly when this happened i only had to solder the (too big) motor power wires to the board. Hopefully i will be testing later on today..

Simon.

[simonmc]

IT WORKS!!!

Well sort of. I did have a couple of problems because i re-tasked the pins in the sketch and accidently used the pins used for the serial connection but that was easily rectified. If anybody else builds this i would recommend just using the pins that are the default ones in the sketch as downloaded.

I think its tracking 4 times to fast as the RA worm is taking 2 1/2 half miniutes to rotate a full turn but thats probably a variable in the software i have miscalculated. Just using the mount connected to stellarium through stellarium scope is good to watch though with it Goto'ing in the correct direction and matching the cross hairs on screen.

Also some mechanical problems showed their head. The DEC axis pulley keeps coming loose and the axis is still 'binds' a small amount but thats something i thought i would have to revisit.

All in all though, Stellarium is connecting and moving the motors and it is now a 'Mount' rather than a random collection of second hand parts and ebay bits!!

Now some debugging..

Simon

[simonmc]

Well after a load of double checking and not figuring out what was wrong, i changed the config string by a factor of 4 from what it should be and it now seems to track correctly. Now just a few more teething trobles to sort out with my cheap drivers and motor combination. I was being cheep and managed to get some A4983 drivers when i really should have got A4988 drivers. The A4988 has a low power microstepping mode according to the data sheet but it could also be that my versions of A4983 is also has a max current limit of 1A. It should be possible to up this a bit as my steppers are 1.7A. However another step forward..

Simon.

[simonmc]

I have improved the missed steps by shorting out R4 on the driver boards. This puts the chip into a fixed off time mode. All i need to do is change the sense resistors and that will up the current. That should fix the missing step problem. Now all i need is better eyesight as the comonants are surface mount. 5 years ago it would not have been a problem but now im getting to close to 40 it is!!

Simon

[Gonzo]

Simon, are you able to do a video of the all kit, ie: how it works etc.. ?

[Oily]

An ST-4 port isn't essential as the AstroEQ hardware/firmware requires EQMOD anyway to provide the telescope/mount control - so you can use ASCOM pulseguide for guiding.

Chris.

Hi Chris,

I have the AstroEQ from Tom and was wondering how would i set up pulse guiding in EQMOD using my webcam/guidescope?