I am in the process of building a 2" shaft pillow block mount. Building the mechanical parts to the mount is no problem but electronics is a mystery to me.
So where to start with understanding this subject. Any books/sites that are good for understanding how to read a circuit diagram, I guess is the sort of thing I'm after.
Pictured is a 10" 359 tooth Byers drive that will be the RA gear for the mount. I have a 12V stepper motor with it. What do I need to get this motor powered up to track. It comes with 'instructions' pictured. My vague understanding is supply 12V power and it will do its stuff....correct
I think you are going to need a stepper motor controller. Have a look at this site as this controller is already set up for astro and will interface to astro software through ascom: http://www.astroeq.co.uk/tutorials.php
Gday Matt
Do you have a better piccy of the motor and its
markings ( or a clear transcription ).
Looks like its a 6 wire stepper in which case a dedicated controller is required to run it. Lots of available choices there but more info reqd on what model it is.
It's a Hurst motor Model ABS, 12VDC, 4 1/2 W.
6 wires that are black, red,white, blue, black and white stripe, blue and white stripe.
Looks exactly like the Hurst Losmandy steppers that I have on the Gaunt mount.
Matt
Edit: it is exactly the same model as the Losmandy stepper.
Gday Matt
I meant the stuff next to the part number etc
Those nos give you access to the internal resistance details and gear reductions, all of which you need to size the current capacity of the driver and the reqd stepping rate.
but based on it being used by the losmandy,
could you just get an old losmandy Hbx etc to drive it???
( Edit. Hmm, perhaps not, as it looks like the losmandy
controller uses a crystal, so will be fixed for the
losmandy wormwheel tooth count, and the G11 uses 360
whereas yr gear is 359 )
Thanks Andrew.
I forgot to mention that there is a gear reduction on the worm and stepper motor. My quick count gives 20 on the motor and 60 on the worm gear giving a 3:1.
The Losmandy steppers go straight to the worm with no reduction so I don't think the Losmandy drive will work.
I think a trip to Jaycar is in order for a 6 pin RJ11 plug. I'll take the motor and instructions along. The guys in my local are pretty helpful...going to ask what to do with all this on CN and see what turns up.
Ed sells these with a 110v synchronous motor which I think is just plug it in and it works. Ed reccomended a 12V for me in Oz (I rang him up) and I hoped it would be plug and play but it seems not.
Might be making a phone call to Ed Byers again....
You currently have a stepper, so will need a stepper driver of some sort to run it. These can be made to run at any speed you want ( if the motor is capoable of it ) using a PIC type driver.
The main thing is to see how fast it is going to need to run
ie the motor you list has a 150:1 reduction gearbox built in already
so with a 3:1 reduction on top of that, you have a 450:1 reduction driving a 360 tooth wormwheel, so its not going to go real fast at the output axle :-)
Hurst do sell different motors that you just apply voltage to and they run at a set speed, but they are a different model type.
IIRC, the early Meades used these, and you needed to buy a specific version, as they were pre wired to go CW or CCW at a set speed.
Now I'm getting somewhere I think. Have found AWRtechnologies in the UK which has what I want ...but at a price. Will put in a link when I'm at my computer. http://www.awrtech.co.uk/ih/ih_spec.htm
As I mentioned earlier I have an EQ6 board and simple hand control. The EQ6 has 180 teeth. If I put a 2:1 reduction gear set between my stepper and worm gears that should be close to tracking should it not? Thinking out loud here. As an edit I just thought there are gears on the EQ6 steppers so will have to take those into account too.
The EQ6Pro has a 1.8deg stepper ( microstepped at 64x ) driving a 12-47 reduction belt, so it immediately becomes a problem.
You could always use EQMod to drive it, as you can configure that any way you want, but not sure if your motor is suitable for microstepping.
Also, your stepper already has a 150:1 gearbox built into it, and you mentioned having a 3:1 drive between worm and motor.
With a stepper, you need to work out the steps per arcsec ratio when comparing controllers, you cant just look at the wormwheel toothcount.
I don't know if this is of any use to you or if you are already aware of this. But I thought it may give you some ideas on controller boxes and potential software to operate it.
Jaycar used to sell a stepper controller kit. I think it is discontinued. I used it in one of my portable solar eclipse mount motor controls. It's only for unipolar stepper motors.
There are many off the shelf printed circuit boards available on ebay that have everything you need. These are made in China and cost $1-$5 each. You only need a few of these -
This one allows microstepping, forward reverse, full,1/2, 1/4, 1/8 times microstepping selectable and should drive your motor without an intermediate driver. The driver cards fully populated with components can be purchased very reasonably from sparkfun who support the designer to produce more of this stuff. You can also buy ripoff versions of this board on ebay for a few dollars.
This boards takes a simple pulse generator input or can be controlled from a computer via usb. It is handy to be able to run a drive without having to have a computer attached.
Ta Gav and Joe. I have seen Mel Bartels site but really don't want to spend that kinda cash. Same goes for the AWRtech parts. Tomorrow I will get into my local Jaycar and see what they have.
An email to Ed Byers is in order too. I have a 3:1 gear reduction on the stepper and worm...most gears are 4:1 which would make sense, wonder if this is an error.
My ideal is a simple handset with slew controls....no computers in sight....except encoders and Argo Navis.
My ideal is a simple handset with slew controls....no computers in sight....except encoders and Argo Navis.
Matt,
That's exactly what I have described. Completely standalone. You can build it for about $25 - $50 in parts depending where you shop. Jaycar don't have anything that will drive that Hurst motor. Set the timer to drive siderial at 1/8 microstep, then slew at 1x gives you 8x slew speed.
My lightweight mount has to pack into a suitcase and fly around the world so the controller is completely stand alone. My lightweight mount is controlled by the old discontinued Jaycar stepper controller. But I am going to build a new control circuit based on the same circuit as I have described here with pulse generator and easy stepper controller. The power supply, easy stepper card & pulse gen cards are so small, I can build them into the housing of my mount and eliminate the whole controller box.
If your circuit is driven by a pulse generator, you can adjust the frequency to any speed you need. Then 3:1 / 4:1 ceases to matter.
If you go down this path, I can give you some info how to wire it up to slew etc.
The alltronics circuit is an unipolar stepper control similar to the old Jaycar one. The Hurst stepper motor you have is a bipolar and needs a different type of drive circuit. I am not sure the Alltronics driver will drive the Hurst motor.
The first link is how to make and what is needed (DIY). All up the parts may reach around $50 or so. The instructions and parts list is for the controller and hand control unit.
The software is optional and the 'scope' software can now be downloaded for free. From links within the website.
The other links are just information or examples. Yes bbsastrodesigns will give you a custom built option if you wish and at a price. But there is enough info there for your own DIY project.
Cheers
Gav
Quote:
Originally Posted by MattT
Ta Gav and Joe. I have seen Mel Bartels site but really don't want to spend that kinda cash. Same goes for the AWRtech parts. Tomorrow I will get into my local Jaycar and see what they have.
An email to Ed Byers is in order too. I have a 3:1 gear reduction on the stepper and worm...most gears are 4:1 which would make sense, wonder if this is an error.
My ideal is a simple handset with slew controls....no computers in sight....except encoders and Argo Navis.
If your circuit is driven by a pulse generator, you can adjust the frequency to any speed you need. Then 3:1 / 4:1 ceases to matter.
As per before, you still need to find the pulse rate the motor will be required to run at to give sidereal tracking with the current gearing. ie you may need to change the gearing between motor and worm to enable the motor to operate correctly over the range you want ( if you want to microstep etc ).
Thanks Gav, Joe and Andrew. This is going to take a bit of time for me to understand what I need…working for a living gets in the way of ATMing…will get there eventually
DIY is definitely my preferred way. Gav a dumb question if I may…are the Bartels parts all easily available to buy?
