Hi guys. I've just pulled a couple of printers appart and found three motors inside each. 2 look like the ones in asimovs pictures and the other looks like a cilinder. I got four to work by connecting power to them. The cilindrical ones when I connected them you could hear them working but they didn't turn. this happened to both motors from two different printers. Are they broken or do they need something else?
a stepper motor turns by signal sent to the outer magnets saying turn on. when they are on, the inner magnets turn to align with the outer magnet. ie north poles to south poles etc.
to get it to turn you have to send a series of pulses (square waves) to the motor saying first set of magnets turn on so that you are a north pole, the other magnet at say 90 degrees to the first one will then be turned on to be north after the first one hass turned off.
that way the inner magnets chase the changing outer magnets around the circumfrance.
hence the need for a controller to send differenet signals to the motor. putting a 12v dc voltage to the motor will simply align the magnets in one direction and it will stay there. it needs to turn on and then turn off.
I have got my contacts who import from china to have a look on the chinese combined stepper motors and reducers.
If these can land for less than $75 dollars then it starts to make the whole motorized tracking and focussing dob design less than $500 which is where we want to be
You can make them. basically you have to be able to pulse square waves. Controllers can be bought from Jaycar. cjeck your local store, RS components.
I have just bought and it arrived today, a usb stepper controller. plug it into the usb port, attach 12volts to power the motors and now i can control 3 x stepper motors separately from code thru the usb port.
I will review it tonight and let you know
cost $85 + freight + gst.
For $85, i could not be bothered making myself, but it can be done
I await your report. As I'm in my final stages of finishing my mirror, my next step will be to motorise the scope I make and to make a trcking platform.
bought my piece of 1.2mm aluminium sheet to cut out my 560mm diameter disc to attach to the underside of the top base of the dob! Should smooth out the XY movement. There should be enough left over to help make the focusser attachment for attaching the focusser to the scope.
The USB stepper motor controller also arrived, but have not had a chance to try out.
First project will be to try and turn the crayford focusser with the 1.8 degree full step stepper motors. Will have a look at 1/2 step ie .9 degree and see what level of adjustment that gives me.
I will have a good go over the weekend and update as i go. I will even make a video i think!
this is the pdf link of my summary of where we are at re costs.
I have not finished entering, it is a work in progress. Mick may not want to adapt his dob buggy, el may not want to put his focuser in with this project, and wombat may copyright his bearing and not want to sell.
This document is purely a summation of ideas we have all been throwing around, it may amount to nothing! All parties would have to be happy, before any official selling prices would be announced.
I just had one of those moments...
Why could we not adapt and use the RA/DEC motors and Hand controller used for EQ mounts, you would need a wedge under the dob.
Like this one. http://www.haven.k12.pa.us/orfft/wedge.html
Is this a workable solution.
The other option is to get an Autostar 437 or 436 controller and use it to control the motors. Not sure if the Meade Autostar needs Meade motors or not.
I have had success driving all three stepper motors with the USB stepper motor controller. Very easy to install the drivers for Windows XP pro. I also copied the runtimes and library files so that i can write my own tracking and focussing program in .net
I looked hard at everything and thought how do i work out what wire (there were 5 on some and 6 on another) activated which coil????
found a link that i have just added to the thread.
Basically, you find the common wire as it has half the reisitance compared to the other pairs of wire, and then by putting 12v on that common wire and grounding the other wires one by one, you can work out the sequence or order of coils. I have made the decision that clockwise is forward and anti clock is backwards, so therefore if you find that it is running backward, swap wire 2 with 4 or 1 with 3.
had bought my 12V 7AH battery from jaycar a few weeks back, soldered some terminals on and connected to controller. connected to computer, loaded up the little program they include with the controller, pulled the wires for the coils out of the power area (when i was deciphering the order) and put them into remaining 4 holes.
set the number of steps and pressed "forward" and voila, it turned beautifully.
$85 plus freight + very satisfied = very good value!!!!
I have no worries at this stage recommending. I will be attempting to direct couple one of the steppers to the crayford focusser tomorrow and get a feel for how accurate 1.8 and .9 degree steps are.
David, are you saying the usb controller can do microstepping... i did not think this was its function. If it does then its worth the money. How are you on the .net programming side of things?? have you got algorithims you can use or are you going to write your own.
there were three speeds on the little interface they included with the kit, whether that is microstepping, 1/2 step and then full step. i will check.
With .net, i am happy that as long as i have the library link to add to my own program, and therefore i am hoping i can send whatever series of pulses to whatever coil, then i will control the stepping in 1/2 and full.
not sure if i can control the level of voltage ie send sine or cosine voltages to do microstepping, but hope to find our by end of day.
my ultimate aim is to write in .net an interface for my telescope that i can use from the internet. including controlling the movement, focussing and also using the image properties ie exposure times, maybe even auto focussing thru the software.
lots of mini projects in that!
webcasting an event would be a fantastic forum tool and would be a great educational thing.
Hi Dave. Very interesting thread you have here! I went down this road your travelling (or tried to) a few months ago. I'm not as brainy as you so I got someone else to fiqure it out for me as you know. Anyhow, I fitted the motor to the EQ mount yesterday. It drives....but how successfully I'm not sure yet (crap weather) As I told you, it takes rather big chunky steps & you can feel it vibrate thru the whole mount every time it takes a step. Not sure what the answer is to getting it to run smoother..I dare say if it were possible to make this motor take smaller steps...the builder of the controller would have done so?? Or isn't it that easy??
I would also support a localy made product. My concern is about not needing to reinvent the wheel if possible. One other thing you could look at is possibly trying to use a standard for your communication protocol so that you application can work with any Sky chart program to do a drag and drop. Also standard that would alow it to work with DSC's lilke the Argo Navis. I too am very intrested in programming, but have not done any since leaving uni. Though i am confident i could pick it up, specifically though i could probably help you code specific algorithims for doing specific functions.
Have you got an overall block with modules for the program are you just going to write bits and pices as you go.
yes, i am also worried about reinventing the wheel.
if there was a $300 system that did the lot, then i would have bought it.
I intend to make the code standard, I just have to investigate argo etc to see what they do and how they do it.
Some guys do not take the laptops, so i spose handcontroller compatibility is something to thinks about.
I try and use web services as i go so that i can keep the code for other stuff. so whilst i am not a purist, ie i just want to get the thing working not make it ultra pretty, i understand that a sense of structure and neatness has its advantages
