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Thread: Drive a 1.8 degree stepper at 1 RPM

  1. #193
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    I was thinking I would need 4 FET's with dides to control the 2 motors in forward and reverse. I really don't want to start changing the PCB so an addon if it will work would be the best solution.
    I am also going to get motors with an encoder shaft so I can fit the origional encoders for campatability.


    Ceefna

    Last edited by ceefna; 01-19-2012 at 05:42 PM.


  2. #194
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    Here is the video James, did my best really don't like talking on film
    Let me know if it is ok.


    Also here is a modified version of the stepper timing calculator.


    Ceefna

    Attached Files Attached Files


  3. #195
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    Nice going on the video and calculator!



  4. #196
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    Wow! What a great video! I'm totally blown away... I've already commented on youTube, facebook and posted it to the Linistepper facebook group and I've started a page for it at: techref.massmind.org/techref/io/stepper/linistep/equatorial.htm

    ceefna, I've taken the liberty of publishing a slightly modified version of your spreadsheet on google docs (see the page above for a link to that) and I've built a Javascript version of it on the page which does more or less the same thing.

    I'm hoping others will be interested and perhaps will want to order the PIC pre-programmed for their mount.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


  5. #197
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    Hi James, the page is great your Java script calculator is brilliant, good idea to show the line of code so people don't get confused with decimal places.

    Have a look at your youtube comment I think you have put Linistepper,corn

    Still looking for a way to get more power out of my telescope motor driver.

    Ceefna

    Last edited by ceefna; 01-22-2012 at 01:06 AM.


  6. #198
    Registered James Newton's Avatar
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    Quote Originally Posted by ceefna View Post
    Hi James, the page is great your Java script calculator is brilliant, good idea to show the line of code so people don't get confused with decimal places.
    Thanks! I'm hoping people will start building these and request custom programmed PIC's with that line.

    Quote Originally Posted by ceefna View Post
    Have a look at your youtube comment I think you have put Linistepper,corn
    Yeah, youTube will NOT allow a URL in the comments. rn looks enough like m to get away with it, but they still won't allow anything.co so a comma is necessary. Hopefully, people will just "autocorrect" from what it looks like.

    Quote Originally Posted by ceefna View Post
    Still looking for a way to get more power out of my telescope motor driver.
    Wouldn't it be pretty easy to just scale the camera version? The Linistepper will drive a much larger motor... up to a couple amps... if you add a CPU cooling fan. And if you need more, you can use the Linistepper board to produce step pulses for a larger driver, like the SLAm or even a Geckodrive.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


  7. #199
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    Great thread. Very impressive results. One of my sons isn't much interested in CNC machining, but this related use for photography has definitely inspired him.



  8. #200
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    Quote Originally Posted by James Newton View Post
    ...
    Wouldn't it be pretty easy to just scale the camera version? The Linistepper will drive a much larger motor... up to a couple amps... if you add a CPU cooling fan. And if you need more, you can use the Linistepper board to produce step pulses for a larger driver, like the SLAm or even a Geckodrive.
    I tend to agree.

    That Celestron engineering telescope driver is a commercial product and I don't think it's right (for me anyway) to really help in reverse engineering it, even if Ceefna just wants to modify it to run a bigger motor.

    Ceefna, exactly what features does that Celestron board have, that you need to keep using it as the "brain"?

    And have you talked with Celestron about if it is possible to run a larger motor with their board?

    Normally the servo drivers are specced on max current, so it's quite possible you could use a larger physical motor with more torque, but one that draws the same current so the Celestron driver will drive it without modification. For instance a large 18v 1 amp DC motor can have a lot more power than a small 12v 1 amp DC motor (but both can work from a 1 amp driver).



  9. #201
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    Hi, the celestron brain has the coordinates of over 4000 astronomy objects in its memory. You align the telescope to 2 stars and input their positions. From this the software knows where the telescope is pointing.

    You choose from the list of objects in the controller e.g The star Vega and the scope will move to where Vega is in the sky. Now without the brain and feedback from the encoders that would not work.

    When you are wanting to take pictures of deep sky objects that you cannot see through the telescope only with long exposure then you have to be sure you are pointing in the right place.
    I have found out that some of the larger Celestron scopes also have the L293DD, they use Pittman 8000 series motors so maybe this could be an option.

    James, see what u did with the YouTube link. Duh, I feel stupid now.

    Ceefna

    Last edited by ceefna; 01-22-2012 at 05:13 PM.


  10. #202
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    Unhappy Need your help Roman

    Hi Roman,
    I appreciate all the help you gave me with the camera tracking mount. It works like a dream. I have a problem that I could do with some help on. I know you said it wouldn't be right to help me modify the motor drive board but would it be ok for you to help me fix it?
    I am such an idiot, I was testing the logic supply voltage on the L293 between pin 20 and ground pin 16 on the schematic)and I had my multimeter plugged into amps and shorted something, duh.

    The board still works, but the is a 10 second ish delay before it starts to track. Once tracking if I slew the motor to the right at full speed it takes about 10 seconds to start tracking again but if I choose a slower speed(you get 1 to 9) say 8 or below then it will track immediately. Its like it is having to re-charge/re-buffer before it starts to track again.
    Now if I slew the motor to the left then it will start tracking again almost immediately. so its a problem moving right.
    I have found a schematic for the board but I am not 100% sure that it is correct as it is not a professional one, here is a link.The PIC's on the board are 16F876A and the L293 is 20 pin so the schematic is wrong
    http://www.dd1us.de/Downloads/Schema...oard%200v2.pdf

    I have checked the input to the L293 on pin 7 (which is the motor turn right pin) with a led and it flashes away ok when slewing the motor as soon as the button is released the motor stops and should start to track straight away but nothing happens. You can see the led is dimly lit for about 10 seconds then it jumps into life and starts to flash as it tracks.
    I hope you can understand this and have 5 mins to have a quick look at the schematic.
    I think the L293 is ok as from my test it is not getting the signal to drive the motor from the 74HC240D for 10 seconds but what feeds the 240D. Could this be at fault? is it a lost cause trying to fix it? I am not sure I will be able to find a replacement.
    Thank you for all your help

    Ceefna

    Last edited by ceefna; 02-25-2012 at 05:36 PM.


  11. #203
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    I did a circuit on this subject for a customer
    microHobby.net - Clock driver for Sparkfun EasyDriver breakout



  12. #204
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    Quote Originally Posted by hspalm View Post
    I did a circuit on this subject for a customer
    microHobby.net - Clock driver for Sparkfun EasyDriver breakout
    Nice, but the source code on that page seems a bit garbled... I don't see how the microstepping can possibly work as written and there are #includes that don't have files associated, and #defines that are run together on one line.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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Drive a 1.8 degree stepper at 1 RPM
Drive a 1.8 degree stepper at 1 RPM