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Type: Posts; User: Greg Fill

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  1. Replies
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    Poll: Quote: Maybe the complete circuit board could be...

    Quote: Maybe the complete circuit board could be designed by one of our budding young electronics nerds on the Zone.

    OK I am neither young nor a nerd but I can look into putting something...
  2. Sticky: Presenting my design - I got sidetracked playing...

    Presenting my design - I got sidetracked playing with the Cypress PSOC. If you are into micros the PSOC melds configurable analog and digital blocks with a nice fast processor. I have a working...
  3. Sticky: I am not familiar with the Atmel parts but you...

    I am not familiar with the Atmel parts but you may find that the comparator may be too slow. You may run into the same problem I have with the Cypress PSOC and the PIC micros that have onboard...
  4. Sticky: Tachus42 I looked at your schematic using a...

    Tachus42 I looked at your schematic using a 74HC244 as a FET driver. You may want to consider using a 74AC244 instead. The drive current of a normal HC part is about 5 to 6 ma. / gate output. A...
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    I tried three times but I have had no luck in...

    I tried three times but I have had no luck in downloading a valid file. I tried both English manuals and both are flagged by Winzip as an invalid archive. I opened the zip using Word and I do see a...
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    I was able to download the file but after it...

    I was able to download the file but after it completed Winzip said it was not a valid archive. I will try again.

    Cheers

    Greg
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    Yes for a small signal diode the 1N4148 is a...

    Yes for a small signal diode the 1N4148 is a great little workhorse. The LM324 won't be a problem it just may be a little slow. The good part is that the current in the winding changes slowly as...
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    Tachus, after I sent my message I downloaded your...

    Tachus, after I sent my message I downloaded your PDF. LOL It's uncanny how similar our schematics are. The AC current measurement circuit you used is what I used previously. Except I find the LM324...
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    Thanks tachus, yes I am aware of the current flow...

    Thanks tachus, yes I am aware of the current flow :-). The current direction is not a problem and it depends on the decay mode the bridge is operating in. In a SLOW DECAY mode the sense resistor...
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    I cannot see what you guys are doing because I do...

    I cannot see what you guys are doing because I do not have Eagle. I use Orcad. Here is a PDF of the discrete bridge drive circuit I am using now on my design. As you see the high side MOSFETS are...
  11. Sticky: Thanks that makes sense ES. The motor will...

    Thanks that makes sense ES. The motor will resolve its final position based on commanded number of steps, direction and the encoder feedback. I guess there is probably no need to set an acceleration...
  12. Sticky: I too have been playing and have completed a PIC...

    I too have been playing and have completed a PIC based microstepping controller that I will be sharing shortly. I am just finishing up the Visual Basic front end that allows it to be programmed from...
  13. Replies
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    Chuck Even though Allegro calls the A3951 a DC...

    Chuck

    Even though Allegro calls the A3951 a DC pwm motor driver it can be used as a bipolar stepper motor controller. A bipolar stepper is actually just a two winding DC motor. Two A3951s will be...
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    Chuck A design for the A3951 can be drawn up...

    Chuck

    A design for the A3951 can be drawn up but I think the A3951 has been discontinued. What is your suppliers price and how many does he have? You may not want to go down the path of...
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    There is a large inrush and break current that...

    There is a large inrush and break current that has to be considered when using relays to control motors. Most contacts are rated with a resistive load rating and a motor/inductive load rating. The...
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    If the person has a patent on the device then it...

    If the person has a patent on the device then it does not matter how simple the device is you cannot distribute it. If the circuit is so obvious that any person skilled in the field could design it...
  17. Thread: Whaaaaa???

    by Greg Fill
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    Thanks Mariss, I finally got around to your...

    Thanks Mariss, I finally got around to your diagram. Yes I see what you are doing. It will work with an optical sensor but not the stepper motor encoder. Unlike an optical sensor once you stop...
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    quote:...

    quote:
    --------------------------------------------------------------------------------

    My current plans are to support full step, half step--jumper selectable for each axis. Any comments?

    Yes...
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    I used a PIC16F873 as I have quite a few of them....

    I used a PIC16F873 as I have quite a few of them. I thought of using a PIC16F630 in the final design to save a few dollars. 1 micro is needed per axis. I use ORCAD for both capture and layout. I...
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    I lost my first post attempt because it did not...

    I lost my first post attempt because it did not like my jpeg file with the .jpe extension.

    I am not involved with the Opensource DIY controller yet but here is a picture of my design so far. The...
  21. Thread: Whaaaaa???

    by Greg Fill
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    Mariss instead of writing your reply in the post...

    Mariss instead of writing your reply in the post reply box use the post reply button on the last message to respond and attach the file through the enhanced menu. A cross coupled SET - RESET FLIP...
  22. Thread: Whaaaaa???

    by Greg Fill
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    Yes I messed up it does provide hysterisis. In...

    Yes I messed up it does provide hysterisis. In my defense it was late at night :-), but I feel hysterisis is not necessary with the slow opamp. What we need to do is to ensure is when we turn the...
  23. Thread: Whaaaaa???

    by Greg Fill
    Replies
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    I like what the OZ2 circuit shows - the PCB right...

    I like what the OZ2 circuit shows - the PCB right on the back of the stepper. Caps may be a good idea if you are going to use a comparator. With a real comparator the edge transitions will be very...
  24. Thread: Whaaaaa???

    by Greg Fill
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    Feedback, this is good. Actually with the LM358...

    Feedback, this is good. Actually with the LM358 the edges are fine and there are no multiple edge transitions. It helps that the output slew rate of the LM358 is so low (0.1 v/us) but this also...
  25. Thread: Whaaaaa???

    by Greg Fill
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    You would add a resistor from the output back to...

    You would add a resistor from the output back to the input if you were using a comparator. In this configuration using an opamp if you added a feedback resistor you would be reducing the gain of the...
  26. Thread: Whaaaaa???

    by Greg Fill
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    3,491

    Thanks Bent I did figure out all the same things....

    Thanks Bent I did figure out all the same things.
    Well it goes to show that nothing is really ever new. Usually someone has already done or designed the same thing. It is a good article and people...
  27. Thread: Whaaaaa???

    by Greg Fill
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    Thanks Al, I figured out the circuit myself but I...

    Thanks Al, I figured out the circuit myself but I guess there are many ways to do the same thing if you know what you are doing. I was interested in your link to see how they made a jogger but the...
  28. Thread: Whaaaaa???

    by Greg Fill
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    3,491

    I have the circuit on my DIY stepper driver...

    I have the circuit on my DIY stepper driver board, I'll post the schematic once I do a cut and paste of the appropriate page and figure out how to attach a PDF file in the forum.

    The BOM (Bill...
  29. Thread: Whaaaaa???

    by Greg Fill
    Replies
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    Just for information - because a Stepper motor...

    Just for information - because a Stepper motor acts as a generator when rotated it makes a good low cost quadrature encoder for jogging inputs. Take a 200 step motor from a old 5 1/4 inch floppy,...
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    It looks like a magnetic encoder. Check the...

    It looks like a magnetic encoder. Check the black ring to see if it is truly a magnet. The ring is magnetized so that it has many North and South poles side by side. The magnet triggers the hall...
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