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  1. #601
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    Feb 2007
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    33
    Quote Originally Posted by lucas View Post
    The row and colums are indicated on Steve's schematic, the sequence is the same on my PCB.
    Viewed from componentside and left to right:
    R4 R3 R2 R1 C4 C3 C2 C1

    These are very good DIY stepper drives:

    http://users.skynet.be/ldt/CNC%20ele...THB6064AH.html :cheers:

    Thanks Lucas,

    I will contact the seller,

    Best regards

    Terry

  2. #602
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    Jan 2010
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    Quote Originally Posted by terryd15 View Post
    Hi dk,

    I intend to use it with the rotary table indexer described on this thread and the experimenting I referred to will be in the program of the indexer, if as you say the board will drive a stepper it should be ok then as the indexer provides the logic?

    Regards,

    Terry
    Unfortunately, no. All stepper motor drivers are not created equally, so to speak. It's necessary to examine the details to understand what functionality is provided by a particular "driver" and what is not.

    The rotary table indexer circuit outputs step and direction signals which in turn are used to control a driver that is designed to accept step and direction signals as its input.

    The aforementioned L298 driver board is not capable of accepting step and direction inputs by itself. Rather, it only comprises the electronics that can energize two coils in one polarity or the other. Additional circuitry would be required to provide the logic that translates the step and direction signals into the proper sequence of coil energization and de-energization that will result in the desired movement of the motor. Other circuitry could also be added for the purpose of limiting the current drawn by the motor, or for microstepping, or other desired features.

    There is an IC called the L297 (that is designed to handle some of that functionality) which is often paired with the L298, however the board to which you linked does not have the L297 circuitry built in.

    As an alternative, theoretically you could modify the firmware of the indexer board to handle the required logic, however my understanding is that the source code for the indexer has not been made available, and so that task would entail designing and coding all of the logic from the ground up, which would be a major undertaking.

  3. #603
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    Jan 2005
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    Quote Originally Posted by homerandmarg View Post
    Hello Lucas, Kwackers and Jhovel,
    If I could ask a couple of questions:

    To Lucas, I have a query about Q3, the transistor for the sounder. I note that you have it orientated flat side facing the 7805. This places the NPN emitter pin to the +5V rail. Is this correct?
    The silk for the transistor is correct.
    All 3 are BC337, for Q3: pins from top to bottom C B E (viewed from component side). Emitter is connected to ground.

  4. #604
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    May 2006
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    Hi Simon, I'd go with post #33 (I'd probably actually tried those to make sure they work). I haven't checked the circuit diagram so can't comment - but that was drawn from the finished circuit. (I built it on a breadboard then drew the circuit once it worked...)

    My pcb layout was checked with the Farnell keypad, beyond that...

    Most keypad problems can be resolved by considering the keypad to be two sets of 4 wires.
    If the keypad is rotated 90 degrees (i.e. the rows and columns are swapped) then swap the two sets wires over.
    Then if the keypad is flipped top to bottom flip over the 4 row wires.
    Finally if the keypad is flipped left to right flip the 4 column wires.
    (It helps here if the keypad cables are two reversible 4 pin plugs...)

    If I knew then what I know now I'd have added the ability to reprogram the keypad from the software! (Perhaps if I get some spare time)

    Cheers,
    Steve.


    Quote Originally Posted by homerandmarg View Post
    To Kwackers: Looking at your schematic, the pin allocations for the keypad has me confused. The schematic at post No. 35 has different pin allocations to the diagram on post No. 33.

    For example Post No.33 shows that connecting pins 22 & 27 yields (1) but post No. 35 shows its pins 30 & 19 to get (1)

    Simon

  5. #605
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    Apr 2007
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    10

    Talking winning

    Hi guys
    My indexer is up and running and just needs boxing up.

    I must thank all of you who took the time to help me get to this stage it is most appreciated.:cheers:

    Thanks especially to Steve Ward for software and support and to Lucas for the board design.:cheers:

    I will try and add photos when its complete. :wave:

  6. #606
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    Feb 2011
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    Thanks Steve & Lucas,

    It pays not to do stuff late at night when I should really be getting some zzzzzzzz!

    I have a cheapie keypad (Same as Jhovel) and the pin placement seems to follow no known standard! With the keypad you used, the keys can be labelled at will and so it opens up many combinations. Should have gone with that!

    Lucas, I never doubted you! Like I said, late at night things seem a little fuzzy...

    On another note, I'm planning on using this stepper driver with a nema 23 stepper motor for my 8 inch RT.

    Single Axis TB6560 3.5A 2 Phase CNC Stepper Motor Driver Board Controller | eBay
    It says the inputs are optically isolated and so needs input resistors. It states a 1K resistor for 12V controller signals, so could I get away with a 500 ohm from the controller given the approx 5V outputs? That's about 10mA output, would the chip do this or should I add a couple of output transistors to drive the output and keep the current low

    Thanks,

    Simon

  7. #607
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    Roughly speaking 12v and 1k is around 10mA.
    (12v minus 2v for the led forward voltage drop divided by 1k).

    So for 5v you need 3/0.01 = 300, so call it 270 ohms.

    10mA is well within the current source/sink capabilities of the chip so I wouldn't worry.

  8. #608
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    Quote Originally Posted by kwackers View Post
    Roughly speaking 12v and 1k is around 10mA.
    (12v minus 2v for the led forward voltage drop divided by 1k).

    So for 5v you need 3/0.01 = 300, so call it 270 ohms.

    10mA is well within the current source/sink capabilities of the chip so I wouldn't worry.
    Once again, thanks Steve!

    Simon

  9. #609
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    Hi,
    I have a 4" rotary table similar to this one. What size motor can I get away with, does anyone have any suggestions. ARC Eurotrade suggest a 180 Ncm stepper, That seems a bit overkill to me, what have others used on this size table (1:72 worm ration).

    Besrt regards
    Terry

  10. #610
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    Quote Originally Posted by terryd15 View Post
    Hi,
    I have a 4" rotary table similar to this one. What size motor can I get away with, does anyone have any suggestions. ARC Eurotrade suggest a 180 Ncm stepper, That seems a bit overkill to me, what have others used on this size table (1:72 worm ration).

    Besrt regards
    Terry
    You could certainly use a smaller motor, probably I'd go for the same 'footprint' but half length.
    (Although unless you need a smaller one I'd be inclined to go with the 180).

    I use a 180Ncm one on my 4 & 6 inch tables (1:90) and I often bolt the 4 inch version to the rear of my lathe to directly drive the lathe head for indexing which it does with ease.

  11. #611
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    Hi,

    Sorry about this, it appears to have posted twice, Thanks Steve for your comment, much appreciated,

    Besrt regards
    Terry

  12. #612
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    Thanks Steve

    Got mine working.
    Redrew the schematic and board in eagle if anyone wants to use it.
    Click image for larger version. 

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    cad files.zip

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