Unipolar driver not working?????

Discussion in 'The Projects Forum' started by crazybuoy, Mar 30, 2011.

  1. crazybuoy

    Thread Starter Active Member

    Sep 19, 2010
    62
    0
    I am using the attached unipolar driver. I think it will work by providing 1 & 0 pulses to Step point to more steps, 0 or 1 to Direction point to change direction and 1 to enable & 0 to disable for Enable point. But it works in the following way unexpectedly:

    with Step=0, Dir=0, En=0
    the motor takes some backward and forward steps itself with above situation and stops by changing En=1

    Why is it performing in the way. I want to move every step one by one. Please guide me.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    How is your circuit constructed? Have you verified all connections and components? With direction and enable levels held steady, does the 4516 count with each step input? Are all inputs always at a logic level? If any are left floating, the logic will behave unpredictably.

    You should be able to follow the logic with a meter.

    It seems odd to use a binary counter to feed a BCD to decimal decoder. The FET gates should have 100 ohm resistors in series with the logic gate drives. I would move the dioded D1 - 4 so they were across the FET's to protect against voltage spikes.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    There are no bypass capacitors shown on the 4000-series IC's, but they are required; 0.1uF capacitors connected across the Vdd and ground pins, as close as possible to the ICs.
     
  4. crazybuoy

    Thread Starter Active Member

    Sep 19, 2010
    62
    0
    Thanks, I have MC14516BCP by Motorola a binary up/down counter instead of CD4516B by Taxes Instruments. Is It cause problem due to fake MC14516BCP?
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Doubt it - Motorola is a good source for IC's.

    Can you issue one clock pulse and verify that the count has changed by 1? Does the 4028 change state accordingly?
     
  6. crazybuoy

    Thread Starter Active Member

    Sep 19, 2010
    62
    0
    I have tested the result with three power supplies: 5V 0.450A, 12V 0.250A and 24V 1.6A. With 5 & 12 V power supply, both 4516 & 4028 change the states correctly.

    But with 24V, the output of 4516 remain high for only once then it goes to low(0) forever. And only one output of 4028 remain high(1) forever and others remain low(0) forever. Why it behave in this unexpectedly with 24V supply? How to correct it by adding any more component or with any other way?
     
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