L298 driver goes crazy

Discussion in 'The Projects Forum' started by rorlich, Mar 26, 2011.

  1. rorlich

    Thread Starter New Member

    Mar 26, 2011
    Hello all
    i wanted to build a driver for my robot

    it got 4 dc motors , i used the schematic attached.

    only 2 differences -

    1. i use 4148 diode instead of schottky
    2. i use 4049 inverter.

    i'm shorting the 2 left dc motors to each other and same for the two right motors, that way one driver output is splitting into 2 wheels

    when all connected good and tripled checked + rebuild the circuit
    my wheels direction gets crazy, after few seconds of running the wheels start changing direction involuntary from back to forward and all over again..

    my pic is controlling the direction , so basicly some how the driver is shorting the pic i/o.

    + my driver is getting very hot , i use a regulated 9v output from my MicroChip Explorer16 pic (which i think is limited to 800ma)

    any ideas how to fix this ?

  2. hgmjr

    Retired Moderator

    Jan 28, 2005
    As you may know, the dual H-bridge driver used in the schematic is intended to be used to control two motors. If I understand your description of your circuit, you are using the H-bridge to drive two pairs of motors with each of the pairs made up of two motors in parallel. If I have understood your connection correctly then you may want to try connecting the H-bridge with one motor per H-bridge driver. I suspect that one of your problems is the H-bridge may be overloaded and as a result is overheating.

  3. rorlich

    Thread Starter New Member

    Mar 26, 2011
    thanks for the reply
    is is possible this is because the diodes ?