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Thread: Driving motors through L293D

  1. #1
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    Default Driving motors through L293D

    Hi ,

    I m building a robot for my end sem project, I m almost done with the circuit part.
    Now m facing a problem with the power supply,
    My robot was working fine with the transistorised power supply .But when I try it with the batteries using a 5 volt regulator chip (7805).It stops working .
    Even with the adaptor it doesn’t work.

    I m using L293D to drive my motors(2 in no.) ,in both direction .Normal current required by the circuit is bout 330 mA .and when it switch to reverse direction current shoots up to 560 mA .

    I had tried using 9 volt batteries, n up to 10 volt from adaptor, but no output .Could anyone suggest me a way to get rid of this problem.

  2. #2
    Administrator T-1000 rao's Avatar
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    maybe the 7805 is not sourcing enough current..

    and are you sure withh all your l293D connections?? specially the Vm and Vcc pins??

    what is the voltage specs of your motor??

    rao

  3. #3

    Default

    use separate power supply for L293D and motor

    there are two pins on L293D pin 16 u give the logic 5V supply and i think pin 8 the supply for motor

  4. #4
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    What is the current\volatge rating of your battery? 7805 can source enough current to drive your motor.....remember there is a drop to 2v across it.

  5. #5
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    Post your circuit diagram.

    If your sure your 5V is giving out what it's intended to,
    check these

    VCC1-> 5V
    VCC-2->9Volts or whatever supply you want to run your motors
    GND1,2,3,4 -> all Gnd
    Check if 1A,2A,3A,4A are receivin proper logic voltages.

    Once agian,post your circuit.

  6. #6
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    Default hii

    thank u all for ur suggestions . specially yogi , ur idea worked , i tried it wid diff power supply , now its workin .
    thank u once again ...


    but now m facin problem wid the logical part

    my circuit diagram is this (ignore the reciecver part i had rectified mistakes in it)

    my robo works quit fine when in air , but ,when i keep it on floor , it start showin weird actions . all in all dont work properly ,

    my voltage specs are - 6 (i.e. 4 - AA size batteries) volt to L293D

    n 5 volt (6v I/P to 7805 ) to rest of the ckt

    all in all 8 AA batteries m using ...

  7. #7
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    Default Re: hii

    but now m facin problem wid the logical part
    Whats the problem...if your robo can work fine in air??

    my robo works quit fine when in air , but ,when i keep it on floor , it start showin weird actions . all in all dont work properly
    Probably...your motor can't drive that much of load!!

    n 5 volt (6v I/P to 7805 ) to rest of the ckt
    Did you read what I said above...for 7805 to provide voltage regulation....input should be atleast 2volt high...i.e.7volts(atleast)

    And regarding your emitter circuit.....there is no need to put those redundant AND and 2N2222,as it can be made to work it.

  8. #8
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    hii,

    i got da solution of my , problem , actually a wire wasn't soldered properly , so when in air it woks a it was in contact , but at floor because of pressure it deteches n stops workin ,

    thanks neways

  9. #9
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    Default hii

    hii there ,

    after solvin previous problems , now m facin a new problem , n not able to fix it :cry: ,

    actully , whts happinin is , my bot takes jerks ,while moving . i mean its logic is wokin pritty fine ,n sensors too . but then also , it is not showin xpected performance .
    first i thoght it may be the things near it . but then in an open area , same problem presisit .

    i m givin 12v power supply (8 AA batteries) to it . 12v to L293D n 5 v regulated to rest of the ckt .

  10. #10
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    It would really help,if you post your L203d circuit

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