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  1. #1
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    reverse the sign of the direct current

    hello
    I want to reverse the sign of the direct current
    I want to reverse +1 VDC to -1Vdc
    Help me please

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    reverse the sign of the direct current

    A little more detail would be useful e.g. do you want just a small current or several amps?

    Anyway, assuming you don't want too much current, and inverting opamp is one way.

    Keith.
    I started life with nothing and I've still got most of it left. (Seasick Steve)


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    Re: reverse the sign of the direct current

    thank you my Friend "keith1200rs"

    I have a +1VDC voltage, so from the this tension, I want the -1VDC, to change the direction of rotation of a drive speed.
    So I want to reverse the voltage from +1VDC to -1VDC



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    reverse the sign of the direct current

    If you are reversing a motor drive, can you not simply use a relay?

    What current?

    Keith
    I started life with nothing and I've still got most of it left. (Seasick Steve)



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    Re: reverse the sign of the direct current

    see my freind
    the drive speed has only 1 inbut of direction, if the value is +1VDC we have a direction, if it is -1VDC we get the second direction.
    I have 2 Potentiometers, the value of output of the first Potentiometer is OK " +1VDC "
    And I have also the value of the second Potentiometer is +1VDC, But I need it -1VDC



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    reverse the sign of the direct current

    Hi elmahboule,
    in that case you have two possibilities;
    1,
    the second potenciometer is to supply from a opposit polarity as the first one!
    2,
    if you dont have an inverted voltage for your second poti`s supplying= use a voltage inverter amplifier; BUT for that you NEEDS a SUPPLY WITH +/- voltages...
    K.


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    Re: reverse the sign of the direct current

    thank you " karesz "
    Now I understand
    I must use the am_op
    as this



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    reverse the sign of the direct current

    Quote Originally Posted by elmahboule
    thank you " karesz "
    Now I understand
    I must use the am_op
    as this
    Yes, but equal resistor values to get a gain of -1.

    Keith.
    I started life with nothing and I've still got most of it left. (Seasick Steve)


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    Re: reverse the sign of the direct current

    yes " keith1200rs "

    R1 = R2

    thank you, But I do not know the picture of integrated circuit
    So can you give me the picture of this integrated circuit. " am_op "



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    Re: reverse the sign of the direct current

    Quote Originally Posted by elmahboule
    yes " keith1200rs "

    R1 = R2

    thank you, But I do not know the picture of integrated circuit
    So can you give me the picture of this integrated circuit. " am_op "
    Hi elmahboule,

    You can use commonly available LM741 and wire it up like the picture you posted above.

    Refer to datasheet of pin description: http://www.national.com/ds/LM/LM741.pdf

    Good luck


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  11. #11
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    reverse the sign of the direct current

    It would be useful to have a bit more information - there may be an easier solution. For example if you just want +1V or -1V then an analogue switch may be all you need.

    Keith
    I started life with nothing and I've still got most of it left. (Seasick Steve)



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