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reverse the sign of the direct current

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elmahboule

elmahboule

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

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.
 

    elmahboule

    elmahboule

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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
 

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

What current?

Keith
 

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
 

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.
 

    elmahboule

    elmahboule

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

elmahboule said:
thank you " karesz "
Now I understand
I must use the am_op
as this
Click to expand...

Yes, but equal resistor values to get a gain of -1.

Keith.
 

    elmahboule

    elmahboule

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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 "
 

elmahboule said:
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 "
Click to expand...

Hi elmahboule,

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

Refer to datasheet of pin description: **broken link removed**

Good luck
 

    elmahboule

    elmahboule

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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
 

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