converting (0v to 5v) to (-1v to 1v)

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aashish
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converting (0v to 5v) to (-1v to 1v)

Post by aashish »

I have a current sensor which gives 0 to 5 volt output. I want to convert it to -1 to 1 v. I have a 230 V AC line supply.
Presntly I am using a adder and amplifier for the conversion using opamp. But opamp require both positive and negative supply. I cant use transformer as it make the the circuit big which i dont want.<p>I got a circuit for conversion of 230v AC to +5 V. But i had problem in converting it to -5V.<p>Please give me suggestion how can i convert 0 to 5 v to -1 to 1v.<p>Thank You
Ashish Kumar Agarwal<p>[ May 24, 2004: Message edited by: ashish ]</p>
cato
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Re: converting (0v to 5v) to (-1v to 1v)

Post by cato »

You are looking for a voltage inverter circuit. I suggest doing a google search on that term. <p>Here are the first two I came across:<p>
http://www.national.com/pf/LM/LM2687.html<p>http://www.maxim-ic.com/appnotes.cfm/ap ... umber/1875
k7elp60
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Re: converting (0v to 5v) to (-1v to 1v)

Post by k7elp60 »

This is my solution to your problem. The first OP Amp inverts the voltage and
divides it by 2.5. The second OP Amp inverts the voltage and adds the -1V offset.
Adjust the pot for -1V output when the input is 0V. The schematic is at the following link:<p>
www.poptronics.com/forums/electronic_be ... /1136.html<p>[ May 25, 2004: Message edited by: k7elp60 ]</p>
cato
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Re: converting (0v to 5v) to (-1v to 1v)

Post by cato »

K7 -
Your circuit requires a negative supply. ashish doesn't have a negative supply. His question was about how to get a negative supply or otherwise convert his signal without a negative supply.
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Chris Smith
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Re: converting (0v to 5v) to (-1v to 1v)

Post by Chris Smith »

Center tap out of a voltage divider and this will give you a negative supply,[relative to the dividers ground] but not refrenced to the original supply ground. You must float the ground or center tap, and tab below the center for the neg supply. Every thing above the center tap is pos and below is neg.
k7elp60
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Re: converting (0v to 5v) to (-1v to 1v)

Post by k7elp60 »

Cato,
You are right. I could post a circuit of a voltage pump with the LT1054CP. Since it is a 8pin
DIP the circuit still would be small. What do you think?
bodgy
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Re: converting (0v to 5v) to (-1v to 1v)

Post by bodgy »

Another way to generate a neg supply is to use a dual Op-Amp (or another one) to create a half supply reference<p>
Colin
On a clear disk you can seek forever.
cato
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Re: converting (0v to 5v) to (-1v to 1v)

Post by cato »

Yes, 1054, thats what I was trying to remember...but I think that requires an inductor?...or am I getting my swithing devices all blended together, anyway, if it does require an inductor, that can be a pain to find and tricky for the novice to deal with....pure switch capacitor might be better.<p>73
k7elp60
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Re: converting (0v to 5v) to (-1v to 1v)

Post by k7elp60 »

No the 1054 does not require an inductor and it works from 3.5 to 15V. For a schematic see my
post on the poptronix website.
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