Need a circuit diagram which converts millivolts to volts

Discussion in 'The Projects Forum' started by tikki, Dec 22, 2010.

  1. tikki

    tikki Thread Starter New Member

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    Hey people,

    I wanted to make an Dozzel meter. Now a days dozzel meter with ampere hour meter is easily availabl e in market.
    I wanted a circuit which converts mili volts into volts.. means... my Voltage range is in between 2v to 24v. so i want a circuit which simultaneously increase or decrese my mili volts into volts.

    If millivolts increases my volts should also need to increse.


    If anyone have some ideas about that. please tell me. its urgent.. thank you in advance
  2. blueroomelectronics

    blueroomelectronics Senior Member

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    What market? The fish market? Why is it urgent? What's a Dozzel meter?
  3. beenthere

    beenthere AAC Fanatic!

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    That's probably a "digital" meter.

    Either the meter might be rescaled, or you may need a power supply and op amp to do the scaling. What are the details about the meter?
  4. thatoneguy

    thatoneguy AAC Fanatic!

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    It sounds like you need an amplifier with a 1000 voltage gain. These can be a bit sensitive to interference. Would a gain of 100 be OK?
  5. tikki

    tikki Thread Starter New Member

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    yea.. U guyz are right. that its with amplifier and Opamps.

    Ok now let me tell you one more time.

    I want to design a circuit which will convert Milli Volts into Voltage.
    The voltage range is from 0-12V.

    Now according with the Amplifier and opamp iC's LM341 and another one its correct. But I cant make it properly. I want an circuit design for it.

    So please if anyone will help me, it will be greatfull

    thank you
  6. Kermit2

    Kermit2 Well-Known Member

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    Can you show us the circuit you have that created so far? Have you created a schematic, or built it on a breadboard? Can you draw up your idea with a circuit prototyping software pkg?

    Sketch something up in MSpaint?

    Since there already seems to be a language barrier/understanding issue, pictures would be superior.
  7. tikki

    tikki Thread Starter New Member

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    I am sorry sir, I dont have anything to show.

    I just wanted to design a circuit which converts my mV into V. Which means with increasing of mV I want that my voltage should also increase...and vice versa while decreasing.

    With the help of Amplifier and Opamp such as LM series we can build it. But As I m fresher electronics engineer I am unable to design it.
    So I want someone, who will help me to give an circuit diagram of the same.
    I hope you all got my questions and querry properly
  8. thatoneguy

    thatoneguy AAC Fanatic!

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    Do you already have a circuit that produces millivolts? Is it floating ground/isolated?
  9. tikki

    tikki Thread Starter New Member

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    Yes... I have a circuit which producing milli volts...

    Only the thing is.. I want a circuit design which connects this millivolts and voltage...


    so the circuit may be like..
    Mili volts as input then Amplifier then Op-amp(LM342 and all) and then Output as a voltage.

    So whenever i increase my millivolts.. my voltage should also increses accordingly.
  10. SgtWookie

    SgtWookie Expert

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    Last edited: Dec 24, 2010
  11. bassplayer142

    bassplayer142 Active Member

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    Look into non inverting type opamps. If you really do need a massive voltage gain of like 1000 then this may not be the best way as due to noise as another poster mentioned.
  12. SgtWookie

    SgtWookie Expert

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    Commonly available operational amplifiers can be wired as inverting or noninverting amplifiers.

    Noise is one problem, bandwidth limitations are another - a third is input offset.

    One would be better off to chain a pair of opamps with a gain of ~31.62 per stage than a single opamp with a gain of 1000 - and in this particular case, it would not matter if they were wired as inverting or noninverting.
    tikki likes this.
  13. tikki

    tikki Thread Starter New Member

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    @Wookie..

    Yea. That only LM342.... or 324. I am not very much sure about it.

    By the way Wookie.. I red your previous posts in which you mentioned some Linear technology IC's that is LT1007.
    So will that circuit will work for me. Actually i wanted to build or design a circuit in which i can convert my obtained millivolts into proper voltage.. which means... according with my mV .. i want my Voltage should also change.

    WHen i increase mV.. I want my voltage should also increase and vice versa. so do you have any circuits with which it is possible?
  14. SgtWookie

    SgtWookie Expert

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    Tikki,
    Did you look at the link I posted in reply #10?
    It shows you how to calculate the values for various configurations.

    Try to keep resistor values from around roughly 5k to 300k; lower than 5k you start loading the outputs too much; higher than ~300k or so and noise becomes a problem.

    You need to find an opamp that has very low input offset, because the input offset will be amplified in the output.
  15. tikki

    tikki Thread Starter New Member

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    Yes,.. I saw that.. Voltage divider.. but as per my knowledge it stands fr voltage only.

    According to noninverting voltage divider rule we can get double of input...
    But can u tell me that how that will help in my circuit. Because i just want to varry my output voltage accordingly with my MilliVolt Input...
  16. thatoneguy

    thatoneguy AAC Fanatic!

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    Is the millivolt input isolated and floating, or tapped off another circuit where it is referenced to a different ground? e.g. 1000:1 transformer, or voltage measured across a random resistor in a circuit?

    I asked this above and haven't gotten a response, though it is a bit important to know.
  17. tikki

    tikki Thread Starter New Member

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    @thatoneguy

    I am extremly sorry for late reply, Actually i was out of town for several days.

    The input milivolt is tapped of another circuit. we are going to get it at a random resistor of a circuit which produces DC 10V 10Amp. froim there we are going to get this mili volt. and according to that I have to make a circuit whichi will converts my these millivolts into Voltage.. which means as i'll increase my millivolts i want my voltage should also get increased.. the voltage ranger will be in between 2v to 12v
  18. thatoneguy

    thatoneguy AAC Fanatic!

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    Is the resistor in the path of the 10A current, so this will result in a current meter?

    You will need to use a differential input setup on the op amp since you are measuring across a resistor and the voltage won't have a reference ground.

    If you search for "Ammeter Circuits", you will find a lot of ways this can be done. If an ammeter isn't your final goal, the "front ends" of a few circuits shown do what you want done.
  19. atferrari

    atferrari AAC Fanatic!

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    Is that true? Something smells unreal here.
  20. tikki

    tikki Thread Starter New Member

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    Yup its true.. I just passed out my B.E. in sept 2010.
    About the knowledge so infront of this forum members.. i am feeling like zero. Not getting anything.. bigg posts and everything.... half of the things are Bouncer... And half things which I am getting I am Trying to IMplement it...
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