+ Post New Thread
Page 4 of 4 FirstFirst ... 2 3 4
Results 61 to 69 of 69
  1. #61
    Advanced Member level 5
    Points: 54,221, Level: 56
    Achievements:
    7 years registered
    Audioguru's Avatar
    Join Date
    Jan 2008
    Location
    Toronto area of Canada
    Posts
    8,839
    Helped
    2072 / 2072
    Points
    54,221
    Level
    56

    Re: how to boost microvolts to higher voltages?

    Your input and feedback resistor values are very low and your voltage divider resistor values are very high and are not matched. Then your circuit does not work properly like a circuit that has a plus and minus power supply or batteries or one with an opamp to produce a very low impedance for the voltage divider.



  2. #62
    Full Member level 1
    Points: 504, Level: 4

    Join Date
    Feb 2020
    Posts
    114
    Helped
    0 / 0
    Points
    504
    Level
    4

    Re: how to boost microvolts to higher voltages?

    so the iput resistor and feedback resistor should be higher? why?



  3. #63
    Advanced Member level 5
    Points: 54,221, Level: 56
    Achievements:
    7 years registered
    Audioguru's Avatar
    Join Date
    Jan 2008
    Location
    Toronto area of Canada
    Posts
    8,839
    Helped
    2072 / 2072
    Points
    54,221
    Level
    56

    Re: how to boost microvolts to higher voltages?

    Quote Originally Posted by dl09 View Post
    so the iput resistor and feedback resistor should be higher? why?
    Because they are loading the opamp which affects the voltage divider voltage.
    But the NJM4558 dual opamp is too old to have a high resistance for the input and feedback resistors, and the impedance of your voltage divider is much too high without using two batteries or using a buffer for the voltage divider.



  4. #64
    Full Member level 1
    Points: 504, Level: 4

    Join Date
    Feb 2020
    Posts
    114
    Helped
    0 / 0
    Points
    504
    Level
    4

    Re: how to boost microvolts to higher voltages?

    so this inverting amplifier will work if i use a buffer?



    •   AltAdvertisement

        
       

  5. #65
    Super Moderator
    Points: 81,845, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,618
    Helped
    3762 / 3762
    Points
    81,845
    Level
    69

    Re: how to boost microvolts to higher voltages?

    Hi,

    so this inverting amplifier will work if i use a buffer?
    Yes, with tye suitable combination of Opamp and buffer.

    But I call it stupid ... to add a buffer instead of using meaningful resistor values.
    An additional buffer may add stability problems.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  6. #66
    Full Member level 1
    Points: 504, Level: 4

    Join Date
    Feb 2020
    Posts
    114
    Helped
    0 / 0
    Points
    504
    Level
    4

    Re: how to boost microvolts to higher voltages?

    so how do i use meaningful resistor values?



  7. #67
    Super Moderator
    Points: 81,845, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,618
    Helped
    3762 / 3762
    Points
    81,845
    Level
    69

    Re: how to boost microvolts to higher voltages?

    Hi,

    so how do i use meaningful resistor values?
    It depends on a lot of things.
    Power supply, power requirements, noise expectations, the chosen Opamp....

    Often the datasheet and application notes gives hints.
    For a more detailed selection there are dedicated application notes for each topic you want to focus on.

    Often 10k is a good start, maybe a couple of 100uA...

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  8. #68
    Full Member level 1
    Points: 504, Level: 4

    Join Date
    Feb 2020
    Posts
    114
    Helped
    0 / 0
    Points
    504
    Level
    4

    Re: how to boost microvolts to higher voltages?

    can you post links to the dedicated application notes for each topic you want to focus on?



    •   AltAdvertisement

        
       

  9. #69
    Super Moderator
    Points: 81,845, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,618
    Helped
    3762 / 3762
    Points
    81,845
    Level
    69

    Re: how to boost microvolts to higher voltages?

    Hi,

    Every Opamp manufacturer provides such documents.
    Start with the datasheet of the selected Opamp. Go to the manufacturer of the Opamp.. to the site of the selected Opamp. Usually there is a section, called "related documents", "technical documents", "application notes", "design notes" ... or similar.

    And there are more informations in the internet. Please do an internet search on your own.
    Don't let us fo the whole job for you.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



--[[ ]]--