+ Post New Thread
Results 1 to 7 of 7
  1. #1
    Advanced Member level 5
    Points: 16,954, Level: 31
    Achievements:
    7 years registered
    neazoi's Avatar
    Join Date
    Jan 2008
    Location
    Greece
    Posts
    3,423
    Helped
    13 / 13
    Points
    16,954
    Level
    31

    0-100uA analogue meter (needle) to show 0-10v

    Hi I have a 0-100uA analogue meter (needle) that has a marked scale of 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 and subdivisions between these.
    I want to be able to measure voltage of 0-10v with it, but the marked points to represent the actual voltages.
    In other words, the point 10 to represent 1v, the point 50 to represent 5v, the point 90 to represent 9v etc.

    Is that possible to do it and how?

    I do not mind the loading of the source, as it will be a 4A capable PSU, so I won't see any voltage drop by the loading from the meter.
    Professional engineering is the top, but amateur engineering is more fun.
    It is when you cross the barrier between these two, that things become really fascinating!

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 263,643, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    46,000
    Helped
    13989 / 13989
    Points
    263,643
    Level
    100

    Re: 0-100uA analogue meter (needle) to show 0-10v

    Already heard about ohms law? Use a series resistor. 10V/100ľA = 100 kOhm.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 5
    Points: 16,954, Level: 31
    Achievements:
    7 years registered
    neazoi's Avatar
    Join Date
    Jan 2008
    Location
    Greece
    Posts
    3,423
    Helped
    13 / 13
    Points
    16,954
    Level
    31

    Re: 0-100uA analogue meter (needle) to show 0-10v

    Quote Originally Posted by FvM View Post
    Already heard about ohms law? Use a series resistor. 10V/100ľA = 100 kOhm.
    The thing I wanted to point out was, will the meter respond linearly to the voltage changes?
    I.e 1v 10% needle movement, 9v 90% movement?
    Professional engineering is the top, but amateur engineering is more fun.
    It is when you cross the barrier between these two, that things become really fascinating!



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 80,117, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,261
    Helped
    3686 / 3686
    Points
    80,117
    Level
    69

    Re: 0-100uA analogue meter (needle) to show 0-10v

    Hi,

    according ohm´s law. 5V input will give 50uA, this is half of 100uA.
    So this should be linear.

    Nobody can tell whether your meter works linearely or not. How? You don´t give any informations about your meter.
    Also you don´t give any informations about your input. Is it pure DC, AC, waveform....?
    With non_DC input: Do you expect RMS reading (moving iron) or average (moving coil) reading?

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


    1 members found this post helpful.

  5. #5
    Advanced Member level 5
    Points: 16,954, Level: 31
    Achievements:
    7 years registered
    neazoi's Avatar
    Join Date
    Jan 2008
    Location
    Greece
    Posts
    3,423
    Helped
    13 / 13
    Points
    16,954
    Level
    31

    Re: 0-100uA analogue meter (needle) to show 0-10v

    It's pure DC. Very well regulated and cleaned from ripple. The meter is an vintage one, but one of these big ones. I have no information other than it seems well engineered, not cheap Asian.
    Ok so it is linear fair enough. Thanks!
    Professional engineering is the top, but amateur engineering is more fun.
    It is when you cross the barrier between these two, that things become really fascinating!



    •   AltAdvertisement

        
       

  6. #6
    Advanced Member level 4
    Points: 7,656, Level: 20
    Achievements:
    7 years registered

    Join Date
    Jul 2010
    Location
    Sweden
    Posts
    1,026
    Helped
    389 / 389
    Points
    7,656
    Level
    20

    Re: 0-100uA analogue meter (needle) to show 0-10v

    The series resistor should be less than 100k.
    You must subtract the meter's internal resistance from the theoretical 100k value (10V/100uA).
    In other words, the series resistor and the meter in series must have a total resistance of 100k.
    You can measure the meter's internal resistance with a normal multimeter.



  7. #7
    Advanced Member level 5
    Points: 16,954, Level: 31
    Achievements:
    7 years registered
    neazoi's Avatar
    Join Date
    Jan 2008
    Location
    Greece
    Posts
    3,423
    Helped
    13 / 13
    Points
    16,954
    Level
    31

    Re: 0-100uA analogue meter (needle) to show 0-10v

    Quote Originally Posted by std_match View Post
    The series resistor should be less than 100k.
    You must subtract the meter's internal resistance from the theoretical 100k value (10V/100uA).
    In other words, the series resistor and the meter in series must have a total resistance of 100k.
    You can measure the meter's internal resistance with a normal multimeter.
    I will put a series set trimmer after the smaller series resistor you suggest, so I can set the meter precisely at 100uA reading when 10v is applied to it.
    Professional engineering is the top, but amateur engineering is more fun.
    It is when you cross the barrier between these two, that things become really fascinating!



--[[ ]]--