Electrical & magnetic field detectors

Discussion in 'The Projects Forum' started by johnsy, Jul 16, 2014.

  1. johnsy

    Thread Starter New Member

    Jul 3, 2014
    28
    0
    Hi,

    i tested a voltage detection circuit but while it works i would like to increase the sensitivity.

    I tried both bc547 and bc517.

    I did try to replace the led with a basic lm386 circuit and a small speaker.


    [​IMG]


    Concerning the magnetic field detector, i'm looking for a very very sensitive detector (natural magnetic fields)


    Thanks in advance for your help!


    Johnsy.
     
  2. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Here is a voltage detector.
    Magnetic field detector is a different circuit.
    [​IMG]


    [​IMG]
     
  3. johnsy

    Thread Starter New Member

    Jul 3, 2014
    28
    0
    inwo,

    thanks but i already tried the "electronic electroscope" (mpf-102) described on the amasci website.

    But it is not sensitive enough.

    I found a schematic for a simple "homemade tri-field meter"

    [​IMG]


    But this also have to be close or have contact (in this case a pickup coil).


    I've seen videos of hall effect sensor circuits, but you need to be really (too) close to the source.
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    maybe a flux gate magnetometer would work better.
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,974
    744
    Have you tried different values or resistance for the 1M resistor, ideally lower.
     
  6. johnsy

    Thread Starter New Member

    Jul 3, 2014
    28
    0
    That's an idea but remember that it is for outdoor work, the fgm might work better indoor.


    Most devices i found are "permanent analysis tools for measurement of the earth magnetic field" which is not what i'm after.

    looking at the tri-field earth magnetometer it's said to have a resolution of 1nT, which might work (with a probe).


    No, what do you suggest? i mostly tried various antennas replacing the copper strip.

    The pickup coil gave good results but (obviously) not really practical outside.





     
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    checkout the circuits at techlib.com
    http://www.techlib.com/
    they have some ion detectors that work for detecting electric fields. and info on building extremely high input imedance ones.
     
    johnsy likes this.
  8. johnsy

    Thread Starter New Member

    Jul 3, 2014
    28
    0
    I didn't know that site, thanks a lot!

    I guess that you mean the "spherics detector"?

    I'll definitely look into that.


    Thanks again alfacliff.
     
  9. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    actually ion detectors for deteting low level radioactivity, make good electric field detectors too.
     
  10. johnsy

    Thread Starter New Member

    Jul 3, 2014
    28
    0
    Yes, i just found that page!
     
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