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ACS712 hall sensor

Discussion in 'Sensors and Actuators' started by andres, Oct 27, 2015.

  1. andres

    andres

    3
    0
    Oct 27, 2015
    Hello Members, I'm new to this forum, I'm trying to get into the Raspberry Pi, Odroid type projects. Question? I'm reading "up to 30amps ac current thru a ACS712 hall sensor using, that putting a out 0-5 volt signal. My problem is peak detection, trying to regulated and put out accurately, I don't want long hold need to read current drop.

    can someone help?
     
  2. GPG

    GPG

    452
    66
    Sep 18, 2015
    AC or DC?
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,191
    2,693
    Jan 21, 2010
    The naive answer is a peak detector. This may go into far more detail than you need (peak detectors are at the end)
     
  4. andres

    andres

    3
    0
    Oct 27, 2015
    it is a ac output. yes, I talked to the manufacture they recommended a peak detector at the end of the signal. my problem is finding one that will work and simple to do. can someone help?
     
  5. GPG

    GPG

    452
    66
    Sep 18, 2015
    Positive peak sample/hold.
    If you need to reset add a transistor across the capacitor and switch on for reset to 0V
    Use jfet input or cmos amps for longer hold time [​IMG]
     
    Last edited: Oct 29, 2015
  6. andres

    andres

    3
    0
    Oct 27, 2015
    GPG thanks! But I have no Idea how to size the component to make this work. GPG will this peck detection work with a 0-5 Vin. I need a shot hold to see voltage drop or bleed voltage out?
     

    Attached Files:

  7. GPG

    GPG

    452
    66
    Sep 18, 2015
    http://www.ti.com/lit/ds/symlink/lmc6482.pdf
    Looks like a suitable amp. Will run off 5V single supply and swing close to the supply. The choice of capacitor. not electrolytic. There are MLCC caps with low leakage. C*V = I*T Insert the values and this will give you the maximum C. Use ~ 2-3mA for I. T depends on how fast you need the output to follow input. Bleed if used depends on how long you need to hold for. The alternative being no bleed and a transistor to reset under external control. The dual amplifier version has an output buffer so that the reading current does not change the value. The single version you posted uses an amplifier that qualifies for old age pension.
     
    Last edited: Oct 31, 2015
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