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ACS712 hall sensor

andres

Oct 27, 2015
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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?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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The naive answer is a peak detector. This may go into far more detail than you need (peak detectors are at the end)
 

andres

Oct 27, 2015
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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?
 

GPG

Sep 18, 2015
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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
1.png
 
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andres

Oct 27, 2015
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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?
 

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GPG

Sep 18, 2015
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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.
 
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