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We are working on a project. Our goal is to measure the DC current of a cable ranging to 1A-50A. However the hall meter doesn't seem to react at all when putting a cable with 2A close to it. We get a voltage difference with a strong Magnet.

How do we go on from here? How do we amplify the signal enough for us to notice it? Do we need an instrumental amplifier?

We are using Arduino UNO.

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  • 2
    \$\begingroup\$ What hall sensor? Schematic? \$\endgroup\$ – pgvoorhees Oct 10 '16 at 13:00
  • \$\begingroup\$ is there an insulation gap to sensor? \$\endgroup\$ – Sunnyskyguy EE75 Oct 10 '16 at 13:07
  • \$\begingroup\$ What do you mean by "putting a cable close to it". You should put a DC cable through the sensor. \$\endgroup\$ – Marko Gulin Oct 10 '16 at 13:17
  • \$\begingroup\$ Have a look at the method of operation of an LEM industrial current sensor here: electronics.stackexchange.com/questions/261794/…. \$\endgroup\$ – Transistor Oct 10 '16 at 17:06
  • \$\begingroup\$ 1. Right now we are just excerpimenting with a "95A 425-", didn't find anything about it anywhere but it looks like this sparkfun.com/products/9312 2. Insulation gap to sensor? 3. The point is to build something that doesn't require "through the sensor". We simply just want to "put a cable close to it". It works with the magnet, so we figured that by amplifing the Hall reading, we could get it to work with a cable???? 4. Thanks! \$\endgroup\$ – Mark N Oct 11 '16 at 7:08
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If I were you, I would use an integrated Hall Effect current sensor, something like an ACS758. It has decent linearity and full scale accuracy, and can be had in a 50A Uni- or 50A bi-directional (as well as 100A and 150A variants). Alternatively, you could use a ferrite core to concentrate the magnetic field through a linear HE sensor, like an A1363.

The reason your test didn't work is probably because either the sensor wasn't sensitive enough to pick up your magnetic field or the field lines weren't intersecting the hall plate properly.

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  • \$\begingroup\$ Okay great! We are going to buy a couple of Hall sensor when we know what to buy! Right now we just want a small difference with our current sensor, so we "know that it's possible" to do it like this! \$\endgroup\$ – Mark N Oct 11 '16 at 7:16
  • \$\begingroup\$ The unidirectional version of the ACS758 is a DC current sensor. Any wire with current flowing through it produces a magnetic field, even dc. The trick to getting a hall sensor to pick it up is to concentrate that field and/or couple it properly into the sensor. If you use an integrated sensor like the 758, the in-package current bus acts as the field concentrator. If you use something like the 1363, you need a ferrite toroid core with a split (to accommodate the sensor). The core needs to have at least one or two windings. This couples the field from the wire into the core, into the sensor. \$\endgroup\$ – Brendan Simpson Oct 11 '16 at 12:28
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Hall sensors measure magnetic field in [Tesla], which is a field that drops off in strength greatly with separation in gap distance. Thus the most reliable method is to choose Current Sensors with all the current going thru a loop in the sensor.

here are 3 methods are :

  • ferrite toroid loop with conductor thru hole (current transformer, CT)
  • clam shell loop current probe with a degaussing circuit in case of saturation.(expensive probes) but has DC response.
  • Hall sensor chip with built in linear correction using <= 1 milliohm current shunt in chip (like the ACS711)

Don't just put a Hall sensor on a wire loop near current conductor and expect to measure current. This is due to poor variable magnetic coupling.

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  • \$\begingroup\$ Why would you choose the ACS711 instead of something like the ACS758, which is an actual 50A sensor? Why would you post the whole thing if it didn't work? \$\endgroup\$ – Brendan Simpson Oct 10 '16 at 13:38
  • \$\begingroup\$ Thanks Brenden, it was just an illustrated example, the major point here is how to measure current \$\endgroup\$ – Sunnyskyguy EE75 Oct 10 '16 at 13:46
  • \$\begingroup\$ Yes we want to measure current. But we can't have a closed loop system. Something with hinges could/should work. Because we want to measure a DC wire without having to break and put the wire through our sensors. The main question: We got a reading from a magnet, shouldn't we also get a reading (probably very small) from a DC wire. We probably have to amplify it, but how? We have read about instrumental amplifiers and differential amplifiers. Do you guys have any knowledge about these? \$\endgroup\$ – Mark N Oct 11 '16 at 7:15
  • \$\begingroup\$ I have a lot experience using Tektronix current probes, sorry you cannot make this. Where are you measuring current. Use a wire of known resistance then. \$\endgroup\$ – Sunnyskyguy EE75 Oct 11 '16 at 7:59
  • \$\begingroup\$ imgur.com/a/6C4HL Red=Hall sensor, and using hinges to create a open loop system. So you just clamp it around a wire, and it outputs how much DC current it's flowing through it! Hello thank you for your response. So you're saying that this is impossible? Our goal is to make a DC current meater using Hall effect sensor. How should we do if this is impossible? \$\endgroup\$ – Mark N Oct 11 '16 at 8:46

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