Is it realistic to use hall effect current sensor to sense down to mA ? - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: September 11, 2013, 05:25:09 am
content: While browsing Allegro various current sensor ICs, just curios if its worth the trouble to use it for sensing with the resolution down to mili Amp ?An example from one of the IC datasheet stated that the sensitivity is typical at measly around 100mV/A....or I will ended with just getting noise at that level.

author: alxnik
author_rank: Regular Contributor
timestamp: September 11, 2013, 06:51:13 am
content: Sensing ICs? Not sure.However, you can have something like this:http://www.ebay.co.uk/itm/TA17-03-Octopus-Non-invasive-AC-Current-Sensor-Brick-Module-For-Arduino-/251312633800?pt=LH_DefaultDomain_0&hash=item3a836677c8which is AC only, or:http://www.ebay.co.uk/itm/CURRENT-SENSOR-100A-AC-OR-DC-Part-CSNF661-/390614567277?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item5af271496dWhich is AC/DCThe good thing about these is that you can buy a large measurement range sensor and then you can increase sensitivity by looping the sensed wire multiple times through the sensorPersonally, I have 2 AC/DC hall effect sensors (max 45A) and by looping the wire 5 times through the sensor I get ~300mV/A. With a 10bit ADC I can get about 8-10mA accuracy. However I guess you can get more accuracy/less range with more loops

author: BravoV
author_rank: Super Contributor
timestamp: September 12, 2013, 08:10:57 am
content: alxnik, thanks though, my interest is only at IC based and those are way too big also suitable for huge current only.Quote from: mojo-chan on September 11, 2013, 08:24:06 amAre you saying this kind of chip output basically useless at that level ? Please elaborate further ?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 12, 2013, 08:33:00 am
content: Hall effect, probably not, Magnetoresistive, maybe. NVE make some nice MR sensors.But The Earth's magnetic field, and other magnetic stuff may spoil your day.

author: BravoV
author_rank: Super Contributor
timestamp: September 12, 2013, 10:01:34 am
content: Ok, thanks for the replies guys, also looking at Mike's suggestion at NVE's MR sensor especially for current, its not that interesting.I guess still the old current sense through resistance is still the easiest method.

author: ovnr
author_rank: Frequent Contributor
timestamp: September 12, 2013, 12:09:57 pm
content: If you don'tneedisolation, it's not worth it to use the hall effect sensors IMO. The Allegro parts are fairly noisy, and mA-level sensing is going to be buried in the noise.They're great when you need some rough idea of the current (and 100mA inaccuracy wouldn't cause trouble) and the isolation comes in handy.

author: Zero999
author_rank: Super Contributor
timestamp: September 12, 2013, 03:33:59 pm
content: LEM make a low current hall effect sensor.http://www.digikey.co.uk/Web%20Export/Supplier%20Content/LEM_398/PDF/lem-industrial-catalog.pdf?redirected=1One thing you could try is using multiple turns, so if your sensor gives 100mV/A, using ten turns will give 1V/A.

author: BravoV
author_rank: Super Contributor
timestamp: September 14, 2013, 08:34:27 am
content: Quote from: Hero999 on September 12, 2013, 03:33:59 pmThanks for the link, but I've decided to stop this quest, and after long thought, I guess I feel content with just using resistance to measure current now.