----- Original Message ----- From: "Yigit Turgut" To: "Microcontroller discussion list - Public." Sent: Sunday, June 06, 2010 12:14 AM Subject: Re: [EE] Measure current in a wire using hall effect sensor I have done a similar project but I had to design the whole sensor thing by myself. I designed a toroid with proper parameters and using a 16f84a I could print the current in the wire to lcd. >> Using those values I get a B field of >> [2 x ten minus 4 ] Tesla or 2 Gauss. >> >> If I did the calculations correctly, it seems >> that an Allegro A1323 linear hall effect sensor >> ( HES ) (1) should work. This part has an output of >> 2.5 mv / G. I am planning to measure a range >> of 1 amp to 200 amps. Should I make the >> HES part of a magnetic ring around the >> wire ? The ring would consist of two "C" sections >> married to each other sandwiching the HES. >> Would steel be a suitable material >> given I am measuring DC to 120 Hz ? Does the >> steel have to be laminated ? Or would a ferrite >> ring be necessary ? >you can't measure DC since it will not induce a magnetic field. Also notice >that you need to have very precise equipment in order to get accurate >results at VLF. I'm not sure about the above statement in relation to the OPs project. AFAIK: DC produces a static magnetic field proportional to the current, and I thought Hall effect sensors worked fine with static magnetic fields (not that I have ever used them though) given that the field produces a tiny potential difference across the sensor due to the Lorenz force on the carriers. It sounds as though your project measured current induced in a winding by a changing magnetic field so it could not measure DC, which is a little different to the OPs intention of using a HES. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist