Can you identify class of this part?

[bluerobin]

Hello to you all,

Attached is the photo of Coghlan's Big Screen Digital Compass. I am trying to identify the class of two green parts (circled). I've looked at the board and these two are the best candidates for the magnetic field detectors due to their north/south and east/west alignment. I would suspect these are hall effect linear field sensors, but all parts i can find on digikey have 3 contacts not two. The other alternative is the reed switch which matches in shape but not quite in functionality.

Anyone has an idea?

[JohnS_AZ]

Damn I'm good.   

PNI Corporation's Magneto-Inductive (MI) magnetic sensors are based on patented technology that delivers breakthrough, cost-effective magnetic field sensing performance. These sensors change inductance by 100% over their field measurement range. This variable inductance property is used in a patented temperature and noise stabilized oscillator/counter circuit to detect field variations. The Sensor Driver ASIC is the recommended implementation of this patented circuit, and can be used with the SEN-L to construct a magnetometer with up to 3-axes.

Toward the bottom of the following web page you'll see the part and links to the datasheet and ap-notes.

http://www.willow.co.uk/html/oem_compass.html

[Time]

Damn I'm good.   

PNI Corporation's Magneto-Inductive (MI) magnetic sensors are based on patented technology that delivers breakthrough, cost-effective magnetic field sensing performance. These sensors change inductance by 100% over their field measurement range. This variable inductance property is used in a patented temperature and noise stabilized oscillator/counter circuit to detect field variations. The Sensor Driver ASIC is the recommended implementation of this patented circuit, and can be used with the SEN-L to construct a magnetometer with up to 3-axes.

Toward the bottom of the following web page you'll see the part and links to the datasheet and ap-notes.

http://www.willow.co.uk/html/oem_compass.html

lol nice

[bluerobin]

great, thank you very much!

Too bad i can't find it on any of my regular distributors (digikey, etc). I bet it would be a much cheaper solution than the $20 HMC5843. The whole digital compass was selling for $18 on amazon.

[JohnS_AZ]

I doubt it would actually be cheaper.

You'd need two or three of the sensors, and their ASIC to drive them all.

IMHO, $20 for the HMC part is really quite a bargain, considering it's a 3-axis magnetometer with a pretty simple interface. The Coghlan is only two axis, which is why you have to hold it flat and level to get an accurate reading.

[Mechatrommer]

right inside my brain. to build an electronics compass! 3-Axis is a plus. where to get this?

"These sensors change inductance by 100%"
what does this mean? maximum Henry when heading south or north and 0H when heading west,east? or...
maximum Henry when heading north and 0H when heading south, in between when heading west,east?

[JohnS_AZ]

Google "3-axis magnetometer"   

[Mechatrommer]

found in sparkfun. why they spec its resolution as uT unit? cant it be just plain degree? $60? quite a price

some variation i found:
HMC6352
Digital 6 in 1 Compass
2 Axis Magnetometer with UART & i2c

i just found out that i bought the 3rd from sureelectronics a time ago, but never put it into use. not sure how good it is esp when in tilted position.

[marianoapp]

why they spec its resolution as uT unit? cant it be just plain degree?

because it's a magnetometer, not a compass, so it must measure using a magnetic field strength unit, like the Tesla