Could someone shed some light on a working principle of this Electronic Throttle Body from MagnetiMarelli? (Found in BMW R1200GS motorcycle).

Seems to be contactless feedback via the 4 tiny pins. The two big pins go direct into the motor.

Can't measure the resistance on the tiny pins, as it floats.

Mechanical side with a motor

PCB and contacts

  • \$\begingroup\$ maybe hall effect sensor , needs supply \$\endgroup\$
    – ElectronS
    Jul 19, 2017 at 14:46
  • \$\begingroup\$ A close up photo of the circular pattern on the PCB would be helpful, so we can see what sort of pattern the tracks follow. If you can get it off and photo the otherside, that would be helpful too. \$\endgroup\$
    – Jack B
    Jul 19, 2017 at 15:09
  • \$\begingroup\$ Try clicking and zooming-in on a photo.The circle alone is 600x600 pixels. Unfortunately, I can't remove the PCB - might be placed there with precision in mind, and its a pricey thing (~$300 used). \$\endgroup\$ Jul 20, 2017 at 13:27

2 Answers 2


Looks like some form of capacitive or inductive rotary encoder to me.

Presumably some common signal is coupled into that six segment yoke through the four turn outer coil on the PCB which then couples back to the radial segments on the PCB via the spokes on the wheel.

Hard to tell if it's capacitive or inductive though without seeing what is on the other side of the board and maybe a scope trace if two, but my $1 is on capacitive.

Either way, I'd guess those four pins pass quadrature position information though the S1 and S2 pins.


Did some research on the nature of this sensor. It is inductive. The working principles defined in this thesis.

enter image description here

enter image description here

The chip itself is from HELLA (“CIPOS®” - Contactless Inductive Position Sensor) enter image description here

  • \$\begingroup\$ Good find. We recommend that you quote enough of the reference that the answer can stand on its own when the link goes dead. It also saves us opening a link. \$\endgroup\$
    – Transistor
    Jul 21, 2017 at 7:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.