Melexis is a well known and reputable Belgian semiconductor manufacturer. When they recently announced that they were bringing out a new Tri-Axis magnetic sensor in analog format with standard, through-the-hole wiring, we believed this would provide an excellent consumer oriented product. At a reasonable cost, it offered great accuracy and a very compact footprint. It was the new MLX90371GVS-BCC-100-SP-ND.
It was therefore with great excitement and anticipation that we ordered twelve of these units from Digi-Key. We changed the designs of the Gunsight Base and Range settings to incorporate the new sensor and the Elevator Trim was also designed on this principle.
And then we tested it. Solid output of 2.48V, no matter how we moved the magnet. Refer to the oscilloscope diagram in the featured image above to see it flatline. Well it took many emails and to-ing and fro-ing between Digi-Key and Melexis before we obtained an answer. The units are pre-programmed to have both the lower limit and upper limit of the analog output at 50%! This effectively makes them useless unless you also happen to own a Melexis programming and daughterboard, available at the small sum of around $2000 🙁
I am waiting for an answer from Melexis why they have programmed them in this way, effectively making them unusable for the general consumers, hobbyists and makers. And why there is no explicit statement on this in their literature. I have yet to receive an answer.
Anyway, one has to move on from these little setbacks. We have updated the designs for the Gunsight rings and Elevator Trim with mini potentiometers. For the more critical controls of roll/pitch/yaw, we will be using the Bi-Tech 6127 Rotary Hall Effect Sensors. These come pre-programmed in a selection of operating angles which is great. Many thanks to Sokol1 on the SimHQ forums for pointing this one out. It is simply a drop-in replacement for potentiometers which makes installation and link-up extremely simple.
Some images of the changes that had to be made on the Elevator Trim design:
Just as a post script to this, Digi-Key have since responded and will be offering me a full refund and I don’t need to bother sending them back. Good on you Digi-Key and thank you! I trust the website will still be updated to reflect that these units are unusable without a programmer and daughterboard.