Another electromagnetic marvel to try out

This showed up in my LinkedIn feed today.

So after watching the video, I have ordered the dev kit with the knob and a couple sensor boards. Price seemed in line with what I would have expected.

Anyone else seen or worked with these devices? Wondering if it will possibly be easier or at least cheaper than an optical encoder for motor control or other uses.


  • Yes, Some time ago I built a weather station and needed to determine what direction the wind was blowing so I used a product from AMS.


    Weather Station Project.

  • You can also repurpose a Parallax servo 360 to function as a free-turning absolute encoder:

  • Nice way to re-purpose a dead part. Though at $27 vs $10 for a devboard with the chip mounted, depends on what it costs to get the magnet and mount the parts to use them for motor or similar control. Then again, given the development version of a knob to replace opticals or pots was pricey at $50.00. Depending on the value of your time, Phils fix may be cheaper.
  • As iseries suggests, Austria Microsystems (under a new name now) makes a variety of magnetic encoders.
    Here are some PCBs I made for their AS5055 chips.
    The AS5055 chips don't have the same features as the MagAlpha sensors.
    Those $10 development boards sure look like a good deal.

    In case anyone is interested, here's a link to the thread about the software for these chips. Here's a link to discussion about some of the PCBs I made for the AS5055 sensor.

    I should really mount a magnet to a stepper motor and compare the output from the sensor with the rotation of the magnet. I think the sensor does a pretty good job but I kind of doubt it would match the performance shown in the MagAlpha demo.

    Many radio control transmitters now use Hall Effect sensors on their gimbals. I was curious about the sensor inside my FrSky Taranis Q X7S so I took a photo of the sensor. I've attached a photo of the sensor. I haven't been able to find the part to purchase. The sensor in the transmitter ouputs an analog value similar to a potentiometer. The AS5055 sensor is read using SPI.

    The magnets used in the transmitter are oriented differently than the magnet used with the AS5055 sensor. Pairing an appropriate magnet with whichever sensor is used is usually pretty important in order to get good results.

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  • @Duane Degn Just ordered the MA302 boards (long and round). The boards looked like a good deal for sure. DigiKey has the chip in 1+ qty for about $7.60 and drops by about half for 500+ orders. MPS has a recommended magnet list, so that is next. The knob simulator has the MA850. Much cheaper chip (rated ~200rpm vs 60kRPM for the MA302 part), but looks like most distributors sell them in minimum 500+ orders. About $1.80 smallest order qty. So devboard seems best way to get hold of these for the moment.

    I would imagine the gimbal used for throttle on an RC controller would have to have a chip that could track linear position or one of these characterized to react as though linear. The dev kit seems to have the ability to do this looking at the demo video.

    Well, lots more fun to be had. Eventually this stuff may make it into a (maybe ATmaker) project. We shall see. Still have minimal time to do this stuff as much anymore.

  • frank freedmanfrank freedman Posts: 1,632
    edited 2020-01-21 - 06:04:15
    Some one has on heck of a great shipping deal worked out, shipping 3 day was $5.00. The box from China arrived this morning with the following contents. The pieces are shown in the boxes they came in and all in a single cardboard box.

    Not too impressed with the knob demo. Seems that for $50.00, the knob assembly could have been a bit better done than it was. Oh well, it's playtime......

    edit to add:

    Inserted the EVMA connector board into the main board. Had quite the pucker factor. The connectors are fairly fine, not the full length of the socket and while the socket is slotted for a key, the connectors on the EVMA board do NOT have a key to assist line up. Took a few very careful starts before I applied the final press on them. Not my favorite connectors; one miss and DOA.

    Ran the knob demo. worked quite well, no issues. Knob is a bit sloppy as noted and it shows up in the demo. Now to dig up the old erector set parts if they still exist in the house. Failing that, there is always the used LEGO store up the street.
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  • ercoerco Posts: 19,717
    WOW. Just seeing this. Amazing encoder speed!
  • Tried out the knob so far, for 50 bucks I would have expected a much better fit and feel than actual. When I have some time I will probably try out the motor driver on an old HDD motor. Just have to order some magnets.
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