Hi all,

I saw a teardown webpage/video by Adafruit on the Myo armband and I was curious about the signal acquisition hardware. I managed to find one cheaply on Craigslist and it turns out the circuit is pretty much what you'd expect.

Some of the values are a bit suspect because it was difficult to probe without a microscope and I missed a cap value or two. Also, not sure what op amp IC this is, but its layout followed a typical quad op amp package.

Unfortunately, the sampling rate is quite low (200 Hz per channel, 8 pairs of electrodes) for capturing the majority of the frequency spectrum of electrical muscle activity. I like the form of the unit and hope to tinker with it a bit more. I'd love to be able to increase the sampling rate, but I'd have to modify the hardware filtering and dig into the firmware, which seems too daunting.

Anyway, thought people might be interested.

See attached for my try at its schematic.

Here is the original Adafruit teardown (with high-res images and video):
https://learn.adafruit.com/myo-armband-teardown/inside-myo

 

Very nice! Thank you. I will try this and improve it