I've been testing the EMG sensor below:
During my tests, I could not get any changes in the signal caused by muscle tensions. When all (3 of 3) of the electrodes where disconnected, my Arduino read 1023, the max analog value. When I had them hooked up, the Arduino read values between 30-40. One problem I encountered, was that it didn't say which of the colors (red, green and yellow) should go where. There were linked a user manual from the ebay link, but they were using different colors. Anyways, I tried all of the possible combinations, but I still got the same result; between 30-40, no remarkable changes in value.
Could it be the adjustable gain? Polarization?
If someone has any experience with EMG, or ideas about what might be the problem, please let me know.