So I took some screenshots from the oscilloscope.
In photos from 1 to 3 I sourched a square wave signal of 16kHz frequency, 50% duty.
The resulting induced signal is the blue one, It have half the amplitude of the sourched one and some ripple on its "peak".
The ripple is what grow mostly in amplitude when I apply torque to the sensor, with some force is possible to see about 100mv or more than the neutral state.
In photos from 4 to 5 I am probing the original control board.
As you see it is a different situation: the sourched signal is of a strange shape, I am not sure if it has a distortion of some sort or it have such shape for a good reason.
The induced signal, the yellow one this time, has a very small amplitude when no torque is applied and is distorted... Instead, when you apply torque the signal grow greatly in amplitude and it became a sine wave, I saw more than +300mv with some force.
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In one of the last post was said that this kind of sensor doesn't give the same reading if the same force is applied on the left or right pedal.
This is true with some brands but this sensor has the ferromagnetic ring independent from the pedal axel because it is coupled the chain sprocket... So it behave in the same way for left or right pedal.
Also I don't see a different reading from the sensor when the axle rotate, maybe because this sensor measure the strain on the metal of the ring and not a magnetic field? I don't know.... And I am not sure because I cannot find specific information on the web.
The motor is a Panasonic mid drive motor of an old flyer e-bike.
I have a strong passion for motor control and did some nice and fun project in the past with a powerful 600mhz NXP MCU, yes I needed such a fast CPU for true real time response of the system.
Now I was keen to make a custom motor controller for e-bikes so I am using this bike as a platform to study the technology and it's application.
Actually I take very seriously this involvement and it is not really a game for me, so I am investing some money in instrumentation.
I hope to find here some help to understand and implement in the more efficient way this kind of sensors.
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Thank you again