Hello my friends. I am in the middle of a toy boat project. I am trying to calculate the back EMF of the BLDC motor. I made a nice picture of the circuit here below.

I want to see how much the back EMF is?

I have the OScope on the circuit and my O-Scope is telling me that the back EMF is about 60% of the source voltage. Is this making sense to you?

1) Can you tell me how I can use a pencil and paper and find out the back EMF of this motor? ( I have a print out of the motor data sheet )
2) Can you tell me how I can use the O-Scope and find the back EMF of this motor?


( I read other google sites but nobody gives me a clear answer and procedure for this problem )
Thank u
Fawaz

This is how my test circuit is wired on my table right now.

 

You might find these videos helpful:

It is not as straightforward as you might think, and it is dynamic.