Step 5. Overlap both coils as shown. Connect the motor and place the earphone in your ear. Confirm that you can hear a tone in the earphone that corresponds to the motor’s noise.
Step 6. Move one coil away from the other until the noise stops and then starts again. Find the overlap place where there is the least noise. This is called the “null.”
It may not be totally silent, but it should be diminished from what you originally heard.
Did you find the null? Please Report: firstname.lastname@example.org