Hello I work as a college lecturer and trying to get students to make the most out of using our Picoscope. My question relates to ABS, we get the students to do all the basic checks using a meter. We then get them using the scope. While using the scope to check a Renault Scenic ABS sensor we struggled to get a reading.

These sensors are the Magneto type so we told the students to expect to get a digital pattern, for at least half an hour they struggled and then asked for help. It was lunch time so I had a look in peace. I also struggled to get any reading until I removed the black lead and changed the voltage from DC to AC and got a pattern.

I am struggling to explain this to the students in any real detail, I am not someone who just gets them to scope and not understand what they have done.

Can you help me to explain how I got the pattern and how changing the voltage from DC to AC made a difference, is this something to do with AC Coupling. Thanks in advance Pete.