What is the purpose of this resistor?

[Jubbsta]

Hey guys, I’m in the process of learning how to use an oscilloscope. I was curious, what is the purpose of this resistor, and what’s the reasoning for having the probes set up like this? The diagram is for testing a wheel speed sensor. Thanks!

 

[Papabravo]

The output circuit is an open emitter (source) and the 100Ω resistor is the load. It completes the circuit and allows the oscilloscope to "see" the output signal. So, with the resistor in place the output circuit is referred to as a common collector (drain), or alternatively an emitter follower. The output device could be either a BJT or a MOSFET

 

[Jubbsta]

The output circuit is an open emitter (source) and the 100Ω resistor is the load. It completes the circuit and allows the oscilloscope to "see" the output signal. So, with the resistor in place the output circuit is referred to as a common collector (drain), or alternatively an emitter follower. The output device could be either a BJT or a MOSFET

Thank you, that makes perfect sense! I spent a good portion of the day capturing waveforms from various sensors and this was the first sensor that required it to be hooked up like that. Lots of trial and error messing around with the settings to get what i wanted