How an Oscilloscope Probe Works


An oscilloscope probe is used to connect the device under test (DUT) to an oscilloscope. It acts as a transmission line, passing your signal from the source to the oscilloscope. Understanding how an oscilloscope probe works is critical to obtaining accurate measurements with your oscilloscope.

When you connect an oscilloscope probe to the signal in your circuit and an oscilloscope, the oscilloscope probe becomes part of your circuit. And, because of this, the signal you see on screen is the signal plus the effect of the probe.
Oscilloscope probes are specifically designed to limit interference or loading in order to avoid influencing your measurement (as much as possible, that is).

The circuitry inside your probe, mainly the attenuator, is designed to counteract this interference. If you are using a passive probe, it has a rating such as 10:1 or 1:1. This means the probe has an attenuation factor of 10-to-1 or 1-to-1, respectively. Probes come in a variety of forms, with different attenuation factors, tip styles, and ground lead lengths. These and other factors will determine how much an oscilloscope probe affects the measurement you are making.
For getting started, it won’t matter too much which probe you use, but as you need higher degrees of accuracy or need to measure higher bandwidth signals, you may find yourself reaching for an active probe.

Getting Started Using an Oscilloscope Probe:

Step 1: Plug the probe into Channel 1 of your oscilloscope.

Oscilloscope Probe - 1000x with probe connected

Step 2: Attach the probe tip to the signal you want to test.


Step 3: Attach the ground tip to a known ground.



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