Oscilloscope Probes & Why You May Want an Extra

An oscilloscope probe is a versatile measuring tool.  Some of you might wonder, why would someone want a third oscilloscope probe for a 2-channel oscilloscope?  On the other hand, some of you technically savvy electrical engineers out there might already know the answer.

In case you want one good example on how you might our Tech Support Guru George Leger gives a short talk in the video below.  He details how he uses a third oscilloscope probe to assist him in the testing on one of his recent electronic projects.  In the video George uses the DSO5202P Hantek 200MHz Oscilloscope.

He had some pretty advance uses for the 3rd probe as you can see.  If you’re looking for more general information about oscilloscope probes we’ve provided a quick run-down below.

About Oscilloscope Probes

According to most sources, including Merriam Webster, an oscilloscope test probe is defined as:

A physical device used to connect to test equipment to a DUT (device under test).

Scope probes can either be active (requiring electricity to function) or passive (not containing components).  We will discuss passive oscilloscope probes here.  Oscilloscope probes test extremely high frequency signals, we’re talking hundreds of thousands or millions (!!!) of samples per second.  Because of these high frequencies a coaxial cable is used instead of flying leads, i.e. simple wires.  A coaxial cable both protects the signal from external EMI’s and has lower inductance than simple wires which enables it to measure smaller signals more accurately.

A probe that is directly connected is called a 1x probe.  Whereas a 10x probe reduced the capacitive load of the probe by 10 times, many oscilloscope probes such as our 200MHz oscilloscope probe have a slide switch so you can adjust capacitance based on the application. Approximately 100pF per meter of capacitance is generated in a typical coaxial oscilloscope probe.

Oscilloscope Probe
150MHz oscilloscope probe

Almost all oscilloscope probes will also have a grounding wire, usually quite short to reduce inductance, that you can use to ground the probe to the circuit board or DUT’s reference voltage.

To read more about oscilloscope probes check out this good article from Hackaday.

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