Oscilloscopes are an electronic test device that allows you to observe the varying signal voltages. They are used in a lot of different industries and they are used to test and watch the change to electrical systems over time. They are used by mechanics, nurses, lab technicians and engineers alike, but the oscilloscope itself can’t do much. This is why we also need probes.
Probes come in a variety of sizes and shapes and for a multitude of uses, and they come in two types–active and passive. While the oscilloscope itself is a complicated piece of equipment, there are companies out there that deal solely with the probes; they manufacture them, test them, come up with different ways to use them and deal with the many parts and even storage options for them, this is how important the probes are to the overall unit. You can’t read something if you have no way of getting the information to the device, right?
Passive probes, then, are ones that contain no active electronic parts. Therefore they require no external power to feed them. You need specific probes because ones not really there for the job at hand can lead to interference and won’t give you a proper read of the information. Scope probes use coaxial cable to transmit the signal from the tip of the probe to the oscilloscope. This cable protects the signal from any external electromagnetic interference and therefore you get a more accurate read. This type of probe also has a lower inductance than so called flying leads making them more accurate for increasing frequency signals.
Active probes, on the other hand use a high impedance, high frequency amplification mounted in the probe head itself and they also use a screened lead. These are the more expensive option however, as there is more to the manufacture of them, and they also require their own power. Their dynamic range is also limited, however, they have a low voltage rating which allows the heads to be very small. Some industries love that fact as they are more convenient to use with modern circuits than the bigger, bulkier option.
Just like a car can’t run without an engine, an oscilloscope can’t work without its probes. Which probes you need or want will depend on what you are using the device for but with so many options it should be easy to narrow it down.