These types of probes can solve problems such as circuit loading or perform tests on signals, sending the results to the oscilloscope. Active probes require a power source for their operation. Using Current Probes Current probes enable you to directly observe and measure current waveforms. They are available for measuring both AC and DC current. Current probes use jaws that clip around the wire carrying the current.
Probes come with an alligator-clip attachment for grounding the probe to the circuit under test.
In practice, you clip the grounding clip to a known ground in the circuit, such as the metal chassis of a stereo you are repairing, and touch the probe tip to a test point in the circuit. You should get into the habit of compensating the probe every time you set up your oscilloscope. A poorly adjusted probe can make your measurements less accurate. Figure 27 shows what happens to measured waveforms when using a probe not properly compensated. Most oscilloscopes have a square wave reference signal available at a terminal on the front panel used to compensate the probe.