Measuring current with oscilloscope with an oscilloscope offers the advantage of a more intuitive visualization of changing signals compared to the steady values displayed by a multimeter. However, because an oscilloscope is a high impedance voltage measuring instrument, it cannot directly measure currents — it must convert the current to a voltage before it can be measured. There are a couple of ways to do this.
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One method is to use a combination of a shunt resistor and differential probe. The shunt resistor provides the current measurement while the differential probe gives you the voltage reading. However, this approach is limited to around 1 mA resolution.
Another way to measure current is to use a Hall sensor probe. This is a device that converts magnetic field changes into electrical currents, and it measures both DC and AC currents. This approach is more precise than using a standard shunt resistor, but it can also be less accurate due to the fact that it does not provide true Ohm’s law measurements.
Once you have the correct current-to-voltage converter connected to your oscilloscope, set the trigger to a valid voltage value. This freezes the waveform on the screen for you to observe and analyze.
A grid on the display acts as your ruler, offering a reference point from which you can measure signal characteristics such as amplitude (how tall it is) and frequency. For more detailed analysis, many oscilloscopes have markers that can be dragged to specific points on the display to measure precise values or changes in the waveform. Some even allow you to do basic math on the waveform(s).
