How to Measure Current With an Oscilloscope


How to Measure Current With an Oscilloscope

Oscilloscopes are a fantastic tool for testing circuits. They display a visual representation of voltage versus time for signals with frequencies up to several gigahertz, and can be much more informative than just a set of changing numbers on a multimeter. While most people are aware of how to use a scope to measure voltage, many don’t realize that it can also be used to measure current. In this article, we will discuss two very simple ways to do just that.

How to measure current with oscilloscope typical has a ‘beam’ that is swept across the screen, earlier on CRT’s and today on LCD screens, by a voltage generated by the instrument. This sweep produces a plot of the voltage over time, and the instrument can be set to trigger only when a certain point in the signal is seen. This is usually referred to as edge triggering, although there are many other types of triggering available.

Beyond the Basics: Advanced Techniques with Digital Oscilloscopes

When measuring current, the most obvious method is to simply divide the voltage reading by the resistance of your probes using Ohm’s Law. Unfortunately, this only works if the current can flow to ground. If the current can’t flow to ground (for example, if you are measuring a current in a coil pickup), a differential measurement must be made – this can either be done by measuring across the resistors that the current flows through with a differential probe, or if your scope supports it, by looking at the voltage drop across a current sense amplifier built into the scope.

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