This Raspberry Pi Oscilloscope Is Great for Guitar Visualizations

Sounds are just waves moving through a physical medium — usually air for humans like us. Because they’re just waves, they can be easily translated into electrical signals and radio waves. A typical electric guitar has electromagnetic pickups that produce an electrical signal in response to the vibration of the guitar’s strings. That electrical signal can be visualized like any other signal using an oscilloscope, and that visualization will mirror the soundwaves that you’d hear coming from the guitar itself. Jeremy Cook recently built a Raspberry Pi oscilloscope, and it turns out that it is perfect for producing projected visualizations during guitar performances.

An oscilloscope is an instrument generally used in electrical engineering, and its primary purpose is to measure electrical signals and graph them. Signals are generally plotted in two dimensions, with the X axis being time and the Y axis being the signal’s voltage. In the signal produced by an electric guitar, the voltage is the amplitude of the soundwave and the frequency corresponds to the pitch. Therefore, feeding an electric guitar signal into an oscilloscope will produce a visualization of the soundwaves being played. That can be done with any oscilloscope, but Cook's Raspberry Pi oscilloscope has the added benefit of an HDMI output that can be connected to a projector in order create a fantastic backdrop for live music shows.

In the past, all oscilloscopes were built around analog cathode-ray tubes, but today digital oscilloscopes are far more common and offer many handy improvements. Cook's digital oscilloscope was made with a Raspberry Pi 4, a Digilent Analog Discovery 2, and an old monitor. The Analog Discovery 2 is a USB device that accepts electrical signals, contains some hardware to analyze them, and passes the data to a connected computer. All Cook had to do was attach the probes, connect the USB cable, and power it up. He designed a mount in Autodesk Fusion 360 CAD software, and then cut it out on a CNC router. That mount attaches to the back of an old LCD monitor so all of the hardware is tucked away out of sight. When he wants to use the oscilloscope with a projector, he can just unplug the HDMI cable from the monitor and plug it into the projector!