Plot a Christmas Tree on an Oscilloscope

Remember back in the good ol’ days when the family would gather around the oscilloscope to watch grandpa generate a Christmas tree on his circular-faced analog ’scope in preparation for Santa? While that may only be a figment of my imagination, if you ever wanted to bring a little Christmas cheer or other shapes to your digital or analog scope, YouTuber Electronoobs shows us how it’s done in the video below.

To generate the proper X/Y coordinates, Electronoobs turns to an Arduino Nano to output faster-than-normal PWM signals on two pins. These signals are smoothed out using a pair of resistor/capacitor filter setups, then the timing is adjusted to give the oscilloscope a clean signal. The trick, or tricks, to doing this is that the ’scope needs to be placed in X/Y plot mode, and the image needs to end exactly where it started. This is, of course, perfect for a symetric Christmas tree, and he was also able to spell out his handle in a nicely stylized font. Another restriction for this configuration is that the size must be within a shape of 254x254 vertices, corresponding to the Arduino’s analog write resolution.

While the results are quite impressive, the hack itself involves only a handful of components and careful preparatory hand-plotting. Code for the build is found on the project’s write-up if you’d like to try something similar yourself!