I have a relay connected to pin 4 of a raspberry pi, maybe like this one https://www.amazon.com/Kyoto-Electric-KF0602D-Solid-State/dp/B00B888WVC ? Relays are a very basic electric component that most electrical people would know about. They let you turn things on and off with a microchip.

On the relay I have a noise generator. It just outputs noise when powered. I drive the pin with a 40hz square wave, using a gnuradio block.

By setting the time raster block's column number to the period of the square wave I can visualise it. This is something I've tried to do for years and only just managed to do! The visualisation helps stabilise work when issues happen, letting you see what is going on under the hood.

One next step for visualisation for me right now is to make an accumulation block that combines many signals into one: decimating them in the packet domain. But right now my system ran out of space for some reason building gnuradio. How did I build it before if cleaning and rebuilding it exhausts space?