This is a virtual oscilloscope — a tool engineers use to see what audio signals really look like. Pick a waveform, apply an effect, and watch the wave change in real time. Use this before coding any pedal in the Effects Pedals modules — when you can see what an effect does to a wave, building it in code becomes much less mysterious.
Generate a signal, apply an effect, see what happens.
This is a sine wave — the simplest possible sound. Every other sound in the universe is a sum of sines like this one at different frequencies. Mathematicians call this Fourier's theorem, and it's the foundation of everything you hear in the modern world.
The number of full waves you see across the screen depends on the frequency. At 440 Hz (the "A above middle C"), you're seeing 440 cycles per second — though we're only showing about 8 cycles at a time so you can see the shape clearly.
Each experiment maps to a concept you'll meet in the Effects Pedals modules. Read it, then play with the controls until you understand what's happening.
Tap each waveform button. Notice the shapes: sine is smooth, square is steps, saw is ramps, triangle is peaks. These are the four building blocks of every synthesizer ever made.
Start with a sine wave at full amplitude. Apply distortion. Slowly raise the amount. The peaks get chopped off — the wave starts to look more like a square. This is exactly what Module P3 builds in code.
Pick any waveform. Apply tremolo. The wave gets taller and shorter on a slow rhythm. The signal frequency doesn't change — just the amplitude. This is Module P5's first half.
Pick a square wave. Apply low-pass filter. Crank the amount. The sharp corners round off — the square turns into something like a sine. The filter removes the high frequencies that make corners sharp. Module P2's wah uses a related filter.
Pick a sine wave. Apply delay. You'll see a "ghost" of the wave riding alongside the original, slightly shifted. With feedback turned up, multiple echoes stack. This is the heart of Module P4.
Ring modulation multiplies the signal by a sine at a different frequency. The result is bell-like and otherworldly — think the Daleks from Doctor Who, or the early Theremin records. The same math turns into FM synthesis at higher rates.
This in-browser oscilloscope is great for visualizing what effects do mathematically. To see your actual Piper running real audio in real time, run the Python oscilloscope script on the kit:
python3 mic_scope.py
The Python version reads from the USB microphone and draws the real waveform from the room — speech, music, ambient noise. Pair it with any Effects Pedals module to see your code's output as it runs.
mic_scope.py is included in the Pathways folder. It requires
sounddevice, numpy, and pygame on the Pi.