LEDscope

From neurotica.com

This is a low-resolution digital oscilloscope built around a grid of LEDs. I built this purely for fun. Projects like this appeared in electronics hobbyist magazines in the 1970s; the one that stuck in my mind was a 100-LED unit (10x10 matrix) built by Forrest M. Mims for a project book sold by Radio Shack. I had that book when I was about ten years old. I built that unit, but I have no idea what happened to it. A couple of years ago I thought to recreate it using a higher-resolution display matrix and more modern driver circuitry. This is the result. It's not quite done, but the basics are there and functional.

It's built around a PIC16F873 microcontroller clocked at 20MHz, with firmware written in C. The display matrix is a grid of 384 (24x16) painstakingly hand-wired T1-size red LEDs. The wiring is visible in one of the photos below. That took a long time and was pretty tedious, but it was really nice when I was done.

When it's finished, I'll put up some pictures of the unit displaying a waveform.

Photos

The mostly-finished unit.

Bottom view showing wiring.