On December the 3rd 2016, Nottingham Hackspace ran the second annual Nottinghack Crapthon. The Crapthon is a reaction against the fun of hackathons getting underminded by corporate sponsors who would like the events to be about promoting their products or recruiting, rather than making fun stuff. Also, we couldn't find a corporate sponsor.  The event is inspired by the Terrible Ideas HackathonHeboCon, and other fun events.

My contribution this year was to make this:


  • Arduino Pro Mini (5V version)
  • SG-90 servo
  • DFPlayer Mini audio module
  • 2W speaker
  • LM2596 DC-DC converter board

The DFPlayer Mini is very nice. I've used WTV020SD-16P modules the past, but have found them to be temperamental - having difficulty reading SD cards if not formatted in very specific ways, and requiring audio files in non-standard AD4 format. Not so with the DFPlayer Mini, which had no trouble with an SD card formatted with mkfs.vfat containing files in MP3 format which were encoded using Lame. The module is also capable of directly driving a 2W speaker, producing enough sound for my needs here. Docs and example code can be found in the link above.

I like the LM2596 DC-DC converter, although it's overkill for this project - I just happened to have one laying around so figured I might as well use it. These little boards take a DC input from 4.2-40V and output 1.25-37V, adjustable by the multi-turn pot, which gives quite good precision. If required they can provide a decent amount of current too. Worth getting a couple.

In keeping with the spirit of the Crapathon, the whole thing is just taped together, with no attempt made to make the mechanism robust or particularly useful. However, I'm somewhat interested in making a more robust and sophisticated version. I'd like to have the eye move in two axes rather than just left-right, and have some sort of sensing in the system.  To this end I started to make some models in Blender - a screenshot of which I shall leave here.