Yellow Drum Machine - Ressy Version

I first saw Frits’ Yellow Drum Machine featured in Make magazine a while back, and felt compelled to make one myself, starting with the how-to. So, here it is! It also recently showed up on Design Sponge, randomly enough (about halfway down that post). The biggest differences from the original design are around the layout of parts like the board and the big speaker and the yellow wooden frame. This was based on the MAKE instructions and the online walkthrough, but with separate parts instead of the solarbotics kit.

I’m not very familiar with digital electronics in practice, so a few things caught me off guard, particularly how to wire up the digital outputs between output pins and V+ instead of output and ground, like I would have expected, and the wiring of the small speaker. What I ended up with was a little different from the YDM hookup list in the walkthrough, for whatever reason, but it works!

Some of my variations from Frits’ original instructions worked out well, and some less so:

• I ended up getting all-black treads, so to make sure I included some yellow I painted the wooden base before assembling the rest. I think the combination worked pretty well! I picked up a variety of little wooden panels and blocks from a craft store, and using a small miter saw and some files, all the parts fit together nicely with some interesting shapes. I mainly used superglue between large bare-wood surfaces and then painted the combination afterward. I was a little worried about the strength of it (without hot glue or epoxy for the most part), but, so far so good.
• I cut the antenna I found a tiny bit too short to use as an axle, so instead it has a dowel with pennies glued to the ends.  (Looks a bit goofy, but it does the job.)
• As some comments in the original how-to mentioned, I had to connect the speaker output before the darlington transistor on the Picaxe board to get audible volume. (Pin 21 on the diagram on page 2 of the little Picaxe packet corresponding to output 0, which is pin 11 after the darlington driver.) I can’t remember why, though.
• I tried to use header pins instead of directly soldering wires to the rangefinder, which was good in theory-- except that they got in the way of the robot’s left arm when swinging the head! I then soldered extra pins on those pins at a right angle, with a struggle and even some glue to get them to stick. If I’d planned it out from the start I could have just used something like these right-angle header pins.
• Spacing out the arms more creates a problem when it finds something tall and narrow like a table or chair leg-- it’ll air-drum to either side of the object in a pretty silly looking way. The left arm is made from a piece of antenna, and while the tuning procedure helped, it’s still just a bit too heavy.
• I superglued a little switch to the back of the battery pack.

Even with some of the goofy mess-ups, I'm very happy with the result and grateful for the concept-- thanks Frits!