Rodbot

Rodbot - my first junkbot

My third robot came from the excellent book "Junkbots, Bugbots and Bots on Wheels" by Hrynkiw and Tilden. This book details seven projects utilising the BEAM (Biology, Electronics, Aesthetics, Mechanics) design ideals and recycled material. The projects include solar bots, Bicore bots and Beam bots. The authors explain each project in detail including the where the materials were sourced (eg old tape decks, modems, etc) the circuit diagram and construction techniques. In reality most of the IC chips used you are just going to have to buy but the ethos of recycling materials really struck something in me. The circuit designs are clear but I would have liked a little more explanation into the actual workings of some of the circuits. There was some explanation but at my low skill level I did have to do a few rereads on some of the projects.

Since reading this book I try and make sure all my projects use recycled/reclaimed materials. For example an old computer mouse (the roll ball variety) is a gold mine of parts (phototransistors, wiring, IR leds). Also a junkbot as a certain appeal and has more history attached to it.

Rodbot is based on the third project, a herbie photovore. A truly inspired design using an audio amp chip (LM386) and some photo detectors (I used phototransistors) to make a light following bot. A relay and bump switch is added so the bot can reverse if it hits an obstacle. The engine mounts are made out of hose clamps and chassis from cut offs from a cdrom case (the remains of the case from Squareabout). I loved the circuit. Simple but with a great deal of functionality and the junk construction was just fun to try. I did buy the 386 chip and the battery mount, but all the other components (including the wire) was recycled. The wheels came from an old battery car racer and give Rodbot great grip. I also reverse biased the phototransistors (ie put them in backwards to normal) to give a much greater response to light. With the phototransistors setup normal Rodbot turns within a 20cm arch. Reverse biased and he turns on the spot. I left the eye stalks attached with U-tack so that there were easier to direct. Also Rodbot pretty much flies along so crashes (and mild damage) are normal.

I plan to also make one of the Bicore designs from this book at a later stage. But even if you aren't going to make any of these projects the book itself is worth a read. Great ideas, well written and something I have reread a number of times.