As a Christmas present from my sister, I received a Solarbotics Squid Hunting kit. This is a laser-cut wooden kit with a small PCB to assemble and a couple of solar panels. The sculpture has a small submarine, giant squid and a kelp forest for the support. Small fish are swimming through the kelp.
As the sun shines on the panels it charges up a supercapacitor and then that is periodically discharged into the motor to drive a propellor. The motor runs for about 2s and then the sub/squid coasts for another 30s or so.
The kit has clear instructions and is easy to assemble. You just pop out the number pieces and slot them together. I used a little PVA glue applied with a cocktail stick to keep it all rigid.
The soldering is straightforward but I do plan to add in an on/off switch so that it does not leave the super cap partially charged. That’s the reason the solar panel is slightly wonky in the above picture. As I was building it in the evenings, testing the motor assembly was challenging as it does not run too well from house lights, preferring direct sunlight.
The circuit that drives the sub is called a “Miller” solar engine and is based on the work the Beam Robotics movement. Thanks to Jeremy for reminding me about this. These Beam ( Biology, Electronics, Aesthetics, and Mechanics) Bots were designed to have very simple analogue components and to run from small cells or solar panels with simple movement like animals or plants.
This particular variation of the circuit uses a Microchip MCP112 voltage trigger, a device designed to help with resetting microcontrollers when the supply voltage is low, this results in very low current loss use and hence longer running time.
All in all a fun kit and it was good to have a refresher on beam bots.