Light-Tracking BEAM Robot Head
Introduction: Light-Tracking BEAM Robot Head
Hey all! Super excited to finally be sharing this robot with the internet. It is a light-seeking robot that is entirely free-formed using BEAM style analog logic, that means no microcontrollers, and it runs entirely on solar power. It is a bit long but definitely watch my 30 minute explanation video if you want more detailed information on how everything works.
When I was very very young and just starting to get interested in electronics, these analog BEAM circuits were already going the way of the dinosaurs to make way for these newfangled PICAXE controllers or even an Arduino if you were lucky enough! As such, I only ever saw the tail end of the BEAM movement but something about those circuits still tickles me to this day. There is something about manipulating the movement of electrons at the most base level, no abstracting it with 1s and 0s, in order to make a pile of silicone... intelligent!
This circuit is much more finicky, took a tonne more work, and is nowhere near as powerful/versatile as a microcontroller based robot that would do the same thing, but I hope you will agree that there is something special about him. Maybe I am getting too philosophical here but there is something about his analogue nature that makes him more lifelike, gives him more personality than even a complicated digital program. Indeed, he was out of commission for just over a week while I waited for time to fix his motors and I really did miss him sitting there on my desk.In the demonstration videos you will even see a couple of animals/insects who I caught curiously inspecting the robot, I don't think they could tell if it was alive or not either ;).
In any case, I think that all of this philosophy is secondary to the main function of this robot which is... to look nice. I definitely think of this robot as an electronic sculpture and the "life" that the circuitry brings all just adds to the art.
All of my Instructables fall under 2 camps.
1. 51
Follow along with the instructions as I have shown.
2. Mostly just inspiration and not something to follow exactly.
This Instructable falls cleanly in the second category and you would definitely need to understand the whole schematic and do lots of prototyping and testing if you were to attempt this project or something similar.
I will try not write as much as I tend to do as this is already a very large project so if I miss anything just ask in a comment.
Finally, some of this is out of order as I was jumping ahead and making sections while waiting for other parts. So I have presented it in the most logical order build wise but there may be some continuity errors.
EDIT: For anyone curious, my marble machine and tiny photopopper are both still going strong!
Supplies
Tools
My 2 favourite hand tools are files and a jewellers saw. My 2 favourite power tools are my belt grinder and drill press. Alongside sandpaper and blowtorches for soldering these are the only tools I used to make the whole mechanical assembly.
For the free-forming I used a chisel tip soldering iron (only bringing out the fine tip for corrections I had to make to already densely populated sections of the free-forming). I also used a set of needle nose pliers from my local electronics hobby store and a pair of side cutters for all of the wire shaping.
Components
I cant list all of the components here so I will just list the important ones:
Solar panel: SM531K12L from digikey, 1.37W at 8.29V. It is quite pricey for a single panel but definitely the most efficient indoor solar panel I have come across at this size.
Motors: 15RPM 3V N20 motor (45RPM works also and were the motors I originally chose but they were too fast. I bought a lot of N20 motors to test and it would seem that the 45RPM and 15RPM use the same speed motor with different gearing, while the 30RPM motors use a weaker motor with the 45RPM motor gearing. So while 30RPM would probably be the better choice, the 30RPM motors I bought did not work with the circuit I designed.
ICs: 74HC240s for the octo inverters and a 74HC14 for the hex inverter for the audio processing.
Capacitors: There are many caps in this build but I wanted to mention that I generally chose long life electrolytics and high(ish) quality ceramics for a longer lifespan. 98