BEAM Dragonfly Causes A Flap

Normal people throw away stuff when it breaks. But not people like us. Or, apparently, [NanoRobotGeek]. A cheap robotic dragonfly died, and he cannibalized it for robot parts. But he kept the gearbox hoping to build a new dragonfly and, using some brass rod, he did just that.

The dragonfly’s circuitry uses a solar panel for power and a couple of flashing LEDs. This is a BEAM robot, so not a microcontroller in sight. You can see a brief video of how the dragonfly moves.

Really, though, the neat part of this is the fabrication of the wings using soldered brass rods. The head has the flashing LEDs as eyes. The secret sauce, of course, is the gearbox. If you were going to replicate this project, you’d probably have to figure out your own gearbox modifications unless you just happened to get the exact same toy.

In addition to LED eyes, the dragonfly also has a capacitor bank on its tail. This isn’t aesthetic. The wings run on a FLED-based solar engine circuit. The LEDs and the capacitors work to accumulate and discharge solar power allowing the dragonfly to flap even when there’s not enough light to directly power the motor.

It turned out that the dragonfly needed just a little more juice, so [NanoRobotGeek] hid an extra capacitor to increase the bank size.

We wonder if [Kerry] could make his dragonfly badge flap? We know it is cheating, but we prefer the BEAM robots to have a few smarts to them.

11 thoughts on “BEAM Dragonfly Causes A Flap

  1. Great to see people still making BEAM robots & circuits. It’s tech that’s really worth looking into for people interested in analog electronics. Solar engines, walking robot “brains”, a solar pendulum, charge pumps, analog counters, chirping circuits, circuits that listen & fire signals, lots of interesting ideas that can be applied in creative ways in robots.

    Now’s also a good time because I’m afraid some of the designs and discussions might get lost if people don’t search them out & back up stuff, e.g. the old alt-beam mailing list, and the Yahoo BEAM robotics group. There are a ton of fascinating circuit designs, in particular from Wilf Rigter. I’m still trying to track down some of the circuit schematics & attachments from the Yahoo group…

    1. Something I feel the world at large is forgetting entirely is Analog. I know I have barely ever in my life considered how to make use of it as for my entire life digital has been the default and available solution (Old enough to just about remember the tail of cassette tapes and VHS and be just barely mature enough for the original lego mindstorms RCX). Not through lack of interest I’ve just never spent enough time with the right book/forum to get really sucked in or had a project that screamed at me I needed to use this type of method.

      So if you have some engaging books or links to point to that still exist or are on the internet archives I’d be interested. Finding good resources for something you barely know a thing about is the hardest thing on the web.. Once you get started its so much easier to use the right search terms and evaluate the quality of what you find.

      1. Yep, almost all my experience was with digital electronics, but I’m really enjoying playing around with analog lately. One interesting aspect of many BEAM designs is the reliance on Schmitt trigger inverters and inverting buffers (I guess mostly used in digital applications), but used in an analog-ish way as oscillators.

        As for books, Tilden & Hrynkiw’s “JunkBots, Bugbots, and Bots on Wheels: Building Simple Robots With BEAM Technology” is a good start with used copies under $10. From there, I’ve been doing some deep (and not so deep) googling. has lots of BEAM stuff archived. has a lot of Wilf Rigter’s posts to the old alt-beam list. Check out the “BEAM SONICS” post there — it has a little bit of everything: electret mic, transistor preamp, “Nv & Nu neuron” sound level/envelope detector, charge pump, analog counter, and oscillator/piezo output.

        The Yahoo group seems to be where the list moved around April 2000

        Kind of a pain to navigate and some/many of the attachments may not show, but with patience and perseverance it can yield some info.

        1. Hey all, Im actually the one who wrote this Instructable. Very surprised to see it here on hackaday but will hopefully be making some more interesting circuits (like the 2 dof light seeking head that features in the video) once my university term ends =P.

          And yes Espectra, researching some of these circuits on the web can at times be damn near impossible but Im not sure what to do about it. I know there is someone on the forums who made this site to try and archive bots which I am very grateful for and has a tonne of sample circuit diagrams most of which without description unfortunately. Im not sure how to get more people connected though. I would normally suggest a facebook group however they are not so easy to navigate when looking for information and there already is one with 3000+ members that is completely dead. I really want an easy way to connect with people like you two, any suggestions Espectra or Foldi-One?

          1. I don’t have any great suggestions for discussions. There IS a subreddit for beam robotics FWIW. It seems pretty empty, but there’s nothing stopping people from posting there. In fact, I think it was the electronics or another subreddit where I found out about BEAM tech when someone mentioned it in a comment.

            One thing I’m focusing on is finding BEAM stuff that’s disappearing from the net these days before it actually goes “poof!”. A free Google sites page could be set up for archiving things, I suppose. Looks like you can embed a Google group for discussion as well.

          2. Yeah, not got any great ideas. I think just document what you do, keep the sources you used to create it.
            As espectra is doing grab copies of anything useful you find. Maybe even host a curated collection of this stuff/write a book/pdf.

            To get more people interested have a collection of well documented samples touring maker spaces perhaps? Shine a little light on clever circuits that don’t need the microcontroller among those that already have interest in making stuff.

  2. I hate acronyms without definition AWD?


    BEAM robotics (from biology, electronics, aesthetics and mechanics) is a style of robotics that primarily uses simple analogue circuits, such as comparators, instead of a microprocessor in order to produce an unusually simple design. While not as flexible as microprocessor based robotics, BEAM robotics can be robust and efficient in performing the task for which it was designed.

    BEAM robots may use a set of the analog circuits, mimicking biological neurons, to facilitate the robot’s response to its working environment.

  3. My issue with making the FLED style solar engines is most of the FLED’s you find out there are chip controlled inside the led and don’t really work right with this circuit. Where the heck would I find the proper old style FLED’s that were used for this type of solar engine?

    1. Yeh, I’ve never built a FLED-based solar engine (SE), partly because I’m not especially familiar with FLEDs and figured they were somewhat of an anachronism for BEAM stuff. I also haven’t built any 1381-based solar engines because I’d prefer to use more generic parts.

      To that end, I’ve built a few “Easter solar engines” and dabbled with a type 3 SE — supposedly triggers when charging current drops off rather than when a set voltage is reached.

      Also dabbled with basic zener-based SEs, the earliest and most primitive type, but using forward-biased LEDs rather than a reverse-biased zener diode. LED color determines the trigger voltage.

      That maybe uses the fewest parts (among discrete SEs) but is apparently very finicky with the motors it’s willing to drive.

      They all seem to require some tweaking. Which maybe means I should actually look into FLED or 1381 SEs. Haha. Anyway, the point is that in theory, you should be able to swap in your favorite type of solar engine for most BEAM creations.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.