The adopted BEAM robot, Herbie

This is a special little Beam robot, one that started out as a last-minute entry into a robot contest. It may have lost the contest but it won many hearts.

A little correction, the LM386 is not technically an Op-Amp, it is a power amp. Although it is often referred to as such, it is designed to drive speakers not compare voltages. Ironicly this circuit uses it more as an Op-Amp.

Parts list and values.
-The chip - LM386 comes in a few versions with a dash at the end, they should all work.
-Relay - Any DPDT relay will work if it switches with your battery.
-Light sensors - I used IR photodiodes but any photodiode or even RI LED should do the job.
-Transistor - 3904 but again, pretty much anything will work. Pay attention to NPN vs PNP.
-Capacitor - I used 40uF, others can be used to adjust the backup time.
-Resistor - 4.7K

Everything else is pretty much what you have. It should work on anything over 6V and most small gear motors will work as well. The layout does not need to match mine at all, do whatever works for you.

This is based on the circuit used in the Junkbot book however there are a million variations out there.

[Solarbotics]

I ROFL'd when I saw my name come up on your video when you mentioned the book. I still have a sincere fondness for these simple circuits... Back to watching the rest of your video! Keep up the good work. 🤣

[Enigma]

Two nice things about the LM386 is that its common mode voltage output is Vcc/2 with a single supply. Also, it has 300mA current output which is sufficient to drive small motors. An op amp could concievably be used, but it would need proper biasing and an output transistor to drive the motors. Also, if you don't like the relay, you could replace it with an h-bridge at the expense of some additional parts.

[FabriuhR]

I found this channel through the previous video of the other beam robot, very cool content! I really liked the concept of these robots, it's nice to see something so striking and cool made with such basic electronics!

[TimHollingworth]

That's brilliant. I really enjoyed the simplicity of construction and circuitry. With the complexity of seeing the movement towards light and avoiding shade. Makes me want to build one with the chip that I must have in my junk box. Like you I'm not so sure about the relay but my limited brain won't be able to figure out an electronic alternative. Thank you, most inspiring.

[GregTasi]

It was also one of my first robotics projects! Good memories!

[simonabunker]

That's a clever and simple design!

[ebutuoytm]

Glad to see somebody keeping the BEAM community alive. I still have that book and the few bug bots and walkers I've made over the years, hope to get back to it someday. Great content!

Edit: Uploaded an example of one of my bots to my channel for giggles.

[techman]

It took me two videos to subscribe 😂 excellent content

[evanbarnes]

Dude I love what you're doing on your channel! I had the same book, and we clearly had a similar experience with BEAM back around 2000 or so. I love seeing people keep this alive. What's next for you? Hider?

[DadofScience]

Nice! Never seen that before. I like it.

[kumardigvijaymishra]

3:34 An audio signal is a voltage signal. Noise reduction for voltage signal can be used on pin 7. How would it make insect behaviour noise-free?

[preethamkasireddy]

Awesome dude I love your videos keep up the good work i learnt a lot

[workinprogress]

i read about BEAM bots a few years ago, a lot of the sites were down, we should maybe start some sort of wiki to archive the stuff that is still around

[kamelraghdi]

The design of the robot resembles Lisa's turtles from the 1950s; it was almost the first autonomous robot.

[curtisnewton]

the lm386 is NOT an op-amp, it is an audio amplifier
check your shit beforehand