Light following bristle bot


There is one thing missing from all my projects so far…..Something that moves. Bristle bots are very similar to hex bugs but are built from toothbrush heads and pager motors. I thought the idea of bristle bots was cool but they were no brains to them until i seen this blog post where you could control one with a light. Essentially this light following bristle bot is just two bristle bots side by side so it would be steered.


Lets have a look at the hardware side of the build. Here is a bread board layout below. As you can see its just 2 bristle bots where the pager motor is controlled by a 2N7000 transistor which its speed is determined by the LDR (Light Dependent Resistors) and adjusted with a resistor trim pot. I also added a led to each one to show which pager motor is being activated, This makes it easier to see whats going on too.



Hardware list

  • 2N7000 transistor
  • LDR (Light Dependent Resistors
  • Pager motor
  • Resistor trim pot (10k omh)
  • Switch
  • Lipo Battery (3.7v 250mAh)
  • Battery connector JST-DS female
  • LED
  • Resistor (220 ohm)
  • Toothbrush

I have seen people build these on a bread board but I wanted to get a PCB made to make it smaller. This is my first analog project which is weird because there was no code to be written, which also meant I had to make sure it worked because I couldn’t fix it in code later.

I was looking for a way to fix the pager motors to the PCB, I came up with the idea of using tie wraps and a M3 mount hole in the PCB as you can see in the photo below



I decided to go with a small (250 mAh) libo battery. I didn’t know there were so many different JST connectors until I started looking for the right ones for my battery, The connector on my battery is a JST-DS if anyone else is looking. I got an external charger so all you need to do is disconnect the battery from the bot and connect it to the charger or have a freshly charged battery you could swap out


As I was researching this project I did see a few people were claiming that you needed to buy the expensive toothbrushes with the rubber slanted bristles but from my testing its not necessary. I just ordered the cheapest toothbrushes off eBay and they were fine.


YouTube – 


Github files –


6 responses to “Light following bristle bot

  1. Pingback: Light following bristle bot – OSH Park·

  2. Hey Drew, thanks for the PCB design!

    I had a thought when watching the video: what if the steering direction were reversed? When you light up the left LDR for instance it ends up moving away from the light!

    I was wanting to build one of these myself and also put it up on my site to make it easier for others to build: I forked your project on GitHub and started making it compatible with the site. I can’t quite figure out the BOM though. This is as far as I got with it (just a preview):

    It would be great to figure out exact part numbers so it’s easy to buy. Let me know if you would be happy for it to be put up on the main Kitnic site, linking back to your repo, and I’ll send you a pull-request with what I have.



    • Wow that’s a great idea about fixing the steering, Wish I had tested it before getting the board made.

      The stuff your missing off the BOM are

      2 x 2N7000 mosfet transistor
      2 x Pager motors
      2 x 10k ohm Trim Pot Variable Resistor Potentiometer
      2 x Tie wrap
      2 x Tooth brush
      1 x 250mAh 3.7v lipo battery
      1 x JST-DS female battery connector
      1 x 3 pin switch
      Some double sided tape or hot glue to attach the brushes
      Also you will need a lipo battery charger like in my video

      Im flatted that you want to put it on your site. Let me know if you need anymore info

      Happy hacking

  3. Pingback: Bristlebot with LDRs Becomes Light-Following Bristlebot « Adafruit Industries – Makers, hackers, artists, designers and engineers!·

  4. Pingback: Bristlebot with LDRs Becomes Light-Following Bristlebot – OSH Park·

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