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.
- 2N7000 transistor
- LDR (Light Dependent Resistors
- Pager motor
- Resistor trim pot (10k omh)
- Lipo Battery (3.7v 250mAh)
- Battery connector JST-DS female
- Resistor (220 ohm)
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.
Github files – https://github.com/facelessloser/bristle_bot_light_follow