A major part of the appeal of RC cars is the detail that can be put into them. It’s not uncommon for a high-end RC car to have a full interior, working headlights, and even steering wheels that actually turn. But for obvious reasons related to size constraints, it’s rare to see anything functional inside of an RC car. That’s why Cpomeroy2’s tiny, working RC car speedometer is so impressive, and they have a tutorial explaining how they made it.
This speedometer was created for a lightweight Land Rover RC car, and as you can clearly see in the video, it is very small. In fact, the entire gauge cluster is less than 5 cm, and the speedometer itself is a mere 1 cm in diameter. There also wasn’t a lot of room inside of the RC car for the components to drive the speedometer, so Cpomeroy2 had to find the smallest components available.
The microcontroller that they chose to drive the speedometer is a Microchip ATtiny85, and it’s one of the smallest microcontrollers you can find in a prototype-friendly package. That was programmed in the Arduino IDE through a Tiny AVR programmer, and directly drives an unbelievably tiny stepper motor that moves the needle in the speedometer. Cpomeroy2 doesn’t provide any detail on how the gauge cluster itself was constructed, but experienced RC car enthusiasts should be able to figure that part out themselves.