Bill of Materials
The EVDrive PCB already comes with all the small surface-mount parts pre-soldered (resistors, diodes, capacitors, fuse holder, LEDs).
Here is the list of everything else you need to get the car driving, including links, quantities, and rough prices.
Note on sourcing components
We have included links to Amazon listings, but these are just examples. You can find similar components on other sites. AliExpress has cheaper options and things that come in fewer quantities for saving money, but it's up to you for your risk tolerance and timeline for when you need the parts. AliExpress tends to take two weeks to ship items to the US.
Parts List
| Component | Qty | Est. Price | Link | Notes |
|---|---|---|---|---|
| ESP32-S3 DevKitC-1 | 1 | ~$15.00 | Amazon | Get the official Espressif board (N8R8 recommended). Clones sometimes have different pin spacing and won't fit the headers. |
| TMC2209 Stepper Drivers | 2 | ~$14.00 (pair) | Amazon | Standard StepStick footprint. Runs silent and gives smooth microstepping. |
| AS5600 Magnetic Encoders | 2 | ~$8.00 (pair) | Amazon | 12-bit non-contact rotary encoders. Make sure your kit includes the small diametric circular magnets. |
| MPU-6050 Gyro / Accelerometer | 1 | ~$8.00 | Amazon | Make sure to get the version with header pins pre-soldered so you can plug it straight in. |
| NEMA 17 Pancake Stepper Motors | 2 | ~$12.00 ea | Amazon | Short-body / pancake style (~22.6 oz-in). Plenty of torque for EV while keeping weight down. |
| XL6009 / XL6019 Boost Converter | 1-2 | ~$6.00 | Amazon | Steps your battery voltage up to 12V–24V for the stepper motor power rail. |
| LM2596 Buck Converter | 1 | ~$7.00 | Amazon | Steps voltage down to clean 5V to power the ESP32 and logic headers. |
| Rechargeable AA NiMH Batteries (8-pack) + Charger | 1 set | ~$18.00 | Amazon | 2800mAh NiMH cells. Good, reliable power source that fits easily within competition battery rules. |
| AndyMark 3" Sushi / Stealth Wheels (1/2" Hex) | 2 | ~$8.00 ea | AndyMark | High-traction rubber wheels that slide directly onto standard 1/2" hex axles. |
| 12mm Ball Caster (15mm Height) | 1 | ~$8.00 | Amazon | Low friction front/rear ball caster for ground clearance and balance. |
| RH Circuits EVDrive Board | 1 | ~$20.00 | Order Page | Main circuit board with surface-mount components pre-assembled. |
| 3D Printed Chassis & Modular Parts | 1 set | ~$5.00 filament | Chassis CAD Downloads | Self-printed in PETG or Tough PLA from official STEP/STL files. Fulfills Science Olympiad kit modification regulations. |
| M3 Machine Screws & Threaded Inserts | 1 set | ~$9.00 | Amazon | Assorted M3 x 6mm to 16mm screws and M3 x 4mm heat-set inserts for securing motors, PCB, and front bottle pusher. |
A Few Notes Before Ordering
- ESP32 S3 DevKit: Buy the official devkit from Espressif, as the common ones from AliExpress are clones and have a different footprint and won't fit in the pins.
- Batteries: Standard alkaline AAs drop voltage quickly as they drain, which will change your motor acceleration curves between runs. NiMH rechargeable batteries hold a much flatter voltage curve during testing.
- Magnets: Don't lose the tiny circular magnets that come with the AS5600 modules. They need to be glued or pressed into the center of your wheel axles about 1mm to 2mm away from the sensor chip.
- Wire & Connectors: Having some spare 22-26 AWG silicone wire, 2.54mm Dupont crimps / jumper wires, and heat shrink on hand will make wiring up the motors and converters much easier.