Building My Own Whoop For 50$ Pt. 1

DIY Fitness Tracker Project

The creator begins a DIY fitness tracker project, aiming to build one for about $50. They compare the cost with a Whoop subscription, described as costing up to $360 per year (with a cheaper plan under $200), and the Fitbit Air, described as costing $100 upfront, with an optional $100-per-year software plan.

Hardware and software

• The project combines a processor with sensors. The creator first tests them on a breadboard to confirm they communicate and produce useful readings.
• The boards support CircuitPython, which makes software development easier.
• Claude helped choose hardware, produce most of the software, and suggest wiring. However, the AI-generated instructions needed refinement: the initial wiring advice omitted pull-up resistors, so troubleshooting was still required.

Wearable design

The main challenge is moving from a breadboard prototype to a compact wearable enclosure. The creator iterated on a 3D-printed housing to reduce its height and overall size. The two halves are designed to snap together without glue.

An earlier working prototype became unreliable after repeated adjustments damaged solder joints; some parts were also affected during soldering. The creator is transferring the components into a new housing.

Sensor design considerations

The PPG sensor shines light into the skin and reads reflected light from capillaries to estimate heart rate, heart-rate variability, and oxygen saturation. Good skin contact is important to limit interference from outside light.

The temperature sensor’s chip also needs contact with the measured surface. To improve contact with the wrist, the creator designed a small metal slug that presses into the enclosure, with thermal paste between the slug and sensor. The idea is for the slug to warm toward skin temperature, though this still needs testing.

Current status and next steps

The device has been soldered, powered, and is running code, with sensor readings visible on a desktop. The creator reports some noise, particularly in the oxygen-saturation readings. The enclosure is large on the creator’s relatively small wrist.

The next video is expected to cover adding a battery, reducing signal noise, and collecting data. The creator also had Claude generate a sleep-tracking dashboard and hopes to test the device overnight.

The project’s parts list, code, and enclosure STL files are available through the creator’s GitHub repository.

Main speakers and sources

• GarageEngineered creator: Narrates the build, design decisions, and project status.
• Claude AI: Assisted with hardware selection, wiring guidance, software, and a sleep-tracking dashboard.