Keep running.
Keep your count.
A wearable and a track beacon that take lap counting off your mind, one quiet vibration at a time.
Proposed geometry and materials. Physical fit, radio performance and weather resistance remain untested.Try the wearable.
Walk through setup, a full run, duplicate prevention and recovery. Time and radio packets are simulated. No device is connected.
Your initial presence never counts as lap one.
Set up a run
“One circuit” feeds weak departure packets, advances synthetic time, then feeds a qualified return into the reference state machine. “Wait near” cannot add another lap.
Built for the track.
Large count, two buttons and replaceable straps. A sunlight-readable screen takes priority over matching the dark display in the illustration.
58 × 58 × 26mm
Provisional body envelope for purchasable breakout boards. A 500mAh battery, vibration motor and 24mm strap.
85 × 105 × 40mm
Green status light, USB power bank and weighted stand. Begin testing at wrist height outside the lane.
46 × 50 × 17mm
Target after custom board and enclosure work. Under 55g is an unverified design goal.
The enclosure file is an editable envelope, not fit-verified production CAD. Board mounts, USB geometry, seals and button actuators need measurement and detailed design.
Price the whole job.
One wearable + one beacon. USD, 17 October 2026. Core parts use published prices; fabrication, tools and labor use explicit planning assumptions.
Parts, basic tools, shipping, estimated tax and 25% cash contingency. Your engineering time is additional.
116 engineering hours at $100/hour, procurement and 20% project contingency. Requires actual embedded implementation and track testing.
Adds custom PCB, compact enclosure and integration iterations. Certification, manufacturing tooling and commercial launch are separate.
The DIY cash breakdown
Download itemized BOM ↓Adjust the engineering rate
This is sensitivity analysis, not a contractor quote. Hours stay at 116; the procurement estimate and 20% reserve stay in the calculation.
Offline baseline: $0/month cloud or subscription. Optional UWB feasibility work is approximately $4,714 extra and needs review of the intended outdoor radio use.
Count eight real laps, once each.
Observe every crossing, compare the event log, test both wrists and document every miss or duplicate. Then verify setup, readable output, haptics, battery life and recovery.
A reviewable design, before fabrication.
The interaction demo and behavioral model are implemented. Physical hardware, radio calibration, embedded firmware, enclosure fit and environmental claims remain unverified. Official timing and group use require a different validation scope.