Switcherooni Light Switcher

An automatic light switch flicker, controlled over bluetooth

Switcherooni started as a “what if I could flick the dorm lights from bed?” idea and turned into a three-iteration Bluetooth-controlled servo rig. I modelled and printed the enclosures, tuned the electronics, and built the firmware that listens for BLE packets and translates them into smooth switch throws.

Mk1 baseline

  • Took inspiration from James Hobson’s build but refactored the arm geometry to keep torque inline with the toggle.
  • ESP32-S2 prototype driving an S51 micro servo directly from USB power—enough to prove the concept, but torque-starved.
  • Fusion360 CAD printed on BambuLab X1 Carbon (PETG) with quick-release mounting so I could iterate overnight.

Mk2 refinements

  • Upgraded to a HS-311 servo for more headroom, reworking the enclosure for rigidity and better clamp distribution.
  • Learned the hard way that off-the-shelf servo CAD is rarely accurate—shimmed with washers to recover clearance and captured those tolerances in the next rev.
  • Separated the bracket and electronics bay to isolate vibration and make servo swaps painless.

Mk3 production build

  • Arduino Nano RP2040 Connect handles BLE, advertising on a three-second interval to stretch battery life (~4 days on three AA rechargeables).
  • Hex commands (0x01 / 0x00) fire position presets; firmware maps them to servo pulse widths with debounce logic so the switch never chatters.
  • Added a boost converter to give the servo a stable 6V rail while keeping the microcontroller happy at 3.3V.

Control + future work

  • Currently controlled via a barebones mobile BLE terminal—UI next on the list alongside scheduling and multi-device support.
  • Looking into swapping the Nano for an nRF52 and a proper Li-ion pack to push battery life into multi week territory.
Switcherooni Mk3 demo showing the BLE controlled thro (albeit failing).
Final CAD assembly with servo bay, clamp, and adjustable horn.

Next up: design a PCB to consolidate power management and BLE, then package the project for other lazy light switch aficionados.