Show HN: RF Hunter – Find hidden cameras and other devices

Original Article ↗ Hacker News Discussion ↗

Project overview & hardware

  • Device uses an ESP32 to drive an LCD and read an RF power detector module (AD8317-based board).
  • It’s point‑to‑point wired, no custom PCB; RF front-end handled by the detector module.
  • Auto‑calibrates baseline RF level on boot and then shows relative increases in signal strength.

Cost, commercialization, and assembly

  • BOM cost is reported around $30–$100 depending on source and pack sizes for parts.
  • Several commenters say they’d pay $60–$150 for a pre‑assembled unit.
  • Discussion of manufacturing economics: common “5× BOM” retail rule vs. skepticism that this applies cleanly to modular builds.

Detection capabilities & limitations

  • Detects strong, sustained RF transmissions (Wi‑Fi/cellular cameras, phones, laptops) within tens of feet, depending on antenna and environment.
  • Works well on continuous video or audio streams; poor at very short bursts or infrequent transmissions.
  • Baselines out constant local Wi‑Fi; tends not to trigger on idle beaconing, but on active data transfers.
  • Cannot detect non‑RF threats (e.g., passive cameras, wired recorders, people in closets).
  • Sensitivity and range heavily depend on antenna tuning and local RF noise.

Use cases: hidden cameras, game cams, drones

  • Intended uses: scanning Airbnbs, offices, and possibly detecting nearby drones.
  • For trail/game cameras, many units store data locally or wake only briefly via PIR, making RF-only detection unreliable unless they use cellular modems.

Alternative and complementary detection methods

  • Suggestions: thermal cameras (5 W devices stand out thermally), TinySA or SDRs for spectrum analysis, cheap “bug detectors,” optical lens detectors, and non‑linear junction detectors for powered‑off electronics.
  • Smartphone IR-camera trick discussed; effectiveness varies by phone and IR wavelength.

Technical debates & RF nuances

  • Some argue wideband directional detection is hard; ideas include log‑periodic antennas or phased arrays with AR visualization.
  • One critic claims the design cannot “really scan”; others rebut that the analog detector needs no programming and works in practice.
  • Multiple people stress that sophisticated implants using burst transmission or external excitation would evade this tool.