Pip-Boy 3000 Geiger/GNSS Mod Board
The module is designed as an instrumentable engineering platform: the high-voltage supply, pulse chain, counter, GNSS timing, and host stream can each be measured independently before the system is trusted.
Problem and constraints
The miniature SBM-21 enables a compact assembly but has low sensitivity, requires approximately 400 V bias, and produces statistically noisy low-rate readings. Fitting its switching supply, ESP32-S3, GNSS antenna, pulse chain, service port, and side-entry JST-SH host interconnect onto a 66 × 44 mm board adds mechanical and RF-coexistence constraints. Enclosure fit remains unverified.
Engineering approachArchitecture and implementation
The reviewed PCB uses a 600 V switch, corrected purchased-part footprints, 17 test pads, inner ground references, and Littelfuse 01000058Z/6049 solder-in tube contacts. MAX-M10S position and time arrive over I2C; the separate host UART carries the proposed fused telemetry. Converter regulation, firmware fault handling, tube mounting, and RF performance require prototype validation.
Signal chain
The tube pulse passes through a cathode pickoff, AC shaping, clamp, and TLV3201 comparator before reaching the ESP32 hardware pulse counter.
Data contract
Counts, smoothed dose estimate, high-voltage state, coordinates, altitude, fix quality, satellites, and UTC are combined in an NMEA-style $GM sentence.
Boundary
The design is for engineering and educational use. Prototype calibration, high-voltage insulation, enclosure safety, and RF testing remain open; it is not a safety dosimeter.
Open the project workspace
Open the companion workspace to inspect the project and its current development state.