Supply voltage: 4.5...5V DC
Terminals:
- 3.5mm jack socket: speaker/earphone output
- Pin row: 3p: TTL signal level output, 5V, GND
- Power connectors:
- 5.5 x 2.1mm DC socket
- screw terminal, 5.08mm
- PCB dimensions: 107.5 x 63mm

J305 GM tube features:
Radiation detection: beta and gamma radiation
γRay 20mR/h...120mR/h and βRay 100...1800
Tube material: Thin-walled glass.
Cathode: Tin oxide.
Operating voltage: 380...450V, recommended voltage 400V
Maximum operating voltage: 550V
Starting voltage: Less than 350V.
Maximum slope: 10% per 80V.
Background counting rate: Typically 25 counts per minute.
Operating current: 0.015...0.02mA.
Lifetime: 1 x 10^9 pulses.
Dimensions: Length 92 ±2 mm, Ø10 ±0.5 mm
Operating temperature: -40...55°C
Gamma sensitivity: 44 (60Co) (cps/mR h^-1)
Application: Personal dosimeters, radioactive survey meters and radiation detection in various materials.

Package contents:
- Assembled PCB
- J305 GM tube (attention, packaged separately)
- Plexiglass cover (1pc protective plate, not box)
- spacers 2x 4pcs
- USB - 5.5x2.1mm power connector
- Battery holder: 3 X AA (battery not included)
- Connecting wire 3p female-female
- Jack-jack cable 3.5mm