CHOUR - Very low power Geiger-Muller counter PC-GM8
Device: Geiger counter
Date: 2013-2016
Type: PC-GM8
Brand: Chour
Main parts: GM Tube SBM20 or LND712, MSP430FR4133 Texas Instrument family processor, Imex module for High Voltage, e-paper and LCD display
Main characteristic: Average power consumption arround 60~80µA.
Software: Downloading page.
Version française : 
Product details
PC-GM8 is a Geiger-Muller counter with the following features :
- Measurement of radioactivity Beta, Gamma (tube SBM20) and in addition, Alpha if using a tube LND712.
- Permanent display of radioactivity rate in Count per Minute (CPM) on a LCD display.
- Display on an e-paper of the maximum CPM, the average over 24 hours in CPM, the battery level, the number of days of operation since the last power-on.
- Alarm by LED and/or Buzzer when the radioactivity exceed a given level.
- Setting the alarm threshold.
- Possibility to have a flash light (LED) or a beep (Buzzer) when a particle is detected.
- Rechargeable battery operation (typ 2400mA / h).
- Very low consumption allowing autonomy of several years in permanent operation without being recharged (typical 3 to 4 years).
- Memorize the last averages of CPM detections over one hour. Typically, 500 hours of measurements can be stored.
- Ability to connect (via USB) the counter to a PC under Windows and to use the software GeigerPC. This software is used to set the counter, retrieve the stored data, retrieve the minute count sent by the meter every minute, have statistics on measurements, etc. Connecting to a USB plug recharges the battery.
The technical documentation is available on that French page. The source code of the counter is available on that page. The GeigerPC Software for Windows is available on that page. It can be used to manage PC-GM2..8 Geiger counters.
Technical views
Schematic and PCB
Schematic
PCB
Modules used
FTDI232 LIPO charger
High Voltage Module generator from IMEX and its documentation (in French) and the e-paper display
Analog part
Truth table for the LED/BUZZER command
| Ai | Bi | Di | Comments |
| A1=0 | B1=Kb | D1 = Kb | Câblé. B1 suit la valeur de Kb/G1. Sortie signal. |
| A2=0=AL_BUZ | B2=0=EN_BUZ | D2 = 0 | Buzzer Off (no alarm or sound information). |
| A2=1=AL_BUZ | B2=1=EN_BUZ | D2 = 1 | Buzzer sounds. Used to generate an audible alarm. |
| A2=0=AL_BUZ | B2=1=EN_BUZ | D2 = Kb/G1 | Buzzer On. An audible signal is produced when a particle is detected. |
| A3=0=AL_LED | B3=0=EN_LED | D3 = 0 | LED Off (no alarm or visual information). |
| A3=1=AL_LED | B3=1=EN_LED | D3 = 1 | LED On. Used to generate a visual alarm. |
| A3=0=AL_LED | B3=1=EN_LED | D3 = Kb/G1 | LED On. A light pulse is produced when a particle is detected. |
Some pictures
Inside the counter
Connections
| Module | µP GPIO | Module | µP GPIO |
| Rx (FTDI232) | P1.0 Tx | Tx (FTDI32) | P1.1 Rx |
| Sleep (FTDI232) | P8.1 | DETECT1 | P8.2 (Timer 1) |
| AL_LED | P8.0 | AL_BUZ | P1.6 |
| S3 (Momentary switch) | P1.7 | S1 (A switch) | P2.7 |
| S2 (B switch) | P2.5 | BatEn | P8.3 |
| BatVolt | P1.3 | MOSI (e-paper) | P5.2 |
| CLK (e-paper) | P5.1 | CS (e-paper) | P5.3 |
| D/C (e-paper) | P5.0 | RST (e-paper) | P1.4 |
| BUSY (e-paper) | P1.5 |
| µP GPIO | Module | µP GPIO | Module |
| P1.0 Tx | Rx (FTDI232) | P1.1 Rx | Tx (FTDI32) |
| P1.2 | P1.3 | BatVolt | |
| P1.4 | RST (e-paper) | P1.5 | BUSY (e-paper) |
| P1.6 | AL_BUZ | P1.7 | S3 (momentary switch) |
| P2.5 | S2 (B du switch) | P2.6 | |
| P2.7 | S1 (A du switch) | P5.0 | DC (e-paper) |
| P5.1 (SCLK) | CLK (e-paper) | P5.2 | MOSI (e-paper) |
| P5.3 | CS (e-paper) | P8.0 | AL_LED |
| P8.1 | Sleep (FTDI232) | P8.2 | DETECT1 |
| P8.3 | BatEn |
Connections between then analog part and the processor part.
Case
