The **GMC-500-R** is a digital Geiger-Müller counter manufactured by GQ Electronics. It is an upgraded version of the standard GMC-500 series, specifically designed for environmental radiation monitoring and data logging. ### Core Electronic Components The device operates using several key sub-systems that allow it to detect ionizing radiation and convert it into a digital readout. | Component | Function | Description | | :--- | :--- | :--- | | **Geiger-Müller (GM) Tube** | Radiation Sensor | Usually dual tubes (M4011) to cover high and low dose rates. It contains an inert gas that ionizes when radiation passes through. | | **Microcontroller (MCU)** | Processing Unit | An ARM-based processor that handles pulse counting, display logic, and USB communication. | | **High Voltage Module** | Power Supply | Boosts the 3.7V battery voltage to ~400V–500V DC required to charge the GM tube. | | **TFT LCD Display** | User Interface | A color backlit screen that displays CPM (Counts Per Minute), dose rates ($\mu Sv/h$), and historical graphs. | | **Flash Memory** | Data Storage | Internal non-volatile memory used for logging historical data points for later download. | | **Wi-Fi Module** | Connectivity | Allows the device to connect to the "GQ Cloud" to map radiation data globally. | --- ### Technical Specifications of the Electronics The electronics are designed for low power consumption while maintaining sensitivity to Beta, Gamma, and X-Rays. * **Detection Range:** 0 to 4250 $\mu Sv/h$ (Micro-Sieverts per hour). * **Sensitivity:** Dual tubes allow for more accurate readings; when one tube is saturated in a high-radiation environment, the second tube handles the overflow data. * **Power Source:** 3.7V Li-Ion rechargeable battery or via USB power. * **I/O Ports:** Mini-USB for charging and data transfer; 3.5mm jack for pulse output/audio. --- ### Operational Flow 1. **Ionization:** Radiation enters the GM tube, causing a momentary electrical discharge. 2. **Pulse Detection:** The electronics sense this discharge as a "pulse." 3. **Processing:** The MCU calculates the frequency of these pulses (CPM). 4. **Conversion:** Using pre-calibrated conversion factors, the MCU converts CPM into a dose rate (mR/h or $\mu Sv/h$). 5. **Output:** The data is sent to the LCD screen and stored in the internal flash memory.