IoT Geiger counter with ESP32, OLED display and thingspeak channel

• Low power mode for battery power supply with OLED display and click sounds, WiFi off
• WiFi mode for thingspeak data upload every minute using WiFi

Hardware

• Russian Geiger counter tube STS-6 at 400 V with ~5 MOhm
• High voltage circuit from ArnoR at mikrocontroller.net https://www.mikrocontroller.net/topic/380666, schematic https://www.mikrocontroller.net/attachment/273334/HystereseStepUpTLC555-2.png
• ~400 µs pulses generation using voltage divider, darlington transistor and TLC 555 timer
• ESP 32 board Wemos Lolin32
• OLED 128x64 with controller SH1106 at I2C
• Voltage supply from USB or power supply or 3x1.5V AAA batteries, works from 3.0 V up to 5.0 V

Software

• Eclipse sloeber project using Arduino library, ESP-IDF for sleep functions and u8g2 for display output