ESP8266 Deep Sleep Mode - How to Use Deep Sleep Mode for Power Saving
GitHub - frolswe/esp-battery-logger: Simple project for the esp8266 using the power saving features of the chip to test the possibility of battery powered sensors.
Extreme Power Saving (0µA) with Any Microcontroller: Latching Power Circuit | Random Nerd Tutorials
ESP8266 ESP-01 Wireless Switch With Deep Sleep Mode : 4 Steps - Instructables
Window/Door Sensor - battery powered with relay or FET for backup - Project Guidance - Arduino Forum
Battery Saver Circuit
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