I would like some assistance with solving a challenge which likely has a simple solution.
I am developing a remote, battery powered RH/Temp sensor unit using the nodeMCU ESP8266 (ESP-12e).
Each unit is powered by a 3.7V, 1200mAh Lithium Ion Polymer (LiPo) battery connected directly to GND and 3.3V (the ASM1117 regulator is bypassed). A DHT22 RH/Temp sensor is connected to GPIO4 as a 1-wire sensor and functions within specified parameters.
Using deep sleep mode with periodic wake ups, I should be able to run the remote sensors for at least 2 weeks. Even with the fan (mentioned below) running for a very short period prior to each wake up.
The challenge I have encountered is that before the sensor takes a reading, I would like to turn on the fan LINK (3.3V 20mA) for 3-5 seconds using an available GPIO pin.
The max current draw on a GPIO pin, for the ESP8266 (ESP-12e) is 12 mA.
Given my inexperience, I do not know how to make up the additional 8+ mA of current demand from the load of the fan. I know that the battery can handle it, but I don't know of a device (relay?), within the specifications of this application, that would provide what is needed. I have little knowledge of transistors, but I think that may be the device I need.
I am open to suggestions. Thank you for any advice you can contribute.