Energy scavenger as Temperature and Humidity sensor

A project log for PTPM Energy Scavenger

Photovoltaic, Thermoelectric, Piezoelectric, Magnetic induction Energy scavenger

mileMile 07/15/2018 at 21:280 Comments

Image below shows Energy scavenger module in 3D printed enclosure. There is also ATmega328P arduino compatible board optimized for low power operation(only basic components, running on internal oscillator), ISM 2.4 GHz RX/TX module(NRF24l01+) and humidity and temperature sensor(DHT11). Energy is harvested by piezoelectric element and photovoltaic panel on top of the enclosure. There is also hole for external clip-on antenna but for running first tests long range capability is not needed.

Device in this configuration is located in backyard and is monitoring temperature and humidity and sending it to nearby node(located in house), periodically every 60 minutes. Data is logged and then plotted. Since there is not much data to transmit and distance from mode is not more than 50 meters low data rates of 250kbps and transmitter output power of  -18dBm are more than enough here. With this specs device consumes around 20uA in idle and around 7mA when transmitting. 

As it can be seen from from measurements conducted on photovoltaic panel in previous project log, panel can provide more than enough power for 24/7 operation.