Power consumption of the hardware is at about 2-4 µA in idle sleep mode. To get there you have to cut the PCB trace for the power LED of the Grasshopper (please see the zip files). And you also have to remove pull-up R5 on the HX711 SparkFun board. Another important component to save power is the Schottky diode D1. It needs to be a diode with a very low reverse current. Otherwise the battery will drain via the solar panel e.g. during the night. And last but not least there is the voltage divider R1, R2 used to measure the battery voltage. The Grasshopper can switch on/off the divider via transistor Q3 so it only uses power while measuring the battery voltage.

To disable the chip antenna of the Grasshopper you have to remove the 0 Ohm resistor next to the IPEX connector (please see the zip files).

The scale is inserted into slits on both sides of the birdhouse (please see the zip files). There is a Millimeter of room on all sides for the scale to move around. The reason for this floating type of mount is the wood contracts and expands due to moisture/temperature and would otherwise exert pressure on the scale. In version 3 the scale is now mounted on rubber standoffs.

The HX711 in the birdhouse uses the 3.3 V supplied by the Grasshopper both as analog and digital supply voltage for the ADC. The SparkFun board is designed for AVDD = 5 V analog voltage. To use the internal analog supply regulator with AVDD = 3.3 V you have to change resistor R1 from 20 k to 10 k Ohm (please see the zip files). If you feel skilled at soldering you might want to try reusing 10 k pull-up R5 (which needs to be removed anyway to save power) to replace R1. Using the HX711 internal analog supply regulator helps reduce noise for the load cell measurements.