User Tools

Site Tools


dbrooke_nodes:db04

This AVR Sensor Board V3 node has all components and headers installed and has a DHT22 as the sensor. The antenna is a 1/4 wave wire.

It is running from 3 AA NiMH cells installed in a battery holder salvaged from a time expired CO detector. The battery voltage reading appears to not suffer from thermal error despite having 4M7 and 1M resistors in the ADC divider.

2015-01-20 15:45 - Having spent some time sitting on the workbench in the utility room it was placed inside a plastic drink bottle with the bottom cut off and moved out to a sheltered corner of the garden under a tree.

2015-03-24 - Since the move to an outdoor location it has become apparent that the battery voltage does suffer from error under conditions of low temperature combined with high humidity.

2015-07-23 18:30 - Resistors in the battery voltage ADC divider changed to 470k and 100k and the batteries recharged.

2017-09-22 - The AVR shut down due to flat batteries but the RFM69 continued to transmit for 6 hours as can be seen by the raised threshold in this graph.

2017-09-29 - This hardware has now been re-deployed in the bathroom as DB07

2017-10-03 - Now using new hardware and housed in a box like DBD1. It is located at the other side of the garden where it should be shaded from the summer evening sun which had been causing higher than actual temperature readings.

dbrooke_nodes/db04.txt · Last modified: 2017/10/03 18:02 by dbrooke