Metrion

Notebook

Notes

Short engineering records with enough numbers, wiring detail, and code to repeat the experiment. New entries appear when a result is stable enough to be useful.

  1. SHT41 calibration against a simple reference setup
    Humidity and temperature offset checks with a repeatable household reference.
  2. ESP32 deep-sleep power: measuring the parts that still consume
    Current measurements across wake, idle, and deep-sleep states.
  3. Exporting home sensor metrics to Prometheus
    A small metric endpoint for household sensors and naming conventions that held up.
  4. Long I²C lines: slowing down before adding hardware
    Practical notes on pull-ups, clock rate, cable layout, and error counting.
  5. Choosing a small DC supply by measured load, not label current
    Sizing margin, idle losses, transient load, and temperature rise.
  6. Grafana dashboard notes: fewer panels, better questions
    What made a household monitoring screen readable after several revisions.
  7. Workshop enclosure airflow test with two 120 mm fans
    Temperature measurements from a simple intake and exhaust arrangement.
  8. Measuring a battery divider with the ESP32 ADC
    Divider current, calibration, averaging, and a practical firmware correction.