r/arduino • u/hjw5774 400k , 500K 600K 640K • Aug 08 '26

Look what I made! Cheeky weekend project: Ambient Light Datalogger

Post image

On Wednesday 12th August, the UK is set to experience a partial solar eclipse (approx. 93% obscuration where I am) so decided to build an ambient light data logger to record the event.

The sensor is a BH1750 ambient light sensor that records the lux levels to an SD card with a date and time stamp from the DS3231 RTC. The measurements are taken every 8 seconds with the Arduino going in to low-power mode in between readings.

Power is provided by an 8000mAh cell connected to a "solar" charge controller - but the solar cell is disconnected and only used as a USB charging port. A boost converter takes the nominal 3.7V and raises it to 5V.

Added a simple LED to give a visual indication of the system status: 5 flashes at start up, 1 flash after a successful reading, and permanent illumination if there is a fault with initialising a component.

Currently on test in the garden to get some baseline data.

10 Upvotes

92% Upvoted

3 comments sorted by

3

u/tipppo Community Champion Aug 08 '26

Great project!

2

u/hjw5774 400k , 500K 600K 640K Aug 08 '26

Results from Test #1.

A total of 3,254 measurements over approximately 7 hours, and the LiPo cell voltage still measured 4.01V indicating a nominal 80% state of charge.

The maximum value recorded was 23,060 lux. However the area of interest between 18:00-20:00 UTC has a range of 1,740 lux, giving much 'cleaner' data which will be better for seeing any effects of the solar eclipse.

2

u/babydonthurtme2202 Aug 11 '26

Awesome project! Love how you provided a picture labeling each component, great for visual learners who aren't familiar with schematics!