Light intensity sensor and calibration

Using Arduino Project Guidance
1

Dear Arduino-fellows,

There's quite a lot information about light intensity sensors, which is why I would like to reach out for your help.
The requirements I have for the light sensor are:

  1. below 5€
  2. should be calibrated in lux

I have thought about following approach:
Using photoresistors:

and for calibration, a lux meter:

What do you think about this method? Is it too time intensive? Are there maybe sensors that come calibrated off-the-shelf with I2C connection or even some analog off-the-shelf calibrated ones?

Best and thank you!

2

there are IC module boards that offer output in LUX.
one does an analog output, another does a serial. both cost less than an UNO.

BH1750
TEMT6000
VEML7700

3

Thank you a lot for the useful suggestions, the BH1750 seems like a very good fit. I am going to test it.

4

It all depends on how exactly accurately you want to measure the illuminance. Just yesterday I was experimenting with photo diodes (DE192H) connected as shown in the attached image.

They seemed to work quite well. And it is simply a photo diode and a resistor connected to an analog input of the Arduino with 10 bit resolution.

They'd need to be calibrated, so you'll need to borrow a lux meter to work out a conversion factor and see how linear they are.

Definitely under $5 though!

I've seen however that the BH1750 costs about 3$ each, so also well within your price range.

For me, I haven't got much space so the photo diode and resistor is ideal for me.

PhotoDiode-Arduino.png
PhotoDiode-Arduino.png969×744 1020 KB

5

In all cases you need to match the response curve for the light wavelengths you are interested in.

Paul