simple-spectro

Very cheap, autonomous and precise spectrophotometer for DIY biology and chemistry.

This project is maintained by Hackuarium

Calibration of the RGB leds

The light sensor generates a frequency that is directly proportional to the energy of the light, with a maximal value of 500 kHz.

In order to use the full range of frequencies, it is important to be at the closest possible to 500 kHz when testing with a water sample (indeed, more light goes through when a water sample is inserted than when there is no sample at all). To modify the intensity of the LEDs, change the 3 resistors labelled R, G and B.

By default the resistors are 1k which prevents any saturation.

There is a special mode designed to calibrate the resistors: menu -> Utilities -> Test LEDs.

If the resistors are not strong enough the sensor will saturate and a value just over 50000 will appear (only one acquisition is done instead of 10, which means the LEDs only blink once). A correct value should be somewhere between 350’000 and 450’000.

Example (on D1)

R red Red (Hz) R green Green (Hz) R blue Blue (Hz) R uv UV (Hz)
1k   95240   1k     185230     1k     201170   22   9940
330  276500  330    416200     470    383320      
220  383700          330    506290      

Example (on D3)

R red Red (Hz) R green Green (Hz) R blue Blue (Hz) R uv UV (Hz)
1k   53670   1k     124882     1k     62626   22   11059
150  326653 330    290518     220    304900    

Example (on D4)

R red Red (Hz) R green Green (Hz) R blue Blue (Hz) R uv UV (Hz)
1k   97830   1k     245500     1k     142391   22   74888
150  Problem, just one blink 53513 470    430676     330    352858    

Example (on D5)

R red Red (Hz) R green Green (Hz) R blue Blue (Hz) R uv UV (Hz)
1k   103874   1k     295699     1k     243137   22   11484
150  problem 1 blink 330    problem 1 blink    330    problem 1 blink