Adafruit GUVA-S12SD Analog UV Light Sensor Breakout - Tabletop Mounting - Compatible with Arduino, Raspberry Pi

• Add light sensing to your Arduino or Raspberry Pi project
• Requires soldering of header pines
• Easy to use

Extend your light-sensing spectrum with Adafruit Analog UV Sensor Module. It uses a UV photodiode, which can detect the 240-370nm range of light (which covers UVB and most of UVA spectrum). The signal level from the photodiode is very small, in the nano-ampere level, an opamp is tossed to amplify the signal to a more manageable volt-level. This sensor is much simpler than the Si1145 breakout, it only does one thing and gives an analog voltage output instead of requiring a complicated I2C setup procedure. This makes is better for simple projects. It also has a 'true' UV sensor instead of a calibrated light-sensor. To use, power the sensor and op-amp by connecting V+ to 2.7-5.5VDC and GND to power ground. Then read the analog signal from the OUT pin. The output voltage is: Vo = 4.3 Diode-Current-in-uA. So if the photocurrent is 1uA (9 mW/cm2), the output voltage is 4.3V. You can also convert the voltage to UV Index by dividing the output voltage by 0.1V. So if the output voltage is 0.5V, the UV Index is about 5. Please note, UV LEDs are 400nm, outside the range of this sensor, so if you're trying to test this sensor, don't use them. A UV tanning lamp or 'lizard-lamp' will work much better.