Adafruit UV Sensor and response to UV Torch


#1

Hi ,
Does anybody know if the Adafruit UV Sensor https://shop.pimoroni.com/products/adafruit-si1145-digital-uv-index-ir-visible-light-sensor will respond to light from the torches that are easily available on Amazon such as https://www.amazon.co.uk/Vansky-Detector-Ultraviolet-Flashlight-Batteries/dp/B010XC36FU/ .

I don’t need it to give a really accurate value reading, just a strong response when the light is waved at it.

Thanks


#2

I am by no means an expert, but most UV torches emit light in the longer and comparatively safer UV-A wavelength which would register considerably lower on the UV scale than natural daylight.

If you check the datasheet section 2.4 page 15: https://www.silabs.com/documents/public/data-sheets/Si1145-46-47.pdf

You will see a graph relating UV index weighting to wavelength.

Since this sensor is reporting UV index and not a range of intensities by UV wavelength you might find that any other source of UV would occlude your torch- since the known effects of the wavelength of human skin are being used to derive a weighting that weights UV-A fairly low on the spectrum and UV-B much higher.

IE: Your UV-A torch might be very bright, but since its effect on human skin is negligible the weighting will cause all but the most high intensity of beams to register fairly low on the UV index.

You might have luck indoors, and you wont get a strong response since the torch is at the low-end of the scale, but you may get some response.


#3

Thats roughly along the lines that I was thinking. All the lights and LEDs that are shorter wavelength are much more expensive. it will most likely be used inside in and away from any daylight, so i’m hoping it works. Going to give it a go and see what happens.


#4

I have the Adafruit Si1145 hooked up to one of my Pi’s. Its paired with a BME680. Its a portable weather station. I use it to measure the UV index and ambient light level. The ambient light reading I use to adjust my display brightness. Dim in dark conditions and bright in high light conditions.
I don’t have any UV flashlights though.

The product description says " It doesn’t contain an actual UV sensing element, instead it approximates it based on visible & IR light from the sun." Is it going to do what you want?


#5

Maybe this instead, https://www.adafruit.com/product/2899

The VEML6070 in contrast does have a real light sensor in the UV spectrum.


#6

A Pimoroni Breakout Garden version would be cool, hint hint. ;) =)


#7

I’m going to try the VEML6070 and compare it with the Si1145. I will report back.


#8

I was only interested in the UV Index, not the actual level of UV light. I debated which sensor to get. The Si1145 calculates if for me without me having to any math so I went with it. In my case it doesn’t have to be super accurate so I’m fine with no real UV light sensor. In use its sitting in the shade most of the time anyway so it hardly ever measure the true UV index anyway, lol. I’ll take it out in direct sunlight now and then for a reading but thats about it.


#9

Have tested the VEML6070 sensor and the U.V torch. It does exactly what I want. When it is only exposed to normal fluorescent lights it gave a reading of zero and the UV torch gave a reading of up to approx 2000, depending on the angle and distance. That is perfect for my needs


#10

Thats very good to hear. Its nice when things work the way you want them too.


#11

Just saw this on Adafruit, https://www.adafruit.com/product/3964
Adafruit VEML6075 UVA UVB and UV Index Sensor Breakout
Looks like it does what you want and what I want.

Compared to our other UV sensors, this one actually does a pretty good job of getting accurate UV data. Unlike the Si1145, it has a real UV sensor, and in contrast to the VEML6070, it has dual band senors and an Index calculation algorithm. So far this is the best UV sensor we’ve got!

Might have to pick one of these up on my next order. Unless Pimoroni do one up for the breakout garden. ;)

EDIT: It looks like it doesn’t sense ambient light so it won’t work for me. Not as a direct replacement for my Si1145 anyway.


#12

I’ve just ordered some 365nM LEDs from Ebay as the U.V torch has too much visible light and shows up on camera which is undesirable for this project. Hopefully the VEML6070 will work ok with those, if not I might have to look at the VEML6075


#13

Just curious as to what your actually doing? You’ve perked my interest. =)


#14

Its an artwork around invisible technology, using infrared LEDs that can only be viewed through a phone camera (or ordinary digital camera, but most likely a phone in a gallery) and is stimulated by the U.V light on the sensor. All housed in a black box, again another metaphor for hidden technology.
I didn’t realise how bright the visible light of the U.V torch was and overpowers the I.R LEDs until I tested them together for the first time at the weekend.


#15

Ok, cool, thanks for the extra info.