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| Cheapest way to check if a UVC bulb is as advertised? |
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| pipe2null:
So... I'm thinking I need to split this into 2 different projects to consider, and then choose one to proceed with, depending on cost, benefit, and likelihood of success building this myself. In either case, I am assuming that the measurements/readings would be obtained with a scope and/or cheap dmm, 'cause that's what I have ;) : Solution 1: Cheapo UVC detector: $30 photodiode + parts for ultra low bias current amplifier (haven't messed with op amps in a looong time) https://media.digikey.com/pdf/Data%20Sheets/Photonic%20Detetectors%20Inc%20PDFs/SD008-2171-112.pdf The only real benefit I can think of for this is declaring the UVC LED products available on Amazon as scams. Or not? Seems likely, but don't know for sure since nobody's bothered testing them. Solution 2: Germicidal Power "probe": $350 photodiode + $225 BP filter + parts for whatever glue is needed to get a decent measurement using scope/dmm Use 10mm x 10mm active area photodiode: https://optodiode.com/pdf/UVG100.pdf Plus a bandpass filter similar to: https://www.edmundoptics.com/p/254nm-cwl-40nm-fwhm-25mm-mounted-diameter/22476/ I could be off my rocker, but I'm thinking you could reasonably measure the actual power of germicidal UV emissions with something like this? Can it be done without a UVC test source with known output (reference) for calibration? Thoughts? Any better alternatives I should consider that hasn't been posted? |
| Someone:
--- Quote from: pipe2null on April 04, 2020, 11:08:14 pm ---I could be off my rocker, but I'm thinking you could reasonably measure the actual power of germicidal UV emissions with something like this? Can it be done without a UVC test source with known output (reference) for calibration? --- End quote --- Those ideas still can't measure the output power of the source as: a) its spectral distribution is unknown b) its spatial distribution is unknown You really need to read some introductory texts on optics and/or spectroscopy and/or radiometry. There are specific instruments to measure irradiance at a target surface, and more specialised tools that apply weightings for specific measures: https://www.intl-lighttech.com/products/ilt2400-uvgi-0 You can't just magic something up out of parts unless you understand what the parts do and most importantly, what you are trying to measure. This thread is like the rush of people making radiation measuring equipment after the Fukushima Daiichi accident, you can measure "something" but its unlikely to be either what you think you are measuring, comparable to any specific units, or useful to assess safety. |
| Smokey:
Seriously.... just stick to the easy problems like making an open source ventilator! |
| james_s:
The easiest way is probably to sniff for ozone, the UVC lamps I have produce rather copious amounts of it. You can't cheat on the spectrum of a mercury discharge, the only corner they could cut on a "fluorescent" tube is to make the envelope out of glass rather than quartz. If it's glass it won't produce ozone so if it does you can be reasonably sure that it's producing UVC. Be careful as ozone is fairly toxic in high concentrations, along with the UV radiation being hazardous to biological organisms. Don't forget to keep your pets from being exposed too. It will also fade and degrade fabrics and polymers. |
| NiHaoMike:
--- Quote from: Ian.M on April 03, 2020, 09:30:37 pm ---Re: the OP's UV intensity comparison problem, probably the cheapest hobbyist friendly option would be to time the 'bit-rot' of a UV erasable EPROM. Program it all '0' then time till half the bits have become '1'. However you mustn't apply power while the EPROM is being exposed to UV, so its going to require you to rig up some sort of servo controlled shutter to obscure its window while you are powering and reading the EPROM. --- End quote --- I remember an experiment that involved repeatedly reading an EPROM while it's being exposed to UV. I forgot how much UV was used, but the EPROM was constantly powered during the whole process. --- Quote from: james_s on April 05, 2020, 03:00:52 am ---The easiest way is probably to sniff for ozone, the UVC lamps I have produce rather copious amounts of it. You can't cheat on the spectrum of a mercury discharge, the only corner they could cut on a "fluorescent" tube is to make the envelope out of glass rather than quartz. If it's glass it won't produce ozone so if it does you can be reasonably sure that it's producing UVC. Be careful as ozone is fairly toxic in high concentrations, along with the UV radiation being hazardous to biological organisms. Don't forget to keep your pets from being exposed too. It will also fade and degrade fabrics and polymers. --- End quote --- Some UVC lamps are filtered to block the really short ozone forming UV. |
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