Electronics > Projects, Designs, and Technical Stuff

Cheapest way to check if a UVC bulb is as advertised?

<< < (8/9) > >>

pipe2null:
In all seriousness, I am REALLY not trying to beat a dead horse.   ;)


--- Quote from: Someone on April 05, 2020, 01:52:26 am ---a) its spectral distribution is unknown
b) its spatial distribution is unknown

--- End quote ---
a)  AFAIK (please correct if I am wrong), it doesn't matter if there are 1 or 15 different emitted wavelengths as long as they are all within the germicidal region.  If there is emission outside the germicidal range, then it doesn't matter for this application.  There is the issue of ozone creation at <200nm wavelengths which is outside of the band pass region of the filter, but for simplicity can leave that one single "measurement" to a sniff check.  For wavelengths that get attenuated toward the edges of the band pass region, well, I'm still thinking on that.  The intended purpose of the measurement for this application is to establish the minimum W/cm2 I can expect from an off the shelf product that doesn't come with a datasheet, so error due to attenuation that results in a measured value that is lower than reality is on the the conservative side of the line.
b) Well...  Isn't this an issue no matter what you are using to measure, DIY or NIST traceable light meter?  Most (but not all) of the UVC sources that might be useful are cylindrical, so hopefully that will reduce the complexity a little bit.  You make a good point though, relating point measurements back to the overall output pattern...


--- Quote from: Someone on April 05, 2020, 01:52:26 am ---You really need to read some introductory texts on optics and/or spectroscopy and/or radiometry.

--- End quote ---
I wholeheartedly agree.  If you have any recommendations on a technical ref book on the measurement of radiating sources/patterns/etc, especially if it includes the simplified equations for typical geometries (point samples -> total), I would appreciate it.  I ordered a technical reference for UVGI and its application to air and surface disinfection earlier this week.  It should have some basics on UVC source performance data, but I don't think it will have much on measurement.

Thanks for the pointer to the ILT2400.  Yep, that would take care of what I'm trying to do (at least once I get the tech reference info).  $3000 is a bit much for short term use, but I found a place that will rent it.  $420 for 2 weeks seems a bit steep, and I'll likely need it for longer than that, so the rental price is getting pretty close to the cost of the bandpass filter and fancy photodiode.  Hmm...

LaserSteve:
Check your PMs, Pipe2Null.  I just sent you a link to overstock from a reputable optical filter manufacturer.

Steve

Zero999:

--- Quote from: pipe2null on April 04, 2020, 11:08:14 pm ---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.
--- End quote ---
Is there any reason why your application requires LEDs i.e. having many on/off cycles, free from mercury (by the way low pressure germicidal lamps contain tiny amounts of mercury), no glass to shatter etc.? If not, just use mercury lamps. They're much cheaper and more efficient, than LEDs, given the same power ratings.

NiHaoMike:
Are there cold cathode or even capacitive coupled germicidal lamps available? The filaments are the main failure points of fluorescent lamps, and with no phosphor to degrade, a capacitive coupled germicidal lamp should last "forever".

james_s:
There's no reason one couldn't be made however I've never seen one. Properly cared for cathodes (filaments) can last a very, very long time. If you are going for long life, avoid instant start as that blows material off the cathodes every time it starts. Better electronic ballasts have what's called programmed start, they preheat the cathodes then gently apply the high voltage to strike the lamp, a good quality lamp on one of those can last tens of thousands of hours.

I've used electronic ballasts designed for those triple tube compact fluorescent lamps to run small germicidal tubes with good success. I replaced the failed ballast chokes in the ozonator in my hot tub with one almost 15 years ago and it's still going.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod