Cheap UV-C wand investigation: no light

Thread Starter

Lectraplayer

Joined Jan 2, 2015
121
I'm investigating a UV-C wand that won't give me light to disinfect with, and so far, it appears that I am getting energy to the bulb, but am unsure how much the tube actually needs to discharge. (Be careful with these, though. UV-C light can cause many health problems.) I think the bulb was not made properly at the factory as of right now, as I am getting a good couple hundred volts, though my DMM lies due to the high frequency, and my oscilloscope doesn't have the range to measure the value. All wiring looks to be in decent shape. I would also like to know where I could find bulbs to put in something like this, even if it isn't the same gas (like a neon or cold cathode fluorescent tube) or if I would have to learn neon signmaking to be able to make something to go in it. It appears to be a fairly standardized u-shaped tube about 5 inches long by 1/8 inch tube diameter, and just over 1/4 inch overall width (both tubes). Ballast looks to be quite simple, and advertises a safety feature where it supposedly turns the light off if it isn't shining down, but I doubt it has this feature, as orientation doesn't change the voltage going to the bulb. I'm assuming the bulb is an argon/mercury in quartz tube, though I am unsure the strike voltage. (Again, no idea where to find a datasheet or spare tubes, regardless of composition.) Any tips on where to look?
 

Thread Starter

Lectraplayer

Joined Jan 2, 2015
121
This is the device in question. Although I could just buy another, since they are sold almost everywhere now, I'm really wanting to learn a bit more about gas discharge lighting with it vs necessarily getting UV-C from it. I also figure that I should be able to track down the bulbs used in it, as they had to come from somewhere.
 

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Thread Starter

Lectraplayer

Joined Jan 2, 2015
121
Only in shape. Looks like you have a standard BX bulb, which is not what I have. The entire wand is probably about the same size as the bulb you linked. Like I was saying, the bulb is actually a very small cold cathode type tube of some sort.
 

wayneh

Joined Sep 9, 2010
17,152
Only in shape. Looks like you have a standard BX bulb, which is not what I have. The entire wand is probably about the same size as the bulb you linked. Like I was saying, the bulb is actually a very small cold cathode type tube of some sort.
Any hints on the bulb itself? Knowing the base type and dimensions would narrow the search. Any writing on the bulb or base could be very useful. But it's possible it's a custom bulb and simply not available.
 

Thread Starter

Lectraplayer

Joined Jan 2, 2015
121
It appears to be some sort of cold cathode fluorescent derivative, and is about the same diameter. All the small UV-C devices I'm finding appear to use the same exact bulb best I can tell, or at least something very close, and I doubt something this cheap and common would be a custom job. ...then again, I could be wrong. I may do better to find a bunch of busted screens and salvage the lamps out of them for my purposes. I'm sure I could fashion a bulb just like it with some practice.
 

Marc Sugrue

Joined Jan 19, 2018
213
I'm investigating a UV-C wand that won't give me light to disinfect with, and so far, it appears that I am getting energy to the bulb, but am unsure how much the tube actually needs to discharge. (Be careful with these, though. UV-C light can cause many health problems.) I think the bulb was not made properly at the factory as of right now, as I am getting a good couple hundred volts, though my DMM lies due to the high frequency, and my oscilloscope doesn't have the range to measure the value. All wiring looks to be in decent shape. I would also like to know where I could find bulbs to put in something like this, even if it isn't the same gas (like a neon or cold cathode fluorescent tube) or if I would have to learn neon signmaking to be able to make something to go in it. It appears to be a fairly standardized u-shaped tube about 5 inches long by 1/8 inch tube diameter, and just over 1/4 inch overall width (both tubes). Ballast looks to be quite simple, and advertises a safety feature where it supposedly turns the light off if it isn't shining down, but I doubt it has this feature, as orientation doesn't change the voltage going to the bulb. I'm assuming the bulb is an argon/mercury in quartz tube, though I am unsure the strike voltage. (Again, no idea where to find a datasheet or spare tubes, regardless of composition.) Any tips on where to look?
You are aware UV-C is invisible?, its radiation as opposed to visible light. Be very careful working with it as it can cause significant damage to your eyes & skin without you realising.
 
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Janis59

Joined Aug 21, 2017
1,332
By picture it looks like day-light lamp without of luminifore. Firstly, it characteristic wavelength is about 320 nm what is bactericide but is not any viracide. For viracide You need 254 or better 200-230 nm. But anyway, test the coil, isnt it broken, and test the starter. No, as the most first test do the nitting still is alive, must be few Ohms.
 

Janis59

Joined Aug 21, 2017
1,332
UV-C is invisible.Be very careful, can cause significant damage to your eyes & skin
Yes and No. If work is assumed hours then yes. If onlu one or two minutes are assumed, then dangerous power starts with about 1 kW, whilst the lamps in photo is twice the 8 W. Thus, rephrasing, be beware of water, each lovely year it kills many people (but not if the amount is one glass). Anyway, it is important to realize, the eyesight sees about 1% to 5% of real brightness, the sight says, oh its so dark, but it is damn bright at real. That is most dangerity. As well the excessive ozone in badly ventilated areas.
 

Audioguru again

Joined Oct 21, 2019
3,173
Marketplace show on TV yesterday exposed the UV disinfecting gadgets scam. The TV show measured how much bacteria and virus they destroyed. Most did almost nothing, even the very expensive ones.

To protect your eyes and skin, some of the gadgets were a bag with a "UV" lightbulb in it. Some used an ordinary lightbulb that produces no UV. You put your keys and cell phone in the bag and turn it on. Then only some surfaces of the items are exposed to the UV and get some bacteria and virus destroyed but there are millions that are not exposed. They do not say how many hours or days of exposure are needed. A wand also exposes only one side of an item to the light of UV and its distance is very important.

Some UV disinfectors produce UV-A and UV-B but not the important UV-C. Gullible people do not know the difference.
The TV show said that doctors say do not use this junk and use sanitizer liquid and hand washing instead.
 

Marc Sugrue

Joined Jan 19, 2018
213
Yes and No. If work is assumed hours then yes. If onlu one or two minutes are assumed, then dangerous power starts with about 1 kW, whilst the lamps in photo is twice the 8 W. Thus, rephrasing, be beware of water, each lovely year it kills many people (but not if the amount is one glass). Anyway, it is important to realize, the eyesight sees about 1% to 5% of real brightness, the sight says, oh its so dark, but it is damn bright at real. That is most dangerity. As well the excessive ozone in badly ventilated areas.
As i said in my previous post, If its true UV-C Its peak wavelength will be down near 250-270nm part of the electromagnetic spectrum - its radiation as opposed to light so you won't see it at all as the visible part of the electromagnitic spectrum starts at 380nm.

If your working on it, as a professional i can only give my advice and thats to wear relevant PPE as it can cause lasting skin damage and eye damage. A simple transparent polycarbonate visor or goggles will completely block UV-C so its very easy to mitigate against.

Most UV-C lamps don't cause significant Ozone unless they generate approx 180-220nm which is down near Vacuum UV so is not always a consideration, especially at lower power levels.

It is important to realise that the UV spectrum is made up of different bands which comes with varying levels of risk. And whilst your risk assement says its fine, other less knowledgable people may prefer to air on the side of caution. I'll stick to my assessment that its not safe to work on in close proximity without PPE and i'll let you make the same assessment.
 
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Thread Starter

Lectraplayer

Joined Jan 2, 2015
121
Although I know I can't see the UV-C, the gas discharge tube should at least be producing the blue glow as is shown here, shouldn't it? (In fact, this is actually the same type of CCFL tube in this device as in the wand, though my photo is poor.) Again, it is about the same size as an old laptop backlighting CCFL but bent into a U shape. ...and while we can't see anything above around 380nM, and UVC is below 300nM, most gasses produce multiple wavelengths. My research tells me that mercury is the most common for UVC gas discharge illumination, which it also produces wavelengths on down into the mid 400s and lower, which we can see. As such, I figure the presence of a blue glow would be an indicator of if I'm getting UV, which is the case with larger germicidal fluorescent lamps, though it does not necessarily indicate how much I am getting--usually reduced due to wear, which I don't have here.MVC-001F.JPG
 

Marc Sugrue

Joined Jan 19, 2018
213
Have you tried looking at yours with a digital camera? Digital devices have different sensitivity to the human eye so just because it shows light in a photograph doesn't mean you'll see it in real life. For example IR LEDs glow white under some digital cameras but you wouldn"t know it's on by looking at it. This may be the case here. I agree that some UV sources can generate visible spectrum but this is dependent on the chemistry used in the tube.
 
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