High power ultraviolet LED experiments

[@clivequinn8978]

The tip of the index finger is missing because that’s Clive’s capacitor discharge tool.

[@jvon3885]

So I started the video then skipped ahead after reading your post, and it literally landed on that exact moment.

[@AndrewJens]

I'm wondering if the actual tip of Clive's finger is from Temu?

[@Eremon1]

🤣

[@whitslack]

​​@@AndrewJensIt came in a handy 5-pack.

[@ralphj4012]

Clearly a deliberate removal, a smartphone operation modification, perhaps.

[@Eremon1]

3:37 "an extra layer of protection" missing a finger on the glove. 😆Never change Clive! Your humor brightens my day often. Cheers.

[@robinbrowne5419]

Me too :-)

[@keithking1985]

Yes Clive, never change... 👍🇮🇪🙏

[@tortureborn]

"At this point you could skip to the end and see the results." No way! Great video!

[@harrysmbdgs]

When curing UV resin, I’ve found less intensity for a longer duration gives a nicer finish. It results in less heating and therefore less stress / deformation as it cures. A gradual increase in intensity as it cures seems ideal. Although it can be blasted quickly if it’s something which doesn’t require a nice finish! 🤓

[@christopherleubner6633]

Can confirm it cures shinier, also a shorter wavelength helps cure it more uniformly 365nm is the best, but 395 would be good for thicker resins.

[@herrkulor3771]

Yes, the shorter the wavelength is better for surface cure. For surface curing, Oxygen hinders surface cure. "Oxygen inhibition"

[@harrysmbdgs]

That’s also very good to know, thanks!

[@keithking1985]

Like making custard. 😅 To much heat😮 and it's wrecked 😅

[@davelowets]

Yep. It's akin to having a paint booth temperature up too high when curing the paint. If the uv resin cures too fast, the surface of it can cure before the rest of it underneath does, and when the rest of it cures, it can shrink up the surface and leave a less than desirable finish.

[@Hazzard2theworld911]

Thanks, Clive. I’ve learned so much from you over the years; your manner of teaching is what I wish I had in school all along.

[@robinbrowne5419]

Me too :-)

[@keithking1985]

I would have loved to have had a teacher as good as Clive(and others here on KZbin) wish I learnt electronics when I was a kid... My life would have turned out brighter (pun intended)😅

[@KeritechElectronics]

Dubai'd pretty nicely, and the measurements clearly show a linear relationship between capacitance and power. Good work!

[@phils4634]

The great thing about using a capacitor dropper is the VERY low thermal dissipation. They don't get at all warm, and for the 50 or 60Hz mains frequency, the stresses on the dielectric are also pretty minimal. The only downside is the power factor, but for low power applications that's probably not a serious consideration.

[@davelowets]

I agree... the .5 P.F. is nothing to be concerned about with a few watts. 👍

[@gregorythomas333]

I've missed these kinds of experiment videos...not to mention the useful knowledge imparted :)

[@Jawst]

Amazing!!! Thankyou for your efforts!!! For the last few years I've been using 12 volt LEDs to help my tomato plants grow through febuary and March. this year I'm upgrading to the supercheap LED grow lights. I did a few grow tests with chili peppers, and I'm impressed with their results for the price!

[@tazz1669]

Thanks Clive, a very useful experiment, great idea to use the load capacitors

[@andy5974]

Thanks

[@bigclivedotcom]

Thanks. Much appreciated.

[@alexv3780]

You should create a decade capacitor box using standard values as steps instead of 1, 2, 3, etc, with discharge resistors across each capacitor and an on/off switch for preventing arcing will changing the capacitor. Maybe an extra push button in parallel with the on/off switch for fast testing? It will be an interesting project video!

[@DanBowkley]

While borrowing the decade box layout from the one Dave tore apart a couple months back

[@RODALCO2007]

Great experiment Clive. The 2 or 4 uF motor caps are excellent for the reduced power dissipation in the UV LED chips. Love the missing tip on your "safety glove".

[@joelmurphy9369]

Thanks Clive! I will always keep an extra layer of protection around if I need it.

[@lesmaybury793]

Excellent demo of the role capacitors have in dropping power. Often refered too but rarely seen like this. Cheers Clive 👍

[@tactileslut]

Air conditioners usually have two capacitors in the same can. They never fail together. I have a half dead one reducing the brightness of an incandescent four channel sparkle/chase light set on my house. 🎵 Making good use of the things that we find, things that the everyday folk leave behind. 🎵

[@d.t.4523]

A rotary switch for dimming sounds like a good idea. High low and off, like a box fan switch. Thanks, keep working.

[@michaelseitz8938]

I have LEDs from this company and the resistors under the silicone rubber were very easy to replace 😊

[@russellzauner]

I've been investigating UV LED for a while now; putting together a water purification rig that can support a few people while camping, so need some decent volume/flow but that limits the time the water is exposed if it's moving fast, etc, etc just another use case but having someone put all this tested data here is pretty great to use. Thanks man!

[@bigclivedotcom]

For water it will have to be UVC, and at this point in time the best source for water purification is still a quartz tube mercury vapour version.

[@PaulSteMarie]

I wonder what they are doing to those flip chips to permit soldering? When i took a semiconductor lab in college, we had a special weird solder, indium based IIRC, to solder to silicon, and it was a right royal 5 star PITA to get it to wet the surface. It was a lot easier to use the special probes that just mashed into the surface with a rack& pinion setup similar to a microscope.

[@bigclivedotcom]

I think the LEDs have a metalised layer on the base for the connections.

[@DmitryKiktenko]

My play with such LEDs succeed by resoldering a current control resistor to shift down power and add a capacitor after rectifier to get rid of flickering. For white 4000k leds it is a great solution! Low heat, no fan needed, long life, no flickering, hotter light temp (makes 3000k from 4000k). Ideal!

[@leesherrington6337]

Can't wait for you to upload your videos Clive, you're a legend!!!

[@StaticCamperVan]

Clive, I would never skip ahead on any of your videos. It's all interesting. Plus I was hoping to get a little suntan while watching.

[@phonotical]

I had one of these a long while back I thought wow how brilliant is that, then I remembered how thin my curtains are, and it must seem like I've started a grow lab 🙈 so rather than be raided at 3am I decided it would stay off and look pretty instead 😂

[@TomTRobot]

Apparently UV curing is basically a matter of proportion of t*W/cm2. Reducing power to increase longevity would either increase time and/or require changing distance, both of which may be acceptable trade-offs depending on the application. Given that there are are exponential decreases in longevity with high junction temperature you could get a lot of bang-for-the-buck tuning the power usage of these devices rather than investing in cooling solutions.

[@levieux1137]

In order to optimize heat dissipation and operating life, it's still better to run the LEDs at a lower *peak* current. Series capacitors only reduce the average current and do not reach the same efficiency. For reference in my office at work I tried multiple LED blocks like your yellow one: 50,40,30 and 20W. They were all exactly the same with a different number of regulators soldered on them, so all that changes is the current through the LED. The 50W one lasted one week, the 40W one month, the 30W ~6 months and the 20W is still working fine after 3 years. And the luminous power is not that far from the 50W one, probably about 2/3 of it. So the best way to achieve optimal efficiency with LEDs is just to buy the lowest power modules of the same family and install several of them in parallel if needed.

[@abitofabitofabit4404]

LM358? An op amp, a voltage source, a MOSFET, and a resistor are enough to make a current sink; an inductor, a diode, and some positive feedback added to that makes a hysteretic converter. I for one wouldn't mind seeing the teardown.

[@LoftechUK]

At 4UF is even half its full power so it will last years more. Great video.

[@frankowalker4662]

Cheers Clive. Interesting results and well worth taking note of.

[@radio-ged4626]

I've recently fitted a capacitive dropper circuit to a valve heater chain in a Bush DAC90A radio I have. So only a small portion of the original dropper resistor is used to feed the rectifier valve anode. The resistor is now running cold and the heaters are at around 5.6v AC - a little lower than they should be but with no or little detriment to performance. I'm using a 10 Ohms 1 watt inrush resistor and a 100K 1 Watt discharge resistor across the 1.5uF 400V AC rated motor capacitor. Using phase-shift to reduce power output rocks, my wireless now no longer smells of hot dropper resistor and the case isn't being slowly cooked.

[@charliesoffer]

I'm a great fan of DAC 90A radios and have a fine collection. Really looking forward to trying your dropper idea! Thanks.

[@Vokabre]

If you read УХО in Russian Cyrillic it means "EAR", can't unsee it as soon as I noticed the logo.

[@TATICMOOR]

Great test, Clive. I'm glad to have not skipped to the results when there was a chance you got zapped, but the small crack was sufficient with the screwdriver. I am evil, yes I am, lol.

[@G1ZQCArtwork]

I tested a Motor Capacitor with my insulation tester set at 250 v, then discharged it at arms length with a screwdriver, what a loud bang it made, I chickened out trying it at 500v or 1,000v, as I thought it might shoot off and break something.

[@NinoJoel]

It's also not so healthy for the caps

[@jimsvideos7201]

Great fun Clive. Now I'm curious to see if there are similar 365 nm parts available...

[@GothGuy885]

"Violet is turning Violet !!! " willy Wonka:" Don't worry ,its just big Clive doing an experiment with a high power U.V LED nearby..... Thanks Clive, this info is good to know! 😀👍

[@shadetreemechanicracing22]

We're going to test that.

[@uktay001]

Nice explanation as always Clive 👍

[@TechGorilla1987]

Clive goes all "Prudence The Safety Goat" with the gloves. Also Clive: puts on gloves that are missing a finger. That's why I watch.

[@David5467]

Hi Clive. What do your bank notes look like under a UV light? would be interesting to see.

[@bigclivedotcom]

They have quite interesting patterns.

[@David5467]

@@bigclivedotcom So did the ones in New Zealand before they changed to plastic notes here. now they just have a square with the note value on them . but have never seen a UK note under a black light.

[@KarldorisLambley]

i have loved UV since attending a pantomime some 40 years ago. they did the thing where the lights went off, and a UV light flickered on and off so the 'skeletons' on stage appeared to run about madly fast. i seem to recall Christopher lilicrap was in it, and he sang a song about making 'a proper cup of coffee in a proper copper coffee pot'.

[@bigclivedotcom]

I had a similar UV skeleton experience at a pantomime at the King's Theatre in Glasgow when I was a kid.

[@TDOBrandano]

The way to align those tiny chips on the solder pads would be to use a dedicated pick and place machine, but if I had to do it manually I'd use a stack of two photo-etched masks. One to provide spacing and avoid disturbing the solder paste, the other closely fitting the chips so they could be dropped in with small tweezers. Potentially a third one above this could provide guiding channels to slide the part on.

[@getyerspn]

Now that's a good coincidence , yesterday I ordered that exact dob led board from AliExpress... I suspect I'll be adding a motor cap now...👍

[@charliesoffer]

That's one heck of a SAD lamp, Clive! Mandatory sun screen and shades must be worn though... 😊

[@mevk1]

This knob is wondering if adding an inductor would be practical way to increase power factor. If so maybe you could follow up with video by experimenting with some inductors you have laying around?

[@Ed19601]

You know things get serious when Clive brings out the gloves

[@geoffgeoff143]

Would love an update on UV C LEDs and UV C plus.

[@jhsevs]

5:38 I really like that fake pink Wago. I’ve been wanting to buy fake Wagos for years, but I’ve postponed it because I really don’t want ones that are in the original color, in the fear of mixing them together with the real ones that I use for proper stuff. What do you search for to find pink ones cheaply? Just add "pink" to the search term?

[@shaiseg]

perhaps the reason the capacitors did not hold much charge because they are connected in series with the leds, hence they hold low voltage?

[@bigclivedotcom]

The meter will have provided a slight current shunt in combination with the circuit's low current drain.

[@WouterWeggelaar]

I am using these LEDs for developing cyanotype photography, and I bought these about a year ago. Bought 4, using one so far to expose cyanotype coated papers. Now with these capacitor hacks, I might have to start messing with the LED (which I planned for any way hence purchasing a few!) I did also ground the heat sink to be extra sure

[@ChindoCaine]

I wonder if I missed a video at some point - did the good old HOPI meter die or why do we get the AnTai lately? Or is it just because it has a "FUN" button? 😂

[@andyreact]

He has had it a while, it is better at low power ratings, and the display is less flickery on camera.

[@Stuart-AJC]

And a "Frequence" measurement 🙂

[@stepheneyles2198]

I'm wondering what happens when you press the FUN button!

[@alexhajnal107]

@@stepheneyles2198 Clive did a video on one in a pub in Glasgow. "Delmonicas mystery toilet button"

[@NinoJoel]

​@@stepheneyles2198dam... Now I'm curious😂

[@Dinco422]

Awesome experiment and useful too :)

[@wisher21uk]

Excellent experiment Clive nice results thank you 😊

[@Psyden5757]

i actually have one of these, but with a pink light meant for growing plants i modified mine by removing the ptc and placing a 10k pot in it's place, that regulates the brightness really well without having to get a dimmer or finding a suitable capacitor

[@SumNumber]

Make some with your config and sell them on the side . It could mean extra Guinness of the shelf ! You may have started a fashion craze with the gloves . One must be careful about such things . Thanks for the share . :O)

[@Graham_Langley]

That's got me thinking about mounting one to light the street outside for Halloween.

[@gertbenade3082]

Instant "like' the moment I saw High Power and UV in the same sentence! Now, on to watch the video! Thanks Clive - I just KNOW this one will contain a reference to a Death Beam(tm) of some sorts...🤣 A good video! I can extend the life of my LED grow ligths this way...

[@SirBoden]

At that scale surface tension is a usable force.

[@jonleiend1381]

I used to use gloves just like that all of the time for 120 VAC work all of the time.

[@dcallan812]

Interesting light driven at a lower input will save the LEDs frying. I would love to see just how they make both the bear LEDs and solder them to a board. (your cue to fly to China 🤣🤣) See you Thursdays Live Patron. 2x👍

[@davelowets]

Something like a 5 or 6 position rotary switch and a hand full of caps would make a very simple crude dimmer for these.

[@FLomasterZ]

Something changed in your microphone. I can hear metalic noise now.

[@davelowets]

Boy, the manufacturer of that LED COB must REALLY have their reflow profile down to exacting specs and tight control to be able to produce those flip-chip COB's without having a ton of "tombstoned" or crooked LEDs that are only contacting one of the pads. It's amazing what the surface tension of liquid solder will do to a tiny part like those individual LEDs if only one of the solder pads has it's solder paste melt first. The reflow profile MUST be so closely controlled so that ALL of the solder paste turns to liquid at the very same time. Back in the day when we didn't have such precise control available, the SMD parts were glued to the board with tiny glue dots placed by a machine before the pick and place machine put the parts on the board. I can't imagine that those tiny LEDs are even able to be glued down. It sure has to be hard to control the reflow process with today's lead free solder too... 😬

[@capitalinventor4823]

All of the resin for 3D printing that I've seen, that is for the hobbyist, states that it cures using 405 nm UV light so that's what I thought the printers and curing stations were using.

[@user-mo5hz9kp6y]

Now Clive goes into work wearing a sunburnt face with a hand shaped white spot.

[@ericthecyclist]

I have one of the 70W light chips but blue-green for growing (just spring seedlings in my case), but it produces too much heat, even mounted to a big aluminum tube and using a diode to cut out half the cycle. I never thought of using a capacitor to limit the power, despite seeing a bunch of circuits doing it that you displayed. Wonder what higher voltage capacitors I've got kicking around.

[@vikenemesh]

02:50, Oh no, what happened to the good old Hopi?

[@bigclivedotcom]

Still here.

[@gwc1410]

Very good experiment. More like this would be nice. Do you have any idea if the supposed 395 nm wavelength is harmful to the eyes?

[@bigclivedotcom]

The extreme ends of the spectrum pose a risk to eyes because they are seen as a "dark" colour and the eyes don't react as they would to white or green.

[@markfergerson2145]

Did you notice Clive’s fingernails glowing at 8:23 when he added the 220 nF capacitor? Any wavelength that excites fluorescence in biological materials like that is hazardous to the eyes at the very least. Shorter wavelengths can literally burn skin as I’m sure you know but longer wavelengths are still nothing to trifle with. I have still never gotten over UV making nails and teeth glow. Very cool, but any anomaly like that should make you extra cautious.

[@MadScientist267]

​@@markfergerson2145Intensity is everything

[@drkastenbrot]

UVA is not yet a major risk but you want to avoid looking into it because our eyes dont see it very well. it is much brighter than you can see so you dont have the natural reflex of squinting and adjusting the iris.

[@drkastenbrot]

White leds generally use 450nm leds and a varying phosphor composition and density for color temperature. I have not seen any white leds with 395nm chips.

[@d614gakadoug9]

Some LED streetlights may use the shorter wavelength emitters. Phosphor failure (apparently detachment, but I've only seen some very simplistic explanations) results in quite distinctly purple lights.

[@DUKE_of_RAMBLE]

I have gloves like that for cleaning fish at the cabin (grey glove with blue coating), and even while dry, they allowed touchscreen use. _(modern smartphones, so capacitive; I don't own anything with resistive touch)_

[@denisohbrien]

seems to depend on the brand, im a mechanic so generally buy in bulk and simply buy from whosoever selling 120 pairs for cheapest on ebay or that. some work absolutely fine with a phone, some dont, in the latter case simply using your knuckle seems to do the job.

[@DUKE_of_RAMBLE]

@@denisohbrien haha Yes... I've done the knuckle trick as well! Albeit for different reasons, as the palm side was slathered in fish slime... 🥴

[@madmancrow7659]

😊 as always, it is very fascinating

[@jvon3885]

As a novice electrical engineer wanabe, this was a nice video and helped me understand something that was seemingly complicated prior. Anyways, i need that handy tool you got there. I type too fast on this small keyboard....Fixed grammatical errors.

[@MrZANE42]

It looks like it's flickering a lot when you add the capacitors, especially the lower values. I realize that might not be visible without the camera and since you wouldn't use this to light up a room or work area it might not matter, just wanted to put it out there.

[@bigclivedotcom]

There's no smoothing even at full power. The camera is picking up the slight shimmer.

[@mrrkrr]

Only the best videos start out with "I have a purple LED..." 😁

[@-r-495]

3M sells good safety glasses that will protect you from that light. It may leave you with yellowish spots all over if you get too high of an exposure. I‘m interested in these LEDs but am looking for ones under 300nm.

[@activelow9297]

395nm is my favorite nm. Love that deep purple glow. I light up my entire house with it.

[@4lecsg]

For this to work, the LED board needs to be somewhat decent quality. I tried to limit a very cheap led projector like this, and it ended up powering only a quarter of the LEDs on the board, and it still failed after a year while also lowering the light output.

[@Buildonsound]

even I had to look away jesus thats bright.

[@Dinco422]

4:58 "that is making everything in the room glow" lol... wink wink xD

[@Chris_Grossman]

A nice experiment!

[@zh84]

Is there a formula for the lifetime of an LED compared to the current through it? I remember reading that the lifetime of an incandescent filament is proportional to the fourth power of the temperature, which is why "long life" bulbs that use a resistor to burn very dimly can last for decades. If the same applies to LEDs, running that array at 0.6W instead of 45W would mean that for every second of the original lifetime, it would last a year!

[@abitofabitofabit4404]

It's generally true that a 10C reduction in junction temperature doubles the operating life of the component. Adequate thermal management is crucial for power LEDs, and a common corner to cut.

[@petehiggins33]

@@abitofabitofabit4404 This is correct and it highlights the fact that it's not the current that determines the life, it's the temperature of the chip. So the heatsink used is just as important as the current level.

[@dean5263]

Thanks.

[@Zlodej5]

Your standard capacitor does not need a discharge on its intended use as the fan or motor windings have far lower resistance then the resistor would and will provide the discharge. I am surprised you don't have the spade (or whatever it is called) crimps to banana cables. they are really handy when experimenting with mains inventions, as means of connecting common rocker switches inside multiple stages, or neon indicators when working within mains voltage

[@stevenlarsen1875]

Switching between the capacitors would make a great dimmable led?

[@marcellipovsky8222]

A lot of great FAFO in today's video.

[@vsvnrg3263]

bit of trivia. when i got my little uv torch i went around checking what glowed. i was surprised to find that most of my 40 year old green hitachi power tools came alive. i have to wonder why they put such ingredients in the plastic when they made them.

[@Pleyer7575lol]

Why is there a 'fun' button on the killawatt

[@julianward5436]

Can you experiment with some narrow band uvb leds for the vitiligo homies out there?

[@bigclivedotcom]

I'm not sure how easy those are to get.

[@davidfalconer8913]

As mentioned in previous comments ... the CPC 2μF capacitor is IDEAL for those wanting to make an ( everlasting ! ) nightlight using a 230 Volt , 60 Watt " squirrel cage " Tungsten filament bulb ( our Poundland™ seems to have sold out ? ) .... but this lamp will then last longer than you do ( ? ) ... ( tried - n - tested ) ....... DAVE™🛑

[@Slikx666]

Clive. Given you said LEDs you've reminded me that I was going to send you a link to a video that is making LEDs. You'll find it interesting. 😄👍

[@FirstLastOne]

Those 395nm voilet UV LEDs actually yellowed white plastics as I sadly discovered on a couple of my PCs. This now begs the question, what is the actual UV spectrum that it ranges and is prolonged exposure to these violet UV LEDs safe? I have noticed that my summer tan lasts well into January ever since installing those violet UV LED in my PC next to me on my bench.

[@bigclivedotcom]

The Philips facial tanning units use UVA tubes.

[@grumpy2.0]

I wear the touchscreen version of those gloves. With all the finger tips

[@shadowtheimpure]

I am now going to use THIS video every time I need to explain the concept of a current limiting capacitor to someone.

[@twocvbloke]

Only drawback is the lack of smoothing on the LED module itself, driving people nuts who can see that flicker, though on the plus side, it coul dbe a good deterrent as part of a purple burglar alarm............ :P

[@Leo99929]

Interesting power drop with the caps. I wonder about other applications? Like I have some 240VAC resistive silicone heater pads that get worryingly hot in use. I've put in a resettable thermal fuse, to limit the temp, but I'd like to lower the power to make them last longer. I was thinking of halving the string and putting the two halves in series to halve the power. I guess this cap method would reduce the power too much? The full set is over 1kW, from memory.

[@d614gakadoug9]

At that power level a capacitive dropper isn't very practical. Phase angle control with an SCR "dimmer" is probably the most practical and least expensive if you can tolerate the possible RFI (which can be substantially reduced with a relatively small inductor). If you want nice sinewave power, you can use an iron-core transformer as a bucking autotransformer. You would need a secondary current rating of around 4 to 5 amperes (power for the heaters divided by line voltage) and a primary voltage rating equal to your line voltage. You connect the secondary so that its phase is opposite that of the line - it "bucks" the line voltage. e.g. a 12 V secondary would reduce the 240 V to 228 V. which would reduce the power in the heaters by about 10%. Remember that power in a resistor is proportional to the square of the applied voltage.

[@4aneme8R]

I used a great deal of UV in nondestructive testing, despite glasses with UV filter I am headed for cataract surgery.

[@d614gakadoug9]

You may just be unlucky. I have plastic eyes now. They are a semi-failure in that they were supposed to give some degree of accommodation (ability to focus) but I've wound up with absolutely fixed focus. Still, I'd be blind without, but I spent a lot of money for the "premium" implants and got no added benefit.

[@alnicospeaker]

Usually I modify these AC COBS with two parallel 1µF X-type as a dropper C and 25µF 400V electrolytic across the + and - of the FBR make these mostly flicker free and not run hot with basic cooling. It's quite hard to get a good solder connection tho - even with all silicone carefully scraped off.

[@athreedognight4022]

Too cool, as well.

[@maicod]

That Antai looks surprisingly similar to the Hopi, is the Hopi dead or just worse (the flickering) ?

[@bigclivedotcom]

Just a different accuracy at lower power levels.

[@HB-ps6rn]

These LEDs are also used inside the cheaper LCD resin printers as the main light source for the LCD. They tend to be much less reliable than SLA or DLP printers but are much cheaper.

[@Kerbtree]

If you want to make touchpad-enabled rubber gloves, you can get conductive yarn.

[@gowdsake7103]

Chip shooters when I worked on them were plus minus 60 microns placing at 16 a second