High power ultraviolet LED experiments

Summary

The script describes experiments conducted with a high-power 395nm purple LED purchased for UV curing applications. Various capacitors are placed in series with the LED to observe the effect on light output and power. Initial power is 45W. A 100nF capacitor drops this to 0.6W with visibly dim output. Larger capacitors proportionally increase brightness and power, up to 5.9W with 1μF. Motor run capacitors of 2mF and 4mF further limit power to 11.5W and 23W respectively while maintaining useful brightness, potentially increasing LED life by reducing heat.

Takeaways

• 😀 The video covers experiments on controlling the brightness of a 395nm purple LED using capacitors
• 😎 The goal is to reduce LED power to extend its life while still emitting useful UV light
• 💡 The stock LED draws 45W at full power
• 🔋 Adding a 100nF capacitor drops power to 0.6W
• 🔋 A 220nF capacitor allows 1.3W, and 330nF allows 1.9W
• 🔋 Larger capacitors continue to increase power, with 1μF yielding 5.9W
• 🤔 Motor run capacitors allow even more control of LED power and light output
• ⚡ A 2mF motor capacitor runs the LED at 11.5W
• ⚡ A 4mF capacitor runs it at 24W, halving the stock power
• 💡 The experiments show capacitors can easily control LED power and life versus output

Q & A

What type of LED is being experimented with?

A 395nm wavelength (deep violet) high power 50 watt UV LED module intended for 3D printer resin curing.

How is the LED module powered and current regulated?

It uses a mosfet and l1015 chip to regulate drive current instead of multiple linear current regulator chips.

Why use flip chip LEDs in the module?

Flip chip LEDs connect directly to pads on the surface so don't need wire bonds, allowing for compact size.

What capacitance values were tested in series?

100nF, 220nF, 330nF, 470nF, 1μF, 2μF and 4μF motor run capacitors.

How did adding capacitors in series impact brightness and power?

Increasing capacitance increased brightness and power up to about half rating, extending LED life by reducing drive level.

What was the no-load power draw of the LED module?

45 watts initially with no series capacitors.

What safety precautions were taken?

Wearing insulating gloves when handling powered connections.

How can the capacitors be safely discharged after testing?

By shorting leads with insulated handles and checking voltage decays to safe level.

What benefits did the testing show?

That LED brightness and power can be easily adjusted for specific applications by adding series capacitors.

What ideas did the experiments give for future work?

Building the LED and capacitors into a case to make a adjustable output UV curing light.

Outlines

00:00

😮 Experimenting with a high-power purple LED

The first paragraph describes obtaining a 50W 395nm purple LED and performing initial experiments. Power measurements are taken with no capacitor, then with capacitors from 100nF to 1μF in series to reduce brightness and power for LED longevity while maintaining some useful output.

05:00

👷‍♂️ Further reducing LED power with larger capacitors

The second paragraph continues the experiments using even larger capacitors salvaged from motors. A 2mF capacitor reduces power to 11.5W. A 4mF capacitor cuts the power in half to around 24W, which is still a useful brightness but will greatly extend the LED lifespan.

10:03

💡 Using capacitors to tame LEDs simply for longevity

The third paragraph concludes that series capacitors provide a simple way to tame down high-power LEDs to improve lifespan while maintaining decent brightness. Interest is expressed in further developing this into an enclosure to test long term usage.

15:05

😊 Brief closing statement

The fourth paragraph provides a brief closing statement summarizing that series capacitors can prolong the life of an ultraviolet or white high-power LED in a simple way.

Keywords

💡Purple LED

The video focuses on experiments with a high-power 395nm purple LED, likely intended for 3D printer resin curing. This specific color LED is key as its output is very close to ultraviolet wavelengths useful for curing.

💡Linear current regulation

Unlike similar LEDs that use parallel current regulator chips, this LED uses a MOSFET driven by an unknown chip (possibly L1015 or 358K10) for linear current regulation to achieve consistent LED brightness.

💡Flip chips

The LED uses flip chip bonding where the LED die are directly soldered to pads on the circuit board with no bonding wires. Allows for very compact LED assembly.

💡Capacitors in series

A key experiment in the video is placing different capacitors in series with the LEDs to limit current, tame the brightness and possibly extend LED life by underpowering.

💡Power output

Throughout the experiments, the wattage output of the LED assembly is measured when using capacitors ranging from 100nF to 4mF. Allows determining optimal capacitance for output.

💡Discharge resistors

Safety concern mentioned about whether the capacitors have internal discharge resistors to avoid shock risk after being powered.

💡Motor run capacitors

Higher capacitance motor start/run capacitors pulled from appliances are tested in series as well to further limit current.

💡Ultraviolet effect

Even when powered below the rated 50W with added capacitors, the video shows there is still a clear glow showing the purple LEDs can emit noticeable UV.

💡Prolong LED life

Primary motivation for the experiments is determining simple ways to lower the LED drive power that will likely extend the usable lifespan of the LED components.

💡LED fixtures

The video speculates these specific purple LED assemblies may be intended as drop-in replacements for existing LED fixtures, thanks to matching size and mounting.

Highlights

Experiments with a 395nm purple LED to see effect of adding capacitors in series

45W power consumption with no capacitor

0.6W with 100nF capacitor

1.3W with 220nF capacitor

1.9W with 330nF capacitor

2.7W with 470nF capacitor

5.9W with 1μF capacitor

11.5W with 2μF motor run capacitor

24W with 4μF motor run capacitor, effectively half the LED's original power

LED chips placed directly onto PCB without wire bonds

Constant current regulation done with MOSFET instead of linear regulator ICs

Taming down LED power extends lifetime significantly

Interesting simple way to reduce LED power using common motor run capacitors

Should add capacitor inside LED fixture for clean integration

Useful experiments to characterize LED behavior with different capacitors

Transcripts

I have a purple LED let's experiment

shall we and do lots of experiments with

it so this came from

AliExpress it is branded yxo Yuen now

220 volt 50 wat it's probably going to

be available in lower voles as well high

power UV purple LED 395 NM for basically

for printer curing this 3D resin

curing and I get the feel out this is

sold for getting existing uh 50 W LED

fixtures and basically taking the

original white LED out and putting in

the ultraviolet one instead and the

ultraviolet one will I say ultraviolet

it's deep violet at 5 395 NM H it um is

probably just the beer chips that nor be

used to excite warm white phosphor but

it's a nice color very nice color that's

one of the reasons I got it now if we

take a closer look at the

chip and I'll Zoom down

this

if we take a closer look at that we can

see the incoming power here we've got a

metal oxide veror we've got a brid re

fire we've got the LEDs wir as a large

series string of parallel pairs that

basic down here go up again down here go

up and just zigzag all the way until

they get to the end but unlike other uh

high power LEDs that have the simple

rectifier and then they've got loads of

linear current regulator chips stacked

in parallel this one has a mosfet a 4

n65 a 4K and it's driven by the very

mysterious l1015 or 358 K10 and this

chip is doing the linear current

regulation with a high power mosfet so

you set the current sensing presumably

with a couple of resistors under here uh

and it will then regulate the power

through the LEDs I wonder why they're

doing

that um I was going to dig this out but

I thought I'll just rack it if for do

that let's do the experiments first if

we take a closer look at the chip though

we can see that it uses uh the flip

chips flip chips are LEDs that don't

have the wire Bonds on them going to the

adjacent pads they literally have tiny

little bare copper pads with the a blob

of solder in each and then they place

the chips onto the sort of the soda

paste and it's the bare LED chip itself

no case that just the bare chip

literally flows on like a component

they're tiny I wonder how they get it so

accurate or maybe that is why they've

got these large areas to reduce accuracy

because the chip will kind of Lan itself

as it melts anyway what I'm going to do

is I am going to bring in the

LED and I'm also going to bring in a

notepad because I have some capacitors

to put in seies with this let's Zoom

back out again a bit cuz I'm going to be

bringing the

anti here is the

anti and we'll hook it up to this and uh

since I'm going to be picking this up

and pointing at things I'm going to put

a pair of gloves on as an electrical

safety measure rare but true so first of

all I'm going to start by sticking these

wires in here they're just push in

should push in they are pushing in and

if you want to release them you uh use a

gently rounded item and you push down in

these while pulling the wire gently and

it should just pop out so if I pop this

in here we're going to be swamped with

ultrav well near Ultra out light very

shortly I'm going to stuff those in

there but I am going to put the gloves

on just generic plastic dipped gloves

because uh when you're working with

electricity it helps to just have an

extra layer of protection personally I

don't feel I need to at this bench

during this experiment but I'm going to

do it because I feel it is important to

demonstrate and also I would normally

recommend that the heat sinks these are

mounted on actually have um a ground on

them because these uh circuits are a

tiny thin shim of fiberglass the tip of

the finger is missing just for the touch

pad boop boop boop just to get you know

stuff done uh other things worth noting

this is a solid state relay heat sink

it's just one that I had to hand and the

holes on it for the solid state really

are exactly identical for the diagonal

spacing of the LED that's very handy

right to what it's about to get very

piple and I shall plug this in it's very

purple I'm going to Shield myself now

look how purple it is it's Mega purple

and it

says everything's lit up in the fac I've

got a hat here just basically to uh to

test it with and it's just basically

it's it's making everything glow I don't

want to look directly into that too much

um I can also feel the heat from it uh

89 power factor 44.9 wat so let's say 45

wats and we'll fill in the first value

45 watts and then we'll put LEDs in the

series and see what we get that does not

look bright looking at it I'm going to

point it over there oh that is making

everything in the room glow yes that is

very bright right tell you what I'm ping

off

now and then we'll put the first

capacitor in line and this is going to

be a 100 Nar capacitor I zoomed right

out here I shall zoom out a little bit

more

so technically speaking this is live and

that's neutral so tell you what I'll put

them in the correct slot just for the

picky people actually I'll put this one

in here and I'll put a capacitor in

series let's dig out the capacitors I've

marked them all up a very small 100

nanard capacitor I'm going to put this

one

um into a

Chinese clone wigo style connector

straighten that wire up shove it in

there click it down put it into the 100

Nano

capacitor what do you reckon the power

is going to be from this with 100

nanopar in line with

it are we

ready let's power up it's very dim I

mean it's not bright at all it

says 6 watt5 power factor uh 0.6 wat

that's really very low still useful hold

on I'm just going to do a scientific

test to going to turn the light off I'm

going to take the exposure

off I'm going to get the baseball cap

and I'm going to point this at it you

know it's not bad you know for for about

half a watt that's really not bad is it

okay tell you what I'm going to pause a

moment Charlie while I bring the light

back so you're about to get dazzled the

light one moment

please the light is back uh let's unplug

this let's discharge that capacitor so I

didn't get a little tingle off itth what

have I got to discharge that with hold

on just give give us a second do I have

a there's a screwdriver there's a uh

security

screwdriver not much of a spark off that

good having said that uh it's intill in

circuit with this so that LA to like a

discharge

resistor and I've disconnected the wrong

thing anyway so let's put that wire in

there and we'll stick the 220 n f in I

would expect that to be round about one

watt

perhaps so

here is a 220 n f

capacitor we'll pop that in

here this is kind of just really

experimenting to see what sort of power

levels you could get you know if you

wanted to just tame it down a bit

because under running these LEDs

significantly like say running at 10

wats instead of the 50 wats it's going

to make it last for ages but still put

out a useful amount of energy 220 nart

it's visibly brighter already it's 1 to

7 do we say 1.3 let's say

1.3 watt per factor5 again okay because

there is the capacitor limiting it and

again I don't think I even need to

um you can see the flicker there because

it is basically it's not smooth but I

can't see the flicker but it's put out a

decent amount it's actually doing yeah

that's actually not bad one what's

surprisingly good for that deep violet a

good ultraviolet effect but not Mega

let's unplug

it next

capacitor is going to

be I think this will be self-

discharging actually you know what let's

just uh shun it

anyway it's self- discharging that's

fine

um but I'll I'll play sa and discharge

them anyway let's put the 330 Nano this

is a huge 330 Nano for

capacitor

this is where if your board just

watching me do this you could just

basically jump to the end and see the

results it's your call 330 n looking a

lot brighter it's now let's say

1.9 5 I'd say that's close to 1.9 watt

okay 1.9 Watts it is could just say 2

Watts I'm going to say 1.9 wats and that

is going to be very visibly bright yeah

I can see it glowing even in the studio

lighting I can see where you can see the

Shimmer off it just at the side that's

very good

unplug unleash capacitor shunt capacitor

anyway and we're on to 470 nard

now which is an unusually small

capacitor just depends on the

manufacturer and construction the Varian

size quite a lot uh 47 n farad brighter

again looking pretty good in the making

this pop this hat it's very

visible

uh 2.7

Watts okay and then actually I'm just

going to unplug this like this right

just to show you that it does hold a

charge if you

don't and it just made a mockery of Me

by not making a l crack noise oh okay I

just plug unplugged it at the zero

crossing point then

excellent to try dabbing that across

let's go to uh let's plug unplug this

this time and let's go to one microfi

this time which I would expect to be

about 5 wats then based on what we've

done so

far so let's plug it in at that I might

even parallel two

up very that's actually making the hot

light off camera that's pretty good

um it's 6 wats 5 well 5.9 let's call it

5.9 Watts so actually it doesn't take to

much capacitance I'd kind of like to get

a 2.2 megard capacitor wonder if I've

got one H I shall go and look for that

one moment

please I did not find the capacitors I

was looking for but I did find some

motor uh run capacitors let's cut these

open let's rip them over and pop them

out these are from CPC in the UK and

this one is rated 4 microfi which would

be

about 4 microfi should be about 24 wat

shouldn't it theoretically at this rate

could this be an interesting way to tame

them down just use motor capacitors and

this one is 2 Mard so it's going to tame

it down to about 12 wats theoretically

let's find

out I wonder if these have a discharge

resistor I don't think they've got a

discharge resistor and this is uh Shady

cuz these will deliver quite a bang Okie

doie I shall test that so I shall get a

bit of wire here this will

do and I shall get this

wi and hook it around one terminal like

this just temporary

connection and the other wire shall be

hooked around the terminal

like this again a temperary

connection and let's see what happens if

I stuff this into this terminal here and

plug it in what are we going to guess so

this is 2 Mard motor

capacitor what you Reon is it going to

be 12 wats let's find

out the power is

11.5 wat

11.5 wats that is actually starting to

get a very useful level of ultra violet

while also extend the life and you could

fit this capacitor in the case now to

test this if this has a discharge

capacitor resistor should I say I'm

going to short it out but I'm going to

uh basically just disconnect it from

here first do not do what I am doing and

that should have left a charge on if

there is a hold on there was a bit of a

pop there not

much I shall test it I I'll make a note

Down Below in the description if there

is h a discharge resistor in these I'll

disconnect them and just see the voltage

goes down at a modest rate so let's get

the next connect C

on so this is the four micard and that

is theoretically going to run the LED

somewhere around kind of half its rating

that' be quite

useful and these motor capacitors are

very common and you don't have to worry

about them going short circuit cuz the

worst case happening uh if they went

short circuit is the LED would just go

up to full brightness so I should pop

this in here place your bats what's it

going to be with for Mard very bright

it's going to be that's really making

everything light now and it's 23 Watts

so that's effectively rendered it 4

microfarad I'm shiing my aate here equal

uh let's say 20 it's 23.7 let's say 24

wats that's

interesting uh that's going to half the

power dissipation from this led oh I

didn't check the power factor hold on

let me just check that fiveish 58 yeah

that's what I'd

expect so all worth doing those

experiments they were interesting I

should just discharge

capacitor it should have been discharged

because of the uh it was in circuit with

that but there we have it uh the ultrav

Viet LED dubing it with capacitors here

are the end

results very easy to tame it down and in

a suitable fixture uh that would just be

a great way of getting a long lasting

LED that still put out fairly decent

power but the LED chips would last a lot

longer so that was a that was a good

experiment that was well worth doing

kind of want to build that into a case

now with the uh with an actual capacitor

just to see how that uh how that works

but there we have it uh dub being an

UltraViolet or a white LED just for

prolonging LED life in a very simple

way