High power ultraviolet LED experiments
Summary
TLDRThe 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 1ฮผF. 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
- ๐ The video covers experiments on controlling the brightness of a 395nm purple LED using capacitors
- ๐ The goal is to reduce LED power to extend its life while still emitting useful UV light
- ๐ก The stock LED draws 45W at full power
- ๐ Adding a 100nF capacitor drops power to 0.6W
- ๐ A 220nF capacitor allows 1.3W, and 330nF allows 1.9W
- ๐ Larger capacitors continue to increase power, with 1ฮผF yielding 5.9W
- ๐ค Motor run capacitors allow even more control of LED power and light output
- โก A 2mF motor capacitor runs the LED at 11.5W
- โก A 4mF capacitor runs it at 24W, halving the stock power
- ๐ก 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, 1ฮผF, 2ฮผF and 4ฮผF 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
๐ฎ 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 1ฮผF in series to reduce brightness and power for LED longevity while maintaining some useful output.
๐ทโโ๏ธ 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.
๐ก 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.
๐ 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.
Mindmap
Keywords
๐กPurple LED
๐กLinear current regulation
๐กFlip chips
๐กCapacitors in series
๐กPower output
๐กDischarge resistors
๐กMotor run capacitors
๐กUltraviolet effect
๐กProlong LED life
๐กLED fixtures
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 1ฮผF capacitor
11.5W with 2ฮผF motor run capacitor
24W with 4ฮผF 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
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