Author Topic: Using High Power LEDs to Make Lights  (Read 5506 times)

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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #15 on: November 26, 2018, 09:38:21 am »
I finished the last project that is pictured a few posts up. Bent up a 14ga thick strip of sheet metal to make a Yoke to mount the 10w LED light onto allowing it to be aimed with both Pan & Tilt.

These 10w LEDs are about a 75w incandescent-equivalent providing wonderfully usable light over a large area. This will get placed on top of my computer desk about 6 feet over the floor where it can be swiveled to where the light is needed.

Works great aimed up at the ceiling for indirect lighting. Measured at .8 amp from the 12 volt solar power.

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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #16 on: November 26, 2018, 10:52:29 am »
Finished another project this morning that was posted above as a three level brightness test of a light having capability of 5/10/15 watt settings.

The bell housing is from an old incandescent fixture that has been gutted. The U shaped yoke was bent from a small piece of sheet metal. The top housing is from another old incandescent light. Everything is wired with Ethernet cable because it has 4 pairs of wires in it. Three pairs used coming up from the switches, all four pairs used between the Buck Converters and the main Housing.



Three buck converters are mounted in the Top Housing. Two for the Low (700ma) & High (1400ma) settings and a third for some colored Mood lights (350ma) on the side of the fixture.



The center LED is a 5w for the Low level, the 4 LEDs on the outside are 2.5w times 4 totaling 10w for the High level. The fan on the back of the CPU Cooler runs through an 82ohm resister for quietness on the low 5w setting but runs at full speed on the high 10 & 15 watt settings.



When I was designing this I knew that there would be extra wires in the Ethernet cable that is being used. So Red & Blue LEDs were added to the side to point up at the ceiling and to the side for the wall, to be used as Mood or Party lighting.



At the risk of showing you how messy my computer desk/workbench is, here is the fixture mounted to the ceiling on the high 15w level. Gosh this is hugely bright for 15 watt light. The buck converters have red indicator lights on their PCBoards and they show up through the ventilation holes in the top housing. You can see the 10w light from the previous post, on the very top of the desk on the left under the lamp shade.
Tonight I'll get a picture of the colored lights operating. I will be drinking some local Craft Beer so I will be in the mood for sure.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #17 on: November 26, 2018, 05:41:23 pm »
Now I have Plenty of lights for the area that has 12v Solar Power, so I'll be focusing more on 120vac fixtures for other areas around the house.

The mail today came with 10 more Buck Converters
and an interesting selection of LEDs including . . .
10x 3w Ultraviolet
and an assortment that has 20x 5mm LEDs in ten colors, 200 in all
plus a couple of sets of 1w high Color Temperature white LEDs in the 6k and 10k range

I should point out that these White LEDs are rated to 80 CRI (Color Rendering Index) relating to the quality of light. If Sunlight is coming through the window to compare to, the Sunlight kicks the LEDs ass about light quality. The LEDs seem a bit green and lacking in red. Food looks OK under it, but not great like an incandescent or Sunlight.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #18 on: November 27, 2018, 09:12:13 am »
Here is a pic of the Red/Blue Mood Light working
Nice interesting shades of Lavender

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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #19 on: December 01, 2018, 05:06:32 pm »
Got another coupla projects finished . . .


The first is an Ultraviolet Flashlight (black light). It's a 3.5v 700ma UV LED running on a 4 volt battery with a 1 ohm dropping resister and a switch. This UV LED is 3 watts and is very effective at making fluorescent materials light up without throwing too much visible purple light out. Should run about 3 hours with the 2200mah Lithium 18650 battery.


The next project is for lighting up my computer keyboard. I used some small LED flashlights, replaced the original LEDs with some extra bright 5mm LEDs, and Folded some metal parts to make a small light that is easy to aim where it's needed. Removed the batteries and wired the 2 small fixtures in series for a small 6v 20ma load. Powering these from a buck converter that is barely able to control a little 20ma load. These are mounted over both sides of the monitor lighting the keyboard from above.


Last is a project for running a spotlight for my job in a theater. We use Spot Sights to line up on the target before fading the intensity up. Here is what it looks like to look through the small Heads Up display on the Unit.


These Telrads use two AA batteries. I cut out the batteries and powered it with a 5v phone charger. It has a 2v red LED for the target sight, but I added more LEDs to light up the area where I sit to run the spotlight. Now on the side facing down at my lap, I have 2 pairs of 5mm LEDs, individually switched for White or Blue.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #20 on: December 12, 2018, 07:35:26 am »
Been playing with LEDs some more and made a coupla more small projects. They use only colored LEDs and are intended to be more like Art than useful lighting. These are running on wall-wart transformers

One of the devices was going to use 5 different colors in Series. It was assembled, but the Red LED wasn't working. Replaced that LED twice and discovered later, both LEDs tested good. The Bottom Plate on these LEDs are designed to dissipate excess heat onto the surface they are mounted on. After some testing I found that all my LEDs are electrically isolated except the Red & Deep Red ones. So the surface was cleaned and I applied a thin piece of Cellophane tape, then glued the LED down and all was fine.



Here are the 2 new Projects.
On the left is the 6 color Rainbow effect that was causing the problems mentioned above. The 5 colors are: Deep Blue, Blue, Green, Red and Deep Red. They are all 1w LEDs wired in series and add up to about 14.5 volts with current set to 350ma, powered Using a 19vdc wall-wart power supply.
On the right is a simple 2 color effect that uses 1w Deep Blue and Deep Red LEDS. These LEDs total 7 volts in series and are set to a current of 350ma using a 9vdc wall-wort power supply.



The Rainbow Effect about 5 inches from the wall. This reveals that the intensity of light isn't very evenly distributed from the individual LEDs, but it still looks great in person. The deep colors aren't presented well by a camera or computer monitor. It gets fairly warm to the touch, but not hot. I had added some small heatsinks to the inside of it to help out some.



This is the Deep Blue and Red effect at 5 inches from the wall. Once again you can see the rough light distribution but still looks super cool. Gets warm but not hot.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #21 on: December 18, 2018, 12:46:41 pm »
Today I woke up with a hangover and decided to do something Easy. So I ended up making 5 Nightlights. Two have Natural 4500k White, then 2 more white ones that are Warm 3000k and Blueish 10000k. The fifth one is Colored Blue. I found some old incandescent nightlights and Used the Clear lens covers on these LED remakes. They are all powered with a 5v wall-wart charger, Glued together using 5-minute Epoxy. The heatsinks are 1x3 inch sheetmetal strips bent to fit the wall-warts.



They all use a 1w LED glued to the sheetmetal with a 4.7 ohm 1w limiting resister. These lights use almost 2 watts and get warm to the touch when running. The resister gets rather warm too dropping 5v to 3.5v at 350ma. In fact, the short thick resister lead transfers a lot of heat and it is heating up the LED too much. If I make anymore nightlights I'll make the lead much longer to keep the heat farther away from the LED.



I bought a pound of solder at a Hamfest and it's not very good. I is a rosin core solder but it takes a high heat to make it work right and makes a crust on the soldering tip that is hard to remove even with a wet sponge. Got some new solder on order.
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Offline Wolvenar

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Re: Using High Power LEDs to Make Lights
« Reply #22 on: December 19, 2018, 08:41:14 am »
Sounds like you bought the newer no, or low lead solder. In my opinion the stuff sucks for general hobbyist use.
MG Chemicals 60/40 is my go to I guess. It might be a bit more $ compared to some you can get, but it is worth it to me to have consistency.
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #23 on: December 29, 2018, 02:22:14 pm »
I am about halfway finished with another Art project which will project 120 Fast Color Changing RGB LEDs onto the wall or Christmas tree or anything else.


There is a 12 x 11 grid of LEDs, minus 3 from each corner so the image will have some roundness.



Color Changing LEDs are dependent on a certain Voltage on the input and the current limiting is done by the microcontroller onboard each RGB LED. These LEDs are rated 3.0-3.4 volts and I'm giving them the full 3.4 volts to insure best brightness. All 120 LEDs are wired in Parallel. It took over 2 hours to get the PC board made.



These LEDs Flash 2 to 5 times a second and do fast color fades too. I took some pictures but since the LEDs are flashing, about a third of them will be off at any instant. This ends up being a very Busy and Exciting display that can't be captured in a photograph.



This is being powered from my 12v solar power right now, but I will be using a 120vac powering a 6vac transformer to make an 8.5vdc power supply feeding a Buck converter to get the needed 3.4v to feed the panel. Measured the Current draw from the buck converter to the panel and it averaged about .9 amp at the 3.4 volts, so it's a little more than 3 watts to the LEDs.



It works really good and is really bright, showing up real good in bright light. Unbelievably busy Dancing Patterns. Changing the Focus makes some great effects and it will be built to make the focus easy to adjust. I've gutted an old Meteor Liteflower disco light and will be placing everything inside of that.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #24 on: January 22, 2019, 09:09:50 am »
The Buck Converters that I'm using to control Current to my LED projects don't work very well below 100ma. It drives the converters PWM frequency too low and will flash the LED if there are no capacitors on the output. I'm working with all kinds of LEDS right now and need low currents a lot so I've started to use the LM317 variable voltage regulators wired into Current Limiting mode.



This requires a resister to set the output current and here are the values needed to set the current on the LM317

Code: [Select]
Ma -- Ohms
 20 - 62.5
 40 - 33.3
 60 - 20.8
 80 - 15.6
100 - 12.5
120 - 10.4
140 -  8.9
160 -  7.8   1/4w
180 -  6.9  ^^^^^^
200 -  6.3  vvvvvv
220 -  5.7   1/2w
240 -  5.2
260 -  4.8
280 -  4.5
300 -  4.2
320 -  3.9
340 -  3.7

So this works OK up to about 160ma, then the resister values need to be too precise and it starts generating heat. My buck converters work great above 120ma and these LM317 regulators work great below 120ma. I also discovered the CL2N3-G regulators. They are hardwired to 20ma and work up to 90 volts which can be very useful.
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Offline rossw

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Re: Using High Power LEDs to Make Lights
« Reply #25 on: January 22, 2019, 06:29:13 pm »
I've been doing a fair bit of late with some battery-powered LED applications, a bit like you Woof.
I've come to the conclusion that series linear regulation is a dead-end.
It does have the benefit of simplicity, I'll grant it that. But that's about its only benefit.
The wasted heat is power your battery is giving up that SHOULD have been used in making light.
So either you get less light output for you battery, or less run-time.

I've been making some indicators. These are 4 x 1W LEDs, I believe very similar to the ones you are using.
The PCB acts as a bit of a heatsink, but I'm also not driving them to their full power, to reduce heat and extend life.



The HUGE difference here is that with this circuit, I can run 4 or more white LEDs (or any other colour!) at high brightness, off a SINGLE 18650 CELL. (It'll work from about 1.8V to 5.5V). The boost converter uses a very small value resistor (I'm using 2.2 ohms) to set the current, so there is almost no heat or waste power in the resistor. Under a thermal camera, the only part of this board that gets detectably warm is the inductor, and even that is only about 4 degrees above ambient.

In the interests of power conservation, I would urge you (and anyone else dabbling with power LEDs) to skip the series resistor, and/or linear regulator solutions, and go straight to a switch-mode converter using a very low voltage sense (feedback) control. The one I'm using tries to maintain 0.25V across the feedback resistor.

Additional benefits they bring to the table is a "brightness" input pin that can be driven by PWM, or by an analog input, to dim the LED from basically nothing to 100%, with virtually NO LOST POWER. Nothing gets warm. 92% or 96% or something of your battery power gets to the LED, none of this "dropping lots of volts (at full LED current)" nonsense.

Just to demonstrate the point - in your above linear option, you're going to drop 1.25V across your resistor 100% of the time. So lets work at 100mA (where I have mine set). If you have 4 LEDs at 2.3Vf that's 9.2V across the LEDs. With your battery full and sitting at say, 12.8V, that's 3.6V you have to drop across the regulator. 1.25V across the resistor (125mW) and 235mW across the LM317, for a total of 0.36W wasted as heat from your total of 1.28W drawn from the battery.
As the voltage goes up, the worse this gets. At 13.8V, it's 4.6V to drop, 460mW wasted from 1.38W drawn from the battery.

The converter option with 0.25V sense would be about 0.99W drawn from the battery with 0.07W wasted as heat for exactly the same LED output!

Offline MadScientist267

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Re: Using High Power LEDs to Make Lights
« Reply #26 on: January 22, 2019, 08:35:29 pm »
I'm in full agreement. Buck converter is THE way to go for driving LEDs.

Linear (and by "extension", simple resistor), as Ross pointed out, is very wasteful at anything above trivial power levels.

"Plain" PWM is riddled with problems as well, and typically still requires the use of some sort of "absolute ballast" to limit current, so while it provides a means to control brightness, it doesn't do it very well (as mentioned, flicker can get really obnoxious) and I'm a firm believer that it's also harder on the LED dies because of the rapid thermal cycling... Even at higher frequencies (yes, law of averages helps there but it's still repetitive "heat and not heat").

Buck conversion (or boost as well, just not quite as common because of the voltages involved) gets around many of the problems associated with either and/or both.

Flicker and thermal cycling are reduced because conversion inherently requires the use of a cap at the output to catch the pulses, and converting rather than dissipating takes a lot of the losses out of the mix, yielding more efficiency. Current limiting is trivial to implement in most chips designed for SMPS (eg buck conversion) and what results is a stable consistent drive for a wide range of input with minimal waste.

For anything more than pretty much indicator LEDs, I personally will never use any other method ever again having seen the benefits of conversion up close for myself.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #27 on: January 23, 2019, 08:14:33 am »
I was trying to point out that the Buck Converters that I'm using don't work very well when set to currents less than 100ma and I'm using the LM317 regulator mainly to power ordinary 20ma LEDs. I'm about to build a small light for my computer keyboard that will require 60ma and I'll use an LM317 for that. There are two 20ma LEDs in series that light up my computer desk that need a LM317 to control them. Earlier I posted about making nightlights with 5v wallwarts and a 5 ohm resister. sure it's wasteful but it was still bright and only used 2 watts which is half the power used by the usual 4w incandescent bulb normally in a nightlight. I plan to get a large number of those 20ma CL2N3-G regulators for many future small projects.
For anything over 100ma the buck converter is the only way to go.

So after all that, I am making a Test Box using four LM317 regulators to give me 4 different current levels for testing LEDs and powering Prototype projects. There will be a terminal strip on top that will provide 4 individual outputs at the following current Levels
20 ma - regular LEDs
25 ma - laser diodes
310 ma - 1w LEDs
640 ma - 3w, 5w and 10w LEDs
When finished this will greatly speed up my project builds and testing new LED orders that I receive. It will be powerd from a Cigarette Lighter plug from my 12v solar power

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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #28 on: February 07, 2019, 05:05:17 am »
I finished my Test Box for experimenting and making LED lights. Has a Cigarette Lighter plug for the input, then then 4 handy Current Limited outputs for testing and prototyping new projects. I've already used it to sort out the color of some LEDs that got mixed together while working on my solar bicycle light project.



Got a buncha new stuff in the mail and testing 4 items out in the center of the picture. . .
-- 5 CPU cooler heatsink fans, $2 each. Got these specifically for using 10w LEDs and they do a great job keeping everything at almost room-temperature while staying quiet running full speed.
-- 3 Blue LEDs 10 watt $2.50 each. One of them is glued to the heatsink in the center. The colored 10w LEDs are brilliant as all the energy is directed into the one color.
-- 3 PWM motor speed controllers, $2 each. Being used as an LED Dimmer these work wonderfully down to about 5% brightness then off. The PWM frequency is 10k.
-- Got a lot of Reflector units in various sizes, some with a lens. These seem to double the brightness of the LEDs while directing the light.
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Offline WooferHound

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Re: Using High Power LEDs to Make Lights
« Reply #29 on: June 14, 2019, 10:22:00 pm »

Building a 20 watt LED Lighting Fixture From Scratch

I've been building small lighting using LEDs and decided to make something that was more powerful and could be considered bright enough to work under.

It uses four 5 watt LEDs with two Buck Converters. A fan was added later because there was too much heat being produced. Not as bright as four florescent tubes 4 feet long, but plenty of light to work under. gets fairly warm but still cool enough for long life.

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