Renewable Energy Questions/Discussion > Renewable Energy Q&A
Using High Power LEDs to Make Lights
WooferHound:
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.
WooferHound:
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.
Wolvenar:
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.
WooferHound:
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.
WooferHound:
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: ---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
--- End code ---
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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