background preloader

LED Flashlights

Facebook Twitter

LED's efficiency exceeds 100% ( -- For the first time, researchers have demonstrated that an LED can emit more optical power than the electrical power it consumes.

LED's efficiency exceeds 100%

Although scientifically intriguing, the results won’t immediately result in ultra-efficient commercial LEDs since the demonstration works only for LEDs with very low input power that produce very small amounts of light. The researchers, Parthiban Santhanam and coauthors from MIT, have published their study in a recent issue of Physical Review Letters. As the researchers explain in their study, the key to achieving a power conversion efficiency above 100%, i.e., “unity efficiency,” is to greatly decrease the applied voltage. According to their calculations, as the voltage is halved, the input power is decreased by a factor of 4, while the emitted light power scales linearly with voltage so that it’s also only halved.

Light emitting diodes bring relief to young cancer patients; NASA technology used for plant growth now in clinical trials - Marshall Center Space News Release 03-199 (11-13-03) For release: 11-05-03 Release: 03-199 Light emitting diodes bring relief to young cancer patients; NASA technology used for plant growth now in clinical trials A device using specialized light emitting diodes, based on NASA technology for plant growth in space, is continuing to show promise as a treatment to aid healing of bone marrow transplant patients.

Light emitting diodes bring relief to young cancer patients; NASA technology used for plant growth now in clinical trials - Marshall Center Space News Release 03-199 (11-13-03)

Use of the LED apparatus has advanced to the second phase of clinical trials in U.S. and foreign hospitals. Results from the first round of tests were highly encouraging, prompting researchers to expand the trials as they seek approval for the treatment as a standard of care for oral mucositis. Photo: Light emitting diodes can ease pain and promote wound healing in bone marrow transplant patients. Light Technology Successfully Reduces Cancer Patients Painful Side Effects from Radiation and Chemotherapy. LED driving and controlling methods. PAGE 1 of 6 - LED voltage control with limiting resistor Quick info about LEDs This is not an LED theory page, therefore i will not go into details about the LEDs.

LED driving and controlling methods

You can read the LED Theory for more extensive info. There are some things though that you need to have in mind: LEDs are current-depended components. LEDs have different forward voltage. LEDs have polarity. The maximum forward voltage is critical. How to Build Your Own Ultraviolet UV LED (Black Light) Flashlight. I find it easiest to do everything assembly-line fashion.

How to Build Your Own Ultraviolet UV LED (Black Light) Flashlight

Lay out your LEDs, push button, resistors, and wiring harness for the battery. Tin all legs of the components and the ends of the harness as well as the legs of the button. The wires on the harness are pre-tinned, but you want to be sure that the solder you're using sticks well to the components, so I always resolder them. Clip the leads on the resistors so they have one long lead and one lead about 1/4" long. Take three of the LEDs and clip the longer lead so that they're about 1/4" long. Now take the other three LEDs and clip the long leads so that they're about 1/4" long. You'll want to figure out how you want to mount the LEDs. I used either a roll of tape or the solder roll as a work stand at this stage. Lighting Circuits-Diagram and LED Light Circuits Schematics. LED Projects. Nice Light Emitting Diode Projects This CircuitBook section is no longer updated, but still holds the maximum resources.For more and better listing, visit our new Electronics Projects Page CircuitBook >> Opto Electronics >> LED Projects Switched flashing LED The idea was to have two LEDs, one is flashing all the time and the other one joins in as long as a switch is pressed.

LED Projects

The LEDs then flash alternating. Deep darc » Hacking Christmas Lights. I went to Costco the other day with my wife to pick up some Christmas lights.

deep darc » Hacking Christmas Lights

While there, I found the most awesome christmas lights ever: the GE Color Effects G-35. This string contains fifty "bulbs". Each bulb contains a red, green, and blue LED—allowing for any color to be produced. The biggest drawback is how you control them: there are 14 pre-set "programs" that you can select, and they are all pretty lame. However, with a little reverse engineering and an Arduino (or any other microcontroller) they can be made into the coolest Christmas lights on the block. My christmas lights, hacked to display a rainbow. I wanted to share my efforts so that other people can give this a try. Arduino LED Exploration. Arduino LED Exploration My program shows you all of the data on your Led from the first light to the normal operation light.

Arduino LED Exploration

From that data you can pick an RS that is good light, but lower in current. You must build the circuit to run my program. You must open a terminal window when you run my program. High Power LED Driver Circuits. Super easy LED flashlight. Current limiting Resistor calculator for leds. Push button normally closed. Simple Current Limiter for LED Flashlights. Undefined SIMPLE CURRENT LIMITING FOR LED FLASHLIGHTSFor Longer Battery and LED Life I have modified my 3-White LED 3-AA cell flashlight by adding filament bulbs in series with the LED's to form a "ballast" utilizing the positive resistance-vs-temp characteristic of tungsten as a simple current source.

Simple Current Limiter for LED Flashlights

I did this to increase the battery life (at the expense of initial brightness), and to increase the lifetime of the LED's. The flashlight, which was given to me, appears to be an early C. Crane unit. Experiments with Bright LEDs : Constant current supply. While preparing for the Year 2000 power grid collapse, which somehow never materialized, I began experimenting with battery-powered room illuminators using super-bright LEDs.

Experiments with Bright LEDs : Constant current supply

I learned a couple of interesting lessons the hard way. First, I found that LEDs tend to draw more current when they warm up. When a bunch of them are connected in series, the effect is amplified. The next thing I found is that LEDs tend to fail shorted, not open. If you have a long string of them in series and one of them shorts, the current goes way up in the rest of the string, and within a few milliseconds, you have a whole string of dead LEDs. Easy LED Flashlight. Power LED's - simplest light with constant-current circuit. Circuit parts (refer to the schematic diagram) R1: approximately 100k-ohm resistor (such as: Yageo CFR-25JB series)R3: current set resistor - see belowQ1: small NPN transistor (such as: Fairchild 2N5088BU)Q2: large N-channel FET (such as: Fairchild FQP50N06L)LED: power LED (such as: Luxeon 1-watt white star LXHL-MWEC) Other parts: power source: I used an old "wall wart" transformer, or you could use batteries. to power a single LED anything between 4 and 6 volts with enough current will be fine. that's why this circuit is convenient!

Power LED's - simplest light with constant-current circuit

You can use a wide variety of power sources and it will always light up exactly the same. LED Zippo Flashlight. Single cell LED flashlight. High efficiency white LEDs have advanced to the point where they can replace glow bulbs and other light sources not only as indicators, but also for illumination. While many of the claims made about the LEDs' efficiency, light quality, lifetime and economy are mostly exaggeration, the truth is that for very low light levels they are now competitive. They have equal or slightly higher efficiency than a flashlight bulb, a longer lifetime, and are very much tougher.

On the other hand, they are still far more expensive than a bulb, for a given light output. Building a LED Flashlight. Building a LED Flashlight by Jeff Polston (October 13, 1997, updated: February 5, 2004) Astronomers crave those pitch black skies. They'll even drive, hike, or climb the tallest mountain to obtain them. They rave about that super dark rural site, where you can't even see your hand in front of your face. Easy to make LED flashlight circuit - Free Electronic projects & 8085 projects. LED flashlight with a power-saving, durable, brightness, and other advantages. Very popular, and here the production of a classic LED flashlight circuit, for your reference. 1,1.5 V low-cost LED driver circuit Ring use T9 * 5 * 3/2K, can also be used T10 * 6 * 5 and so on, with 0.3mm enameled wire and around 20T, terminal connection according to the figure with the same name.

TR1 election 8050 or 9014, D1 4937 election, or 107, PCB made with a piece of scrap board. 2,1.2 v l 3.4v power supply circuit. Simple LED Circuit. Making a simple LED flashlight - Electronics. A Simple and Cheap Dark-Detecting LED Circuit. Here’s a simple problem: “How do you make an LED turn on when it gets dark?” You might call it the “nightlight problem,” but the same sort of question comes up in a lot of familiar situations– emergency lights, street lights, silly computer keyboard backlights, and the list goes on. Solutions? Lots. How to Make a Simple Mini LED Flashlight.