The Joule Thief. Tutorial: How to Make LED Cubes. The warm ambient glow of the LED Cube’s fantastic display of illuminated animation and hours of programming. They’re actually easier to create than you may think. We’ll show you how in plain English using simple designs and multiplexing Let’s start off small: Bigger means Better: 8x8x8 is a bit more complicated, but is definitely worth the effort. Absoulte Insanity! Did I hear someone say 1000 LEDs? Need LEDs? Make a Joule Thief! RGB Computer Controlled LED Bottle Wall. Driving an LED with or without a resistor. In this post I will try to show, why it’s a good idea to use a current limiting resistor for an LED. And when it’s save to drive the LED without any resistor. If you read about LEDs, you will notice that everyone tells you, that you need a current limiting resistor.
But mostly they do not tell you why. LED with current limiting resistor If you look at a datasheet of an LED, you will notice that graphs shown are not linear. If you apply a specific voltage to a resistor, you can compute the resulting current with: I = V / R Example: I = 5 Volt / 100 Ohm = 50 mA Obviously that does not work with LEDs because they don’t behave like a linear resistor. So it’s vital to stay within the limits of the LED.
Assuming, we have a red LED with maximum rating of IF: 25 mA at VF: 2.1 Volt. R = V / I = (5 Volt - 2.1 Volt) / 25 mA = 116 Ohm. To be safe we use a 120, or better, 150 Ohm resistor. R = V / I = (5 Volt - 2 Volt) / 20 mA = 150 Ohm. Ok, 150 Ohm is fine. P = V * I = 3 Volt * 20 mA = 60 mW 4. Links. Greencamplite - Home. Flashlight Without Batteries--from the book, "Haywired". In this project, you will make a flashlight that works without batteries. Even more amazing, you can recharge it in three minutes and it will run for more than 24 hours. Because the ultra capacitors can be recharged thousands of times, you may save the environment from ever receiving an old flashlight in the trash system. This project is from my book Haywired Click here to order a copy from the Chicago Review Press.
Parts List (2) 220 farad capacitors, www.digikey.com, #589-1013-ndInsulated wire, black and redSolderLED, high brightness, www.jameco.com, #21752512" x 12" acrylic plastic sheet, 1/8" thickPermanent marker(2) C clampsEpoxy1/4" jack, Radio Shack, #374-280Metallic tapeSPST rocker switch, Radio Shack, #275-693GlueElectrical Tape Tools List Wire cuttersSoldering IronScoring knife (for plastic)Single-hole paper punch3-volt DC power supply--700 milliampDrill1/4", 1/16", and 3/4" drill bitsMetal straightedge. Programmable LED. An LED is used as output. As input I used an LDR, a light dependent resistor. This LDR changes its resistor as it receives more or less light. The resistor is then used as analog input to the microprocessors ADC (analog digital converter). The controller has two modes of operation, one for recording a sequence, the other for playing back the recorded sequence. Once the controller notices two changes of brightness within half of a second, (dark, bright, dark or the other way round), it switches to recording mode.
In recodring mode the input of the LDR is measured multiple times a second and stored on the chip. If the memory is exhausted, the controller switches back to playback mode and starts to play the recorded sequence. As the memory of this tiny controller is very limited, 64 bytes (yes, bytes!) Mathmos Wind Lights. Make Your Own Custom Glowing Etches - Instructables - DIY, How T. Solar Powered Temperature Sensing LEDs - HacknMod.com - Amazingl. What They Are and How They Work The Glowies use a small microcontroller, but they are really quite simple in both parts and function. The core of the unit is a silicon diode used as a temperature sensor (actually, two of them). These Glowies sense when temperature drops, and it turns blue. If the temperature rises, it turns red. Plus, it’s completely solar powered, so you never have to change the battery. And I used very inexpensive parts, so you can’t get much cheaper!
One of the diodes sticks out a little from the Glowie and serves as the main {*style:<a href=' sensor{*style:</a>*}.