Tag Archives: LEDS

Charlieplexing on the Raspberry Pi

If you suddenly find the need to control many LEDs and do not have the requisite electronics to do so, you can turn to your single board computer, the Raspberry Pi (RBPi) and use it to charlieplex the LEDs. Charlieplexing is named after Charlie Allen, the inventor of the technique. Charlieplexing takes advantage of a feature of the GPIO pins of the RBPi, wherein they can change from outputs to inputs even when the RBPi is running a program. Simply setting a GPIO pin to be low does not allow enough Read more [...]

Dimming LEDs with PWM Generator

nlike incandescent bulbs, dimming Light Emitting Diodes (LEDs) is not an easy task. Incandescent bulbs operate on alternating voltage supply, whereby using Triacs, one can control the effective RMS voltage applied to the bulb. Moreover, since the incandescent bulbs are resistive elements, a simple reduction is voltage is sufficient to reduce the current through it, thereby reducing its light and heat output. LED operation is different, as they work on direct voltage. Each LED requires an optimum Read more [...]

Blinkt! is Compatible with the Raspberry Pi

If you are interested in learning how to control RGB LEDs with the Raspberry Pi (RBPi) single board computer, Blinkt! provides a simple way to interface. Blinkt! is a strip of eight superbright RGB LED lights that you can connect to the RBPi without wires, so it is an easy way to start. Blinkt! Has a female connector that matches the male GPIO connector on the RBPi, and that allows the tiny LED board to sit atop the RBPi. The RBPi can individually control each of the eight APA102 RGB LEDs on the Read more [...]

What is a QLED?

Recently, Samsung has announced their new TV technology using QLEDs to counter the OLED TVs that LG and others have put on the market. QLED stands for Quantum dot LED, and though Samsung has been using the concept of quantum dots in its TVs for quite some years now, they claim they will be bringing out several flavors of the QLED technology. According to Samsung, QLEDs are transmissive, as LCDs are, and light goes through several layers to create an image on the surface of the screen. The company Read more [...]

Multicolored LEDs Create Secondary Colors

Any student of physics knows mixing two primary color light sources produces a secondary color. For instance, mixing the primary colors red and green creates the secondary color yellow. There are three primary colors—Red, Blue, and Green. This process is easily seen in tricolor and RGB LEDs. There is a disadvantage in this method. As two primary colors are necessary for generating a secondary color, two LEDs must remain turned on at the same time. Therefore, generating a secondary color means Read more [...]

Quadriplegics Can Control Exoskeletons with Their Brain

Artificial limbs help people who have lost a part of their arms or legs to regain partial functionality of their extremities. However, for those who have lost control of a major part of their bodies and thus rendered quadriplegic, artificial limbs are not of much use. For addressing such and other whole-body disabilities, exoskeletons are showing great promise. Scientists working at the Technische Universitat Berlin and Korea University are creating such lower-limb exoskeletons. The control system Read more [...]

Pi Lite: Bright White LED Display with the Raspberry Pi

If you did not know, you can run many LEDs with the tiny, credit card sized single board computer popular as the RBPi or Raspberry Pi. Among the many accessories made for the RBPi using LEDs, Ciseco makes one that is very interesting and useful. This is a display panel using bright white LEDs and aptly named the Pi Lite. You can use the series of white LEDs on the Pi Lite as a scrolling marquee for a Twitter feed, for displaying real-time weather information or stock quotes. You can use it to display Read more [...]

Why is Li-Fi better than Wi-Fi?

Imagine wandering through an art gallery with your PDA. As you reach an interesting canvas, your PDA starts downloading information about the painting. When you move to another, your PDA displays content relative to the current piece of art. This is called content fencing – tailoring information to specific locations so that users receive information relevant to their current location. Content fencing is impossible to achieve with Wi-Fi – radio waves have a far greater spreading power. However, Read more [...]

Connecting to the web via LEDs: Li-Fi

Connecting to the Internet is best done through copper wire or high-speed wireless connections. Not many are aware of an additional method – using light beams. This is accomplished not by the usual optical fiber stuff, but by using LEDs. Communication with lights is nothing new - it has been done before. The Scottish scientist, Sir Alexander Graham Bell had invented an arsenal of instruments for communication and these included Photophones. The first instruments to use light for communication Read more [...]

Battle the Sun with a 21W LED and a Raspberry Pi

Lighting up an LED or an array of LEDs and controlling their brightness is a simple affair with the tiny credit card sized single board computer popularly known as the Raspberry Pi or the RBPi. The RBPi runs a full version of Linux and you can use it to drive an array of bright LEDs with it. If you construct it like Jeremy Blum did - he put up the LEDs on his graduation mortar board and wore the RBPi on his wrist on his graduation day - you can be sure of getting a lot of excited remarks from friends Read more [...]