Greeeg at the 430h forum has been working on a RGB LED ring clock:
The clock is comprised of 2 rings of 60 LEDs each. the LEDs are WS2812 parts, which include a built-in driver. The PCB is one of the interesting parts of this clock. I designed the board in altium as a single 6 LED segment. and then left pads at each end to allow them to be soldered onto another segment. Currently I am using a MSP-EXP430FR5739 board to drive it, using some very in-efficient assembly code that requires a 20MHz clock.
RGB LED ring clock - [Link]
Nick Leijenhorst build a 555 PWM circuit to dim his room LED lighting. He writes:
I wanted to dim my room LED lighting with a potentiometer, and decided on creating a solution from scratch to make it more fun and educative. I decided to go with the fairly well-known 555 PWM circuit. To decrease size and for learning purposes I decided on using surface-mount components for the first time. The reason I wanted to make this 555 PWM circuit is actually just to see if I could solder SMD components on home-etched PCB’s, and to see how hard it actually is.
Surface-mount 555 PWM circuit - [Link]
The PicoBuck is a small and inexpensive 3-channel LED driver. It employs constant-current buck driving which approaches an efficiency of 95% (theoretical). It’s based on AL8805 LED Lighting Buck Driver from Diodes Inc.
PicoBuck – RGB LED Driver - [Link]
Dilshan Jayakody wrote a post on his blog about his 3W constant current LED driver:
This is quick post about 3W constant current LED driver which I was design to combine with some homemade furniture piece. The main components of this system is LM311 voltage comparator and IRF9640 P-Channel MOSFET. This module is design to drive maximum of two 3W high power LEDs and it requires 8V – 10V DC (500mA) power source. In this given configuration this module may not need any heat-sink (for IRF9640) and consume maximum of 500mA of power.
DIY 3W constant current LED driver - [Link]
Dave Kruschke writes:
Yep, no transformer and no hard to get IC. But, … two transistors and other parts are required. I actually found this circuit by accident while roaming Colin Mitchell’s Talking Electronics website (talkingelectronics.com). This website is very rich with examples and explanations of a huge variety of circuits. In fact, this website is so abundant in circuits that later on, I couldn’t find the circuit revealed here. Anyhow, I believe that the TE circuit can be considered “robust” as it works even if different parts are used.
“Joule Thief” – no IC and no Transformer - [Link]
Raj @ embedded-lab.com build a mini LED Christmas tree for his son. He writes:
My two and a half year old son loves toys with flashing lights. For this Christmas I thought of making a mini LED Christmas tree for him. This project uses 22 multi-color LEDs which are driven by a PIC12F683 microcontroller using the Charlieplexing technique. The details of the build procedure is described in the following sections.
Making a mini LED Christmas tree - [Link]
By Gina Roos,
Widespread adoption of cameras in smartphones and other mobile devices, together with consumer expectations for higher quality, sharper images are driving the need for simpler designs, smaller sizes, and lower component counts, particularly as many smartphones move to integrate front- and back-facing cameras.
Mobile phone cameras will increase from approximately 1.6 billion units in 2011 to more than 2.2 billion units in 2015, representing 92 percent of mobile phones worldwide, according to Gartner Inc. The market research firm also found that an additional 15 percent of phones would have two cameras to take portrait photos or to enable video chat.
New LED Photo Flash Drivers for Smartphone Cameras Improve Image Quality - [Link]
Zak Kemble writes:
While working on an update for my CPU Usage LEDs project, I thought why not just make it into a universal RGB LED controller? The CPU Usage LEDs controller took a value between 0 and 255, worked out what colour it should be and then fade to that colour. This was very limiting; changing what colours it used and how it fades required a firmware update. With this universal RGB LED controller the host software does all the work and the controller is simply told what brightness the red, green and blue LEDs should be. To make it as easy as possible to interface with the controller I created a library which deals with all the LibUSB stuff.
AVR USB RGB LED controller - [Link]
Kevin Rye designed a simple LED tester:
I decide to put together a small LED Tester board. It’ll be powered by a small coin cell battery. I can pick up an LED with a pair of tweezers and just simply tap it to the solder pads. If it lights up, I know I’m holding it the right way, or not. As far as a PCB, I want it to be super simple and super cheap. I really don’t want to spend $10 bucks on something so simple. However, I don’t want it to be a one-trick pony either. Ideally, it should work for through-hole LEDs as well, as 1206s and whatever other sizes I can’t think of right now. Do SMD LEDs come in an 0805 package? I’ve never seen one, but it’s probably a good idea to place some large pads on it so that it’ll work for anything.
Kevin’s LED tester - [Link]
Andrew Rossignol has written an article detailing his YALEDD – 16×16 LED display project:
The class was instructed to choose a simple circuit such as an LED flasher or a simple sequential state machine composed of discrete logic, capture the schematic, layout the PCB and have it made by the end of the term. I decided that it would be boring to design a simple state machine. I also thought it might be pretty cool to have an electronic gizmo of my own design to show off on my desk at work.
YALEDD! 16×16 LED display - [Link]