by w2aew @ youtube.com
The Humanalight is a simple single-cell flashlight kit that will produce usable light, even from a “dead” AA battery. Circuits like these are often called a Joule Thief. This term has been applied to just about any circuit that allows you to boost the voltage from nearly depleted batteries for some other low-power application – such as lighting an LED. Strictly speaking, a Joule Thief circuit is an Armstrong style blocking oscillator that uses a bifilar wound transformer and relies on the saturation characteristics of the core to produce oscillation. This flashlight uses a simple two-transistor relation oscillator. A description of the circuit is given, and its operation is examined by viewing the waveforms on an oscilloscope. The proceeds from the sale of this kit benefit the “Ears To Our World” charity which provides self-powered radios and other technology to rural, impoverished and remote regions of the world.
Circuit Walkthrough: A single cell LED light - [Link]
MUNICH — At Electronica last week, the LED manufacturer Everlight introduced what it claims to be the world’s first colour-temperature tunable LEDs in a simple chip on board (COB) package.
After brightness dimming, tunable color temperature is a feature that allows end users to tune the warmth of the light they receive. Typically, this feature is implemented through the use of multiple LEDs binned from cool white to warm white, behind a diffuser.
With its CHI3030 27V/29W series, Everlight claims to have a very compact solution, with LEDs packaged behind concentric layers of phosphors offering different color temperatures of white. Depending on how much warm white or cool white you choose to light up, you can get a precise color-temperature mix.
New LEDs offer tunable color temperature - [Link]
by dany @ elecfreaks.com:
Smart RGB LED Strip is based on the development of our BLEduino, using the Bluetooth 4.0, and the sample code written by EF men, by mobile phone APP, to control the switch of RGB LED strip, and the RGB LED color changing. The main principle is that using BLEduino mega328P chip three PWM pins respectively to control the RGB LED strip of R G B three colors. When the phone APP and BLEduino bluetooth pairing connection succeed, phone APP can control mega328P chip three PWM pins output value, then control the the color of the RGB LED strip
Smart RGB Strip with BLEduino DIY Guide - [Link]
Infineon have announced two shields for the Arduino development environment. The RGB LED Lighting Shield (shown left) provides three independent output channels with a DC/DC LED driver stage to give flicker-free control of multicolor LEDs. It is fitted with an XMC1202 microcontroller using a Brightness Color Control Unit (BCCU) to help off-load time-critical events from the Arduino processor. The Shield can be expanded by adding an optional isolated DMX512 interface for stage lighting control and audio nodes or a 24 GHz radar sensor for motion detection.
Arduino Shields from Infineon - [Link]
by Vladimir Oleynik @ edn.com:
To measure a zener diode’s breakdown voltage, you need a dc voltage source whose voltage exceeds that of the zener voltage. In Figure 1, resistor RSER provides voltage drop between VIN and VZEN. In any case, VIN should exceed VZEN. Resistor RSER must provide current, IZEN, that can keep the zener diode in reverse breakdown. That is, the current must be more than IZEN-IZENMIN and less than IZEN-IZENMAX. You also need to consider the current that flows through the load. Otherwise, VZEN will be unregulated and less than the nominal breakdown voltage. Also, the power that the zener diode dissipates should not exceed the manufacturer’s specifications. Except for the value of IZEN-IZENMIN, all necessary data appears in zener-diode data sheets.
Circuit lets you measure zener voltages and test LEDs - [Link]
Build a cheap and simple full software controlled step-up (boost) converter to drive a LED string of 10 LEDs. LEDs are used as string to light up a acrylic engraved plate placed in a holder (also made out 5 layers of lasered black acrylic glas). Step up is from 5V to about 30V, current regulated to about 20mA.
LED step-up converter with ATtiny85 - [Link]
Francesco Truzzi published a new build, a 3-channel (RGB) LED driver:
I built another board, which is a 3-channel (RGB) LED driver based on an inexpensive chipset called PT4115 (you can find them on eBay or Aliexpress).
The circuit is very simple and looks like Sparkfun’s PicoBuck. However, I used beefier components and a different chip. You may say it’s pretty much the same thing, but I made it to learn some more about PCB design.
Datasheet here. LED current is set through a sense resistor. The output current I is equal to 0.1/Rs. I wanted ~300mA for each channel so I chose a 0.33 ohm resistor. If you want 350mA, choose a 0.27ohm resistor.
Each channel can be controlled via PWM (you can solder male/female headers on the board), for example with an Arduino.
Building a 3-channel, high power RGB LED driver - [Link]
Raj @ embedded-lab.com shared his recent project. It’s a mcu controlled dice based on PIC mcu:
Tons of LED dice projects with different output forms have been published online. The most common output configuration in those projects is a 3-1-3 setup (two rows of three LEDs and one LED at in the middle) of seven LEDs, which simulates the actual patterns of dots found on the six faces of a traditional dice. When it is rolled, one or more LEDs are selectively turned on to display a random number between 1 to 6. This project is about a similar LED dice but with a slightly different output form. It uses 6 LEDs which are arranged in a circular pattern and are labeled 1 through 6. They create a chasing effect when the dice is rolled. The chasing effect slows down gradually, and eventually stops at one of the six LEDs. The rolling is done by a gentle shaking of the dice horizontally. The LED dice is powered with a 3V coin cell battery and uses PIC12LF1822 microcontroller to generate a random number and drive the output LEDs.
MCU running LED dice - [Link]
by Digi-Key Corporation:
The Cree LMH2 LED Module provides unparalleled efficacy and light quality in a fully integrated module. Utilizing Cree’s True White Technology, the LMH2 provides beautiful 90 plus CRI lights in 4000 Kelvin, 3500 Kelvin, 3000 Kelvin, and 2700 Kelvin color temperatures. In addition, the LMH2 delivers 97 LPW efficacy across all CCT and lumen options. There are two lens options. The flat lens provides an 82 Degree Beam Angle while the Dome lens provides a 100 Degree Beam Angle. In addition, there is a Unique Driver Compatibility Program that provides a list of tested and recommended drivers for the LMH2. There is also a 5-year warranty on the module, even for those utilizing a third party driver. Finally, the aluminum housing provides tremendous thermal design flexibility.
Cree LMH2 LED Module Versus Traditional CFL Options - [Link]