Tag Archives: Led(s)

App note: 12Vac LED Driving without smoothing capacitors

via Dangerous Prototypes

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Application note from Diodes Incorporated on driving 12Vac LED without smoothing capacitors with their Zetex ZXLD1360 LED driver IC and SBR2A40P1 super barrier rectifier. Link here (PDF)

LED based architectural lighting is now coming of age, but there are still some problems to be considered when designing luminaires to be fitted into existing installations.

This Application Note discusses some of the challenges and shows that the omission of the traditional smoothing capacitors has advantages in saving cost, space and PFC problems.

An Arduino-powered backlit Clemson Tiger Paw

via Arduino Blog

Most people support their school or favorite sports team by buying a shirt or tuning into games. Jacob Thompson, however, took things one step further and created his own Arduino-powered, backlit Clemson Tiger Paw.

Thompson’s “WallPaw,” as he calls it, uses an Arduino Uno to receive signals from an infrared remote and to pick up sounds with a small microphone. This information is passed on to an Arduino Mega, which controls a five-meter-long strip of WS2812 LEDs to provide lighting effects.

He notes that it would be possible to use only one Arduino board for everything, but patterned his code after this tutorial that included two. The paw itself is cut out of wood and clear acrylic, allowing the lights underneath to shine through nicely.

You can see the build in action below and find more details on Thompson’s website here.

Driving a 48-segment RGB LED bar graph with a Teensy 3.2

via Dangerous Prototypes

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Glen Akins writes:

In my post Driving a SparkFun 48-Segment RGB LED Bar Graph, I stated that the hardware built there could be used to drive the LED bar graph with any combination of hardware and software that could drive one of the common 32×32 or 32×16 RGB LED matrices. Today I’m back to prove that point. In this post, I ditch the FPGA and drive the 48-segment RGB LED bar graph using a Teensy 3.2 board and the Pixelmatix SmartMatrix 3 library.

More details at Glen Akins’ blog.

Using a Decade Counter to Make LEDs Flash

via hardware – Hackaday

[Andrea De Napoli] created a LED display consisting of a half-dozen LEDs connected to the inverted signals of a CD4017 decade counter, giving the effect that a dark LED is running back and forth. The CD4017 works by activating 10 outputs, one at a time, as controlled by a clock signal sent to pin 14.

The first and last LEDs are lit by outputs 0 and 5 with the help of a PNP transistor and a 12K resistor. The middle four LEDs are switched by two outputs each and go dark when one of them goes high. [Andrea] really delves into the CD4017 and he shares a lot of detail in the project page.

Hackaday publishes a lot of posts about obscure ICs: Project 54/74 aims to create a database of die images of 5400 and 7400 series ICs. In a remix of a classic, the Baby 10 uses a 4017 to make a music sequencer.


Filed under: hardware

App note: How to measure thermal resistance of LED emitters and LED arrays

via Dangerous Prototypes

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Another white paper from Lumileds about LED thermal resistance. Link here (PDF)

Thermal performance is the most critical factor of a well-designed LED lighting system. A lighting system with proper thermal design has higher efficacy, meaning more light can be extracted using less energy, and better long term reliability.

App note: Flash for “Selfies”

via Dangerous Prototypes

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Effective front facing camera flash discussed in this white paper from Lumileds. Link here (PDF)

Smartphones are ubiquitous in everybody’s daily lives, a trend that shows no sign of slowing. A key component of the smartphone is the camera, which has gained market share over Digital Still Cameras due to its convenience.

As the demand for smartphone cameras increases, sensor makers are continuously working to improve the resolution and while 20MPix capability gained in importance for the main camera of the smartphone, the resolution race has begun for the front camera. With the rise in popularity of “selfies” and the 5 to 8 Mpix resolution for the front camera, it is not surprising that camera flash is starting to be more readily implemented for front cameras also. However, to make a successful front flash that captures an ideal “selfie,” there are certain illuminance requirements and shorter flash pulses that are recommended.