Voltlog #229 – What’s The Smallest Digital RGB LED?

Welcome to a new voltlog, today we’re talking about RGB LEDs. Everyone knows and probably uses digital RGB LEDs these days because they’re convenient, you only need a single pin to control then, they can be chained one after the other creating long addressable RGB strings, you don’t have to worry about driving them with constant current, in fact they even have digitally controlled brightness settings so they’re pretty convenient.

Since these are digital, they have a built-in controller chip, and if we take a closer look at one of these LEDs which comes in a 5050 package, we can see the driver chip and the 3 LEDs red, green blue with their corresponding bonding wires. There are two popular drivers chips the WS2812 and the SK6812 and each of these might have different revisions as well. The WS2812 was the original one on the market and then the SK6812 appeared and is considered a clone of the WS2812 but brings some improvements. The SK6812 has doubled the pwm frequency at which it drives the LEDs which is always welcomed as it helps with reducing flicker and also the timing requirements are a bit tighter but existing WS2812 libraries should work fine with the SK6812.

Voltlog #197 – Wiring LEDs Correctly Series vs Parallel

Welcome to a new Voltlog, today we’re talking about LEDs, light emitting diodes and how we can connect them if we have multiple units. This is one lesson I wish I knew from the start because back when I started tinkering with electronic circuits I built a few projects with LEDs which let’s say could have been made better if I knew the stuff I’m gonna present in this video.

So let’s start by giving you a short story about this project I built back in 2010 so, 10 years ago I saw this project made by Ladyada, I believe back then Adafruit was just starting, they were selling just a few kits. The project was called tv-b-gone and it was a small microcontroller with an IR emitting diode, and it contained power off codes for most available tvs. The purpose was to point it at a TV, upon activation it will cycle all the codes and eventually the TV would turn off. Obviously a fun project that could potentially torment those around us.

So I decided to use a bunch of IR LEDs to increase the power of this circuit. And this is where I made the mistake of having all LEDs in parallel each with its own current limiting resistor. This meant I had to drill and install a bunch of different resistors and due to variations in the resistor value, the leds were running at slightly different currents, outputting slightly different power levels.

If I were to redo the circuit today I would probably connect them in series and use a boost circuit to drive the series string with constant current.