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 #126 – How fast can you update an e-paper display?

Welcome to a new voltlog, today we are going to answer the question how fast can you update an e-paper display, is it suitable to display live updating values from a sensor for example? Some people asked these questions in the comments of previous videos so I am doing some tests to try and answer these questions.

Now there will be a big difference between trying to update the whole screen and trying to update just a small section. And that delay might also be related to how fast the processor can send the information to the display. So for example measuring the time passed between sending the first byte of data to the display and the last byte going out is not that relevant, it might just be a slow processor, and the display could accept data much faster.

Also in the case of an Arduino the ram size is very limited so a full buffer could not be implemented. This means sending of the data to the display is done inefficiently increasing the time it takes for a full update.

Link e-paper display black/white:

More resources below:

Voltlog #120 – Mini DC Power Supply Review

So I guess a gadget like this is worth 10$ because you could replace that linear breadboard power supply with a more efficient one, which will give you voltage and current display as well as adjustable output.

Here are some images I took during the teardown of the mini power supply:

 

 

 

 

 

 

 

Checkout this power supply from the links below:

60W Electronic Dummy Load Battery Tester:

Voltlog #31 – InTheMail

Usually when I order stuff from China mainland to Romania it takes about 3-4 weeks to arrive while stuff from Hong Kong takes about 5 weeks to arrive. However every year orders placed starting from about 15th of November up to 31st of December take very long to arrive sometimes even arriving after 8-9 weeks. So right now about a third of my orders are late or missing because there is also a good chance they will never arrive once they go past the 8 weeks mark.

A list with links for all the items shown is in the video description so do check them out.