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LED Light String Types - Part 1

Updated: Oct 23, 2022

On the Internet, if you type "Fairy Lights" you will get millions of hits (86.8 Million in .83 seconds on Google!)

Most of these string-type LED sets are single-color with either no control beyond On and Off, or they have a controller that can do some fading and blinking, but the entire string does the same exact thing, whatever that is.

The next step up is RGB LEDs. These can display more than one color and most can do over 16 million different colors, more than the average human eye can even detect!

LEDS like this one from Digi-Key and sold as a New Tone Electronics part are "dumb", meaning they do not manage the color themselves. There are leads for Common, Red, Green and Blue and the user has direct access to the Light Emitting Diodes inside.

That means external circuitry must limit the current that flows through each diode, to set overall color and prevent the LED from being damaged.

When we put LEDs like this together in a string arrangement, it becomes VERY complicated to manage the current flowing through each LED Diode. Since the diodes have slight "imperfections" in them that change the efficacy (the efficiency of converting electrical current to light) it becomes very obvious to the eye, when we see bright spots or dim spots in the string. So, what to do? Delegate Control!!

This is a nice little 50 millimeter by 50 millimeter (hence the "5050" package) Smart LED. The LED Controller IC built-in does a few different functions. First and foremost, it drives the R,G and B Diodes using a constant current driver circuit that eliminates most of the need to bin (sort for brightness). Then it pulse-width-modulates the signal driving the diodes to make them dim from 0% to 100% brightness. It can do this over and over with no external data input.

Now, since the controller does all that work, and does it usually at a pretty fast clip, it needs to know what R, G and B brightnesses to set. It gets that information from a String or Channel Controller. There is a defined set of protocols, both physical (electrical) and data-centric (the meaning of data that is sent and the order of it all). There are a few different protocol versions designed by different LED manufacturers, but the WS2811 data standard is probably the most popular.

Please join me in Part 2 of this series!

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