Hand Wiring 2mm Neopixel LED Strips

 While I have occasional tested or prototypes with 2mm using modified surface mount adapter boards, it's always been a real pain. There is a way to point to point solder together the simpler 4 pin Neopixel LEDs.

 I ran across a variation of 2020 size LED with Castelian style tabs that make point to point wiring more practical than typical surface mount components, those with miniature modeling or SMD circuit repair equipmment and experience should be able to handle it.  

Their WorldWideSemi brand numbers are WS2812C-2020 for 5ma and  WS2812B-2020 with 12ma per LED .  

 

Here's an example of the first 5 LED string I tried, the string is 1.2mm long (Using an international standard micro SD card for size reference instead of a coin)

 

Key to the process is to first layout the LEDs face down on a highly sticky material, (I used double sided heatsink tape).

 This rough diagram shows the arrangement and connections, the LEDs in the drawing are rotated 32° for best pin alignment.

I start be directly soldering the the Data out and Data in pads of adjacent chips to lock in their positions, that soldering bare wire VDD and Ground buses.  I brought out the ground lead from the opposite end of the string top reduce chip connection clutter.

These parts have cooling issues when bunched together, more so with no copper mounting pads, best to limit the brightness.

Handle carefully, if flexed like a normal LED strip, data connection pads will break off the chips. Adding some sort of rigid backing would be important for wearable applications.

  Here's a short test of metronome patterns (my cheap camera poorly represents the colors)


 

A 25 element version seemed to function properly using wire-wrap gauge wire, with no bypass capacitors on the 50 mm long string.




Comments

Post a Comment

Popular posts from this blog

Hooking up the 6 + 1 Mic Array to the MaiX BiT

Image
The Risk-V chip on the MaiX BiT board also contains hardware FFT which should make it a respectable audio analysis board.  Sipeed offers a microphone array board with 7 mics and 12 RGB LEDs. Unfortunately the mic array, which SeeedStudio  indicates is for Dock/Go/Bit, there is no real provisions made for the newer BiT board. Included with the mics is a 10 pin ribbon cable for the Go board, and an unadvertised (not on sales page inventory) 5x2 "dupont" connector cable which directly connects between the back of the mic array (not pictured on the sales page) and the Dock board area with mic connection labels silk screened on the board. Some improvising is needed to hook up the BiT.  I offer 2 different solutions. The first that Seeed could help by throwing in a couple of replacement connector housings. Connection Method #1 (You might have to start with a larger housing and cut it down to size) The Seed OPL type for ...
Read more

Holographic Fans Getting Real Time HDMI Input

Image
 One of the technical leaders in so called 3D Holoographic LED Fans is Dseelab, in Sep 2019 they announced at an event the development of real time HDMI Video Input, it may be quite a while befiue it reaches the market.  Achieving this has been my holy grail, looking into FPGA based video processors and examining cartesian to polar code may no longer be necessary... Here's an interesting demo recently posted: Dseelab a leader in the "3D Holographic LED Fan" industry, has master-slave connections on their units, allowing them to be syncronized in an array, they also offer a programming API connecting though WiFi or with a wired serial connection to a PC.  The API supports remote update from the cloud and random play of 256 different media assets. The only other Holographic Fan maker offering a programming API and arrays for large image display is HYPERVSN of  Ireland.  The newest addition to the DseeLab line is their: 6 Blade 78cm, 960*960 res, ...
Read more

LED Driver Roundup

Image
LEDs being current, rather than voltage operated devices require special driver circuits for optimal performance.  While simple applications like an indicator light that might be run at a fraction of it's rated capability, a series current limiting resistor is sufficient.  High power application running at the edge of the LED's max current rating require active regulation to compensate for the negative temperature coefficients of the LED, (measurement techniques are discussed in this university lab paper .) Low power LEDs can be driven with simple series resistor current control when powered from a regulated power supply. The LED Load Line graph be low helps one select a standard resistor value to get the ballpark current setting with a 5 volt power source.  Find where your LED's color line intersects the desired current, then pick the closest resistance line below that intersection. (This graph is from LEDnique.com , a collection of basic articles on LEDs aime...
Read more