PixelBrite is an LED wall/coffee table done right

pixelbrite

The scope of this project is almost as jaw-dropping as the cost of the parts. [LeoneLabs] calls the project PixelBrite. It’s a highly-polished modular RGB LED panel system, and he’s not keeping it a secret. We think it’s reasonable to call the build documentation mammoth. If you’re a fan of fast-motion assembly videos he’s got you covered there as well.

It’s interesting to compare this build to some of the Daft Punk tables from years back. It shows how economies of scale in the hobby electronics industry have helped new and affordable products to emerge. For instance, this offering is a 10×10 grid which is outside of the normal 8 pixel wide orientation dictated by 8-bit microcontrollers. The reason for the change is that this doesn’t use a matrix built with point-to-point soldering. It uses a string of RGB pixels (WS2801).

The enclosure is also a thing of beauty. The dividers that make up each cell are laser cut foam board. This makes the joints very tight to prevent light from leaking into the next cell. The housing is acrylic held in place by an aluminum rail system. Need more than one panel? No problem, a single connector chains one panel to the next. But we did mentioned the cost of materials. Unassembled you can expect to drop over five hundred bones for the pleasure of seeing this thing blink.

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LED retrofit for vintage edge-lit numeric display modules

edge-lit-led-retrofit

This single digit display is an old edge-lit module that [Ty_Eeberfest] has been working with. The modules were built for General Radio Company and have a really huge PCB to control just one digit. [Ty’s] modules didn’t come with that driver board, so he was left with the task of controlling an incandescent bulb for each digit. After a bit of thought he figured it would be much easier to just replace the edge-light bulbs with a set of LEDs.

We’ve seen these exact modules before, referenced in a project that created an edge-lit Nixie tube from scratch. Each digit in the display is made from a piece of acrylic with tiny drill holes which trace out the numerals. The acrylic is bent so that the edge exits out the back of the module where it picks up light from the bulb. [Ty] laid out his circuit board so that each LED was in the same position as the bulb it was replacing. As you can see, his retrofit works like a charm.

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CuteUino: Only use the parts of the Arduino that you need for each project

CuteUino

[Fran’s] been working on her own version of the Arduino. She calls it CuteUino for obvious reasons. The size of the thing is pretty remarkable, fitting within the outline of an SD card. But that doesn’t mean you won’t get the power that you’re used to with the device. She’s broken it up into several modules so you can choose only the components that you need for the project.

The main board is shown on the right, both top and bottom. It sports the ATmega328p (it’s hard to believe we could make out the label on the chip package in the clip after the break) in a TQFP-32 package soldered to the underside of what she calls the Brain Module. You can also see the extra long pins which stick through from the female pin headers mounted on the top side of the board. Inside of these pin headers you’ll find the clock crystal, status LEDs, and a capacitor. The other module is an FTDI board used to connect the AVR chip to a USB port.

You’ll definitely want to check out her prototyping post for this project. She uses a very interesting technique of combining two single-sided boards to make a 3-layer PCB. The side that was not copper clad is fitted with copper foil by hand to act as a ground plane for the vias. Neat!

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Prototyping a modular LED matrix

led-matrix-modular-prototype

[Will] was toying with the idea of creating a scrolling LED marquee to display messages as his wedding in May. But you’ve got to crawl before you can walk so he decided to see what he could do with the MAX7219 LED driver chips. They do come in a DIP package, but the 24-pin 0.1″ pitch chip will end up being larger than the 8×8 LED modules he wanted to use. So he opted to go with a surface mount part and spun a PCB which makes the LEDs modular.

These drivers are great when you’re dealing with a lot of LEDs (like the motorcycle helmet of many blinking colors). Since they use SPI for communications it’s possible to chain the chips with a minimum of connections. [Will] designed his board to have a male header on one side and a female socket on the other. Not only does it make aligning and connecting each block simple, but it allows you to change your mind at any time about  which microcontroller to use to command them. For his first set of tests he plugged the male header into a breadboard and drove it with an Arduino. We hope to hear back from him with an update when gets the final device assembled in time for the big day.

Adding a Bluetooth terminal to your router

bluetooth-router-terminal

This image shows an Android tablet monitoring the terminal of a router via Bluetooth. It makes it a snap to tweak your router from a multitude of devices as long as you’re within range (usually BT works up to about 30 feet or so). The only part that [Yohanes] needed to pull off the hack was a Bluetooth module which he picked up for a few dollars.

All routers will have serial connections somewhere on the board. His model (Asus RT-N16) even had the GND, RX, TX, and VCC pads labeled. He soldered a SIL pin socket to the port which accepts the pin header from the Bluetooth module. Before plugging that in he had to issue a few commands to the device to get it using the same baud rate and settings as the router’s serial port. With that taken care of he can now wirelessly monitor and control the device via the serial terminal.

The one issue which he did encounter is that the module is slower to boot than the router. This means that at power-up you will not see anything on the terminal until the router has already started to load the Linux kernel. If you don’t plan on doing any bootloader hacks this shouldn’t make any difference.

Kilonode: how to test a huge Xbee mesh network

So let’s say that you’re a developer on the Xbee team. You need to test the extremes of what the RF radio modules can do when in a large network. But in addition to numerous nodes, you also need to test the effects of distance on the radios. Since it’s not reasonable to distribute hundreds of the devices (each with their own power source) throughout town, you build a test setup like the 1 kilonode Xbee rig which the project manager, [Jared Hofhiens] is showing off.

He’s holding one blade from the rack-mounted system. Each of those squares is an Xbee module, there’s 32 etched onto the board. On the edge furthest from him there are a set of connectors which mate with the rack connectors, hooking the blade up to a set of terminal servers. These servers allow developers to ssh into individual modules. On the near side of the blade there’s a set of attenuation adjustment circuits. They allow adjustments of 0-40 dB of attenuation in 10 dB increments to adjust how strong the RF signals are, simulating distance between modules.

Thirty-two of these cards are mounted in the three racks seen above to make up the 1024 module node. We really appreciate this look behind the scenes and think you’ll enjoy the video tour after the break. If it leaves you wanting more check out how one company builds cloud storage. Continue reading “Kilonode: how to test a huge Xbee mesh network”

DIY breadboard modules for easy prototyping

[Rajendra] got tired of building the same basic circuits time and again on the breadboard. He decided to build some simple, modular circuits on protoboard and make them easy to interface with the breadboard. As you can see, he ended up with seven modules that make prototyping faster and easier.

At first glance some might not seem all that beneficial. For instance, making a board for an 18-pin PIC microcontroller into a single-in-line form factor would seem like you’re actually wasting breadboard space when compared to the DIL package of the chip. But consider that the oscillator and its capacitors, reset button, and programming header are also on the breakout board and will not have to be built in place. There are also several I/O boards, one with five buttons, another with an LED bar graph, and a set of LEDs with a SIL resistor package on-board. These modules can be plugged into a breadboard and wired up with jumper wires, or connected directly to the same rows as the microcontroller module.