The Battery Is Part Of The Art

July 6, 2019 by Brian McEvoy 7 Comments

A work of art is appreciated for its own sake and we will never tire of seeing stunning circuits from microscopic dead-bugs to ornate brass sculptures. We also adore projects that share the tricks to use in our own work. Such is the case with [Jiří Praus] who made some jewelry and shared his templates so we try this out ourselves.

The materials include brass wire, solder, and surface-mount LEDs. Template design expects a 1206 light, so if you step outside that footprint, plan accordingly. The printable templates are intuitive and leverage basic wire jewelry making skills. Some good news is that flashing LEDs are available in that size so you can have an array of blinkenlights that appears random due to drifting circuits. Please be wary with RGB lights or mixing colors because red LEDs generally run at a lower voltage and they will siphon a significant chunk of a coin-cell’s power from a competing green or blue. How else can these be personalized?

[Jiří]’s charms are just the latest of circuits that capture our eyes and tickle our ears.

Building A Googie-Style Sign With The Help Of CNC

July 2, 2019 by Lewin Day 8 Comments

The Googie style was a major architectural trend of the post-war period in the United States. It remains popular to throwback to this style, and [Wesley Treat] got the job to create a sign in this vein for a local trailer motel (Youtube link, embedded below).

CNC tools make just about any job easier, and this one is no exception. The smooth curves of the sign were carved out of several sections of PVC sheet, and stacked up to form the body of the sign. These were then sanded, coated in putty, and given a lick of paint. Steps like these could likely be skipped in the interest of saving time, especially given that few will see those parts once the sign is installed. However, [Wesley] takes pride in his work, and the final piece is all the better for it. It’s also important for the piece to impress the client, not just the public.

The front of the sign is also produced in PVC sheet, and given a coat of paint with brush techniques used to create a faux-wood finish. Vinyl is then applied to the textual and graphical elements in order to create a colored backlit effect. The sign is lit with off-the-shelf LED strips, and the whole assembly is weather sealed to protect it from the elements.

The final product is a beautiful piece, harking back to the classic Googie aesthetic and serving as a testament to [Wesley]’s skills. It’s a great example of how easy it is to create great work with the right tools and the proper attention to detail. It also goes to show how great LEDs are for signage, whether you’re at the beach or the lab. Video after the break.

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Visualizing LEDs For More Efficient Pin Packing

June 19, 2019 by Kerry Scharfglass 1 Comment

The archetypal “blink an LED” is a great starter project on any platform, but once the bug takes hold that quickly turns into an exploration of exactly how many LEDs a given microcontroller can drive. And that often leads to Charlieplexing. A quick search yields many copies of The Table describing how many LEDs can be driven by a given number of pins but that’s just the most rudimentary way to describe it. Way back in 2013 [M Rule] developed a clever trick to describe the number of LED matrices which can be driven by a Charlieplexed array of a given size that makes this process much more intuitive. The post may be old, but we promise the method is still fresh.

[M Rule] was specifically looking to drive those big, cheap single color LED matrices which are often used to make scrolling signs and the like. These parts are typically a matrix of LEDs with a row of common cathodes and one of common anodes. Internally they are completely dumb and can be driven by row/column scanning, or any other way a typical matrix can be controlled. The question is, given known matrix sizes, how many can be driven with a a number of Charlieplexed LED drive pins?

The first step is to visualize the 1D array of available pins as a 2D matrix, as seen to the right. Note each numbered pin is the same on the X and Y, thus the black exclusion zone of illegal drive pin combinations slicing across the graph (you can’t drive an LED connected to one pin twice). The trick, if one were to say it resides in a single place, would be titling the axis anode and cathode, representing two “orientations” the drive pins can be put in. With this diagram [M Rule] observed you can simply drop a matrix into the array. If it fits outside the exclusion zone, it can be driven by those pins!

To the left is what this looks like with two 8×8 matrices, one connected between pins 1-8 and 9-16, the other connected between 9-16 and 1-8. This isn’t terribly interesting, but the technique works just as well with single LEDs and any size matrix, including 7-segment displays. Plus as long as an element doesn’t overlap itself it can wrap around the edges leading to some wild visuals, like 14 RGB LEDs on seven pins to the right.

The most extreme examples are pretty exotic. Check out [M Rule]’s post for the crown jewel; 18 pins to drive six 5×7 modules, six 7-segment displays, 12 single LEDs, and 18 buttons!

If this color coded diagram seems familiar, you may be remembering [openmusiclabs]’ excellent diagram describing ways to scan many of buttons. Or our coverage of another trick of matrix topology by [M Rule] from a few weeks ago.

LEDSpicer Is An Open Source Light Controller For Your Arcade Machine

June 13, 2019 by Lewin Day 8 Comments

In this day and age of cheap and easy emulation, it’s more tempting than ever to undertake a home arcade cabinet build. If you want to show off, it’s got to have a light show to really pull the crowds in. To make that easier, [Patricio] put together a software package by the name of LEDSpicer.

The project came about when [Patricio] was working on his Linux-based MAME cabinet, and realised there were limited software options to control his Ultimarc LED board. As the existing solutions lacked features, it was time to get coding.

LEDSpicer runs on Linux only, and requires compilation, but that’s not a huge hurdle for the average MAME fanatic. It comes with a wide variety of animations, as well as tools for creating attract modes and managing LEDs during gameplay. There are even audio-reactive modes available for your gaming pleasure. It’s open source too, so it’s easy to tinker with if there’s something you’d like to add yourself.

It’s a great package that should help many arcade builders out there. LEDs can be used to great effect on a cabinet build; this marquee is a particularly good example. Video after the break.

[Thanks to Guillermo for the tip!]

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Simple Trick For LEDs On Solderless Breadboards

June 9, 2019 by Ted Yapo 39 Comments

Sometimes the most useful hacks are also the simplest ones. A case in point is the LED and resistor assembly that [Skippy] recently posted on his blog. The idea is to solder up some pre-made indicators with integrated resistors to save space on the breadboard when prototyping — instead of four slots, you only use two per LED. This is about as easy a trick as you can imagine, but it has the hallmark of a classic hack: a high utility-to-work ratio.

The deluxe assembly uses a two-pin header as a base to plug into the breadboard. This, of course, could be optional since some breadboards have a memory for the widest pin previously inserted — using header pins may eventually make the slots a little flaky for smaller component leads. But, if you’re mostly using header pins in the breadboard anyway, this is a good way to avoid kinking the leads.

While there are LEDs available with integrated dropping resistors, building your own means you can use whatever LEDs you prefer — or simply have on hand — and adjust the resistor value for different voltages or to adjust the brightness. And for those of you who plug in LEDs without current-limiting resistors, we’re going to assume that you’ve thoroughly researched whatever is driving them and done the math to ensure they’re safe. Or not: they’re your LEDs after all.

We previously featured a no-solder breadboarding trick for SMD LEDs. What’s your favorite solderless breadboard hack? Let us know in the comments below.

Thanks to [Roboteernat] for the tip!

Teardown The Things You Love

June 3, 2019 by Brian McEvoy 2 Comments

This two-decade old blinkenlights project (YouTube link, and also below the break) would look at home among current $1 soldering kits except for a few key differences. Firstly, it has the teardown artist’s name on the back and comes from an era when DIY circuit boards really meant doing things yourself including the artwork, etching, and drilling. The battery holders are our favorite feature. Instead of being a part on a BOM, this board has some wire loops soldered in place and relies on a pair of venerable LR44 alkaline cells instead of the CR2032s we all enjoy today.

Given the age of the project, [Big Clive] is not revisiting his old masterpiece just for nostalgia, he is having to retrace his old circuit and do a teardown on his own work because the schematic was lost to time. We think there is value to revisiting old work like an archaeologist would approach an ancient necklace. Some of us used to comment our code religiously for fear that we would forget what went through our learning minds and need to be reminded of that rigor.

If you want another battery holder that doesn’t need a part number, check out one that leverages the semi-flexible nature of thin PCBs or fake the batteries altogether. Continue reading “Teardown The Things You Love” →

Animated Pixel Lamp Is A Must For Any Chiptuner’s Bedroom

June 2, 2019 by Lewin Day 5 Comments

Lamps are quite often simple things, designed to light an area and perhaps add a touch of style to a room. Of course, it’s 2019 now, and we don’t need to settle for just that. We can have wildly colored animated lamps if we want to! (French Youtube link, embedded below.)

The lamp in question is the work of [Heliox], who knows her way around an LED or two (hundred). In this build, a string of WS2812 addressable RGB LEDs are hooked up to an Arduino Mega brain. The LEDs are fitted into a round lamp body, with a rectangular diffuser for each one. This creates an attractive pixellated effect and gives the animations a charming 8-bit quality. A thin outer shell is 3D printed in white plastic to further diffuse the light. The top of the lamp rotates an internal potentiometer to control mode selection. There’s also a brightness knob on the bottom if things get a touch too intense.

It’s a tidy build that uses 3D printing and addressable LEDs to quickly and easily create a lamp with a fun retro aesthetic. We could imagine this making a great piece for a hip sitcom apartment. We fully expect to see similar lamps on sale in the next couple of years. Video after the break.

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