Pocket High Voltage Generator Becomes Great Test Tool

October 8, 2018 by Donald Papp 4 Comments

[The LED Artist] often found a need for a relatively high voltage (100 to 200 Volt) but low current DC power supply, and it turns out that a small HV generator that uses a single AA cell only took about an hour to make. The device ended up being a pretty handy tool for testing things like LED filaments (which have a forward voltage of over 60 V), or even neon and nixie tubes.

The device’s low current means that nixie and neon elements won’t light up very brightly, but they will light up enough to verify function and operation. [The LED Artist] reports that touching the output terminals of the generator only causes a slight tingling sensation.

Open-circuit voltage generated from a single AA cell is about 200 V, but that voltage drops rapidly under any kind of load. Even regular LEDs can be safely lit with the circuit, with less than a milliamp being supplied at the two to three volts at which most regular LEDs operate.

[The LED Artist] fit the device into a two-AA battery holder, with a single AA cell on one side and the circuit in the other, and says it’s one of the more useful tools they’ve ever made. LED filaments are fairly common nowadays, but if they intrigue you, don’t forget that [Mike Harrison] covered everything you need to know about experimenting with them.

ESP8266 Clock Puts Time In A Jar

October 6, 2018 by Tom Nardi 13 Comments

Ironically, with the wide availability of modular electronic components today, the hardest part of constructing your latest gadget might just end up being able to find a decent looking enclosure for it. Project boxes will only get you so far, and let’s be honest, they aren’t exactly the most attractive things in the world. But if you’re willing to think outside the box (get it?) there are some unconventional options out there that might fit the bill.

Take for example this ESP8266 clock by [ZaNgAbY] that’s housed in a glass pasta jar. With the addition of some window tint film for the LED display to shine through, the final result could nearly pass as modern art. Even if you don’t need an extra clock around the house, this same general principle could be used to create a slick-looking ticker for all sorts of information, from the weather to server uptime with just some adjustments to the code.

Inside the jar there’s six 8×8 MAX7219 LED matrix modules tacked together to create one long strip, with a NodeMCU board stuck to the back with double-sided tape. There’s also a DS3231 RTC module so the clock can keep halfway decent time, but depending on how aggressively you are willing to pull down the current time from NTP, that may or may not be required. A simple barrel jack is popped through the metal lid of the jar for power, and represents the only physical connection the internals have to the outside world.

For the next iteration [ZaNgAbY] is thinking of adding a temperature and humidity sensor, and a light sensor that can dim the LED display depending on the ambient light. While the environmental sensors will have to go on the outside of the lid if there’s any hope of pulling useful readings from them, the clear glass will allow him to keep the light sensor internal to the clock.

Believe it or not, this isn’t the first time we’ve seen somebody give their electronics the pickle treatment. We’ve previously played host to a server that “preserves” files in a Mason jar, as well as a gorgeous display of an iPod under glass.

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DIY Studio Lights To Improve Your Videos

September 25, 2018 by Lewin Day 22 Comments

It’s 2018, a full thirteen years since YouTube was founded. With an online sharing service up and running, and high-resolution cameras in just about every mobile phone, the production of video has been democratized. Sadly, for those citizens with eyes, the production of good video is not so widespread. What’s one thing you need for good video? Good lighting – and you can build it yourself.

This build from [DIY Perks] relies upon readily available components and uses simple build techniques accessible to the average maker. Using cheap LED strips (albeit photography-grade ones), along with off-the-shelf plastics and dimmer modules, it’s possible to build a light that preserves colour integrity while being lightweight, compact, and easy to use. The final product is remarkably elegant – at a glance it could be a commercial product. Nifty tricks like daisy chaining the power supplies and combining different spectrum LEDs for better control add to the functionality.

Overall, it’s a build that does take some time, but it could easily be completed in a weekend and the results are top notch. It’s not the first lightbox build we’ve seen here, either. Video after the break.

[Thanks to Keith O for the tip!]

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World’s Smallest LED Blinky

September 23, 2018 by Mike Szczys 21 Comments

[Mike Harrison] is known for incredibly tiny soldering. Now he’s claiming a “world’s smallest” in the form of a stand-alone LED blinker, and we think he’s got the record.

He brought it along with him to Friday’s Beagleboard Bring-a-Hack, and we got a close look at the diminutive assembly. The project was dreamed up when [Mike] saw an announcement from Seiko about a new supercapacitor in a tiny package (likely the CPH3225A giving the blinky a footprint of 3.2 x 2.5 mm). With that in hand he added a PIC 10f322 microcontroller in a SOT23 package, an 0603 smoothing capacitor, and an SMD LED.

Blinky net to a metric ruler

US Quarter for scale (ruler is metric)

Charging jig doubles as a carrying case

With such a tiny package, the trickiest part is figuring out how to charge that supercap. [Mike] used a drill and hand files to make a square hole in a CR2032 battery holder to serve as a jig. The bottom of the supercap rests against the battery as a pogo pin makes the second connection to a terminal on the side of his assembly. It charges quickly and will happily blink away for about six minutes after charging.

Mike set out to make two of these, but dropped the second supercap when at his workbench to be forever lost in the detritus common to every electronics workshop. When he first pulled it out at the meetup we were on a rooftop terrace and we were more than a bit concerned that this would just blow away. How do you begin to fabricate such a tiny assembly? He used UV cured epoxy to glue them together first, then somehow completed the soldering by hand!

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Bixel, An Open Source 16×16 Interactive LED Array

September 12, 2018 by Tom Nardi 10 Comments

The phrase “Go big or go home” is clearly not lost on [Adam Haile] and [Dan Ternes] of Maniacal Labs. For years they’ve been thinking of creating a giant LED matrix where each “pixel” doubled as a physical push button. Now that they’ve built up experience working on other LED projects, they finally decided it was time to take the plunge and create their masterpiece: the Bixel.

Creating the Bixel (a portmanteau of button, and pixel) was no small feat. The epic build is documented in an exceptionally detailed write-up on the team’s site, in addition to the time-lapse video included after the break. [Adam] tells us the Bixel took around 100 hours of assembly, and we don’t doubt it. This is truly one of those labors of love which is unlikely to be duplicated, though all of the source files for both the hardware and software are available if you’re feeling brave enough.

The write-up contains a lot of fascinating detail about the design and construction of the Bixel, but perhaps the least surprising of all of them is that the final product ended up being very different from what they originally envisioned. The plan was to simply use lighted arcade buttons in a 16×16 grid, as they were purpose-built for exactly what the guys had in mind. But when they priced them out, the best they could do was $2 a pop. That’s $500 for just the buttons alone, before they even got into the enclosure or electronics. Like any good hackers, [Adam] and [Dan] decided to ditch the ready-made solution and come up with something of their own.

In the end, they cut the individual LEDs out of RGB strips, and soldered them down to their custom designed 500mmx500mm PCB. To the sides of each section of strip are two tactile switches, and above is a “sandwich” made of laser cut acrylic. The sheet closest to the LEDs has a 25mm hole, the top sheet has a 20mm hole, and between them is a circle of acrylic that acts as the “button”. Once it’s all screwed together, the button can’t fall out of the front or move from side to side, but it can be pushed down to contact the tactile switches.

To wire it all up they took a cue from the DIY keyboard scene and used a Teensy, some 595 shift registers, and 256 1N4148 diodes. A Raspberry Pi running their Python framework does the heavy computational lifting, leaving the Teensy to just handle talking to the hardware. Overall it’s a fantastic design to emulate if you’re looking to create large arrays of buttons on the cheap; such as whenever you get around to building that starship simulator.

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Less Is More: A Micromatrix Display In A Square Inch

September 12, 2018 by Al Williams 7 Comments

In your living room, the big display is what you want. But in an embedded project, often less is more. We think [bobricius] will agree since he submitted a tiny 4×5 LED display into our square inch challenge. The board features an ATtiny CPU and twenty SMD LEDs in a nice grid. You can see them in action, scrolling to some disco music in the video below.

There is plenty of room left in the CPU for bigger text strings — the flash memory is just over 10% full. A little side-mounted header makes it easy to program the chip if you want to change anything.

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LED “Candle” Gets The 555 Treatment

September 5, 2018 by Tom Nardi 29 Comments

Regular readers may recall we recently covered a neat Arduino trick that allowed you to “blow out” an LED as if it was a candle. The idea was that the LED itself could be used as a rudimentary temperature sensor, and the Arduino code would turn the LED on and off when a change was detected in its forward voltage drop. You need to oversample the Arduino’s ADC to detect the few millivolt change reliably, but overall it’s pretty simple once you understand the principle.

But [Andrzej Laczewski], like many of our beloved readers, feels the Arduino and other microcontrollers can be a crutch if used exclusively. So he set out to replicate this hack with that most cherished of ICs, the 555 timer. In the video after the break, he demonstrates his “old-school” LED candle for anyone who thinks the only way to control an LED is with digitalWrite.

Not to say it’s easy to replicate the original Arduino project with a 555, or that it’s even practical. [Andrzej] simply wanted to show it was possible, which is something we always respect around these parts. He goes into great detail on how he developed and tested the circuit, even including oscilloscope screenshots showing how the different components work together in real-time. But the short version is that a MOSFET is used to turn the LED on and off, a comparator detects change in the LED’s voltage drop, and the 555 is used to control how long the LED stays off for.

Ever the traditionalist, [Andrzej] wrapped up this build by etching his own PCB using a variation of the classic laser toner transfer method. If this all looks a bit too much like Black Magic to you, there’s no shame in sticking with the Arduino version. At 1/20th of the parts count, and with no calibration required, who’s to say which version is “simpler”.

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