FDIM 2012: The YADI micropower digital interface

Next in our tour of projects from the Four Days In May event at the Dayton Hamvention is an innovative radio-to-computer interface.

The YADI rig-to-computer interface prototype

The unique feature of YADI, Yet Another Digital Interface, is a micropower VOX circuit. This lets it sip power while waiting for a signal, where other interfaces are less battery-friendly. The secret is that the VOX amplifier is biased in “class E”, according to its designer, Dana Browne AD5VC. (It is possible he meant class C, since class E amplifiers are tuned and a VOX amp is broadband.)  That means that the amp uses no bias current when there is no signal. Its biasing also causes it to rectify the input, eliminating the need for an additional rectifier. The quiescent current is less than the self-discharge current of a 9V battery. In other words, the battery loses more energy sitting on a shelf than this interface needs to keep idle.

Dana, with Jim Giammanco N5IB, designed it with an eye towards emergency communications, particularly after hurricanes in their home state of Louisiana. It is designed to interface any radio and to any computer sound card, to support the many digital modes available today.

A kit version of the interface is being produced by the Baton Rouge Amateur Radio Club. The kit version was also on display at FDIM, but unfortunately, my photos of it did not come out. Suffice it to say that the kit includes a good-looking PCB, features easy through-hole assembly, and fits in a mint tin. The price is $35.

Unfortunately, I can’t find a link for the kit, other than some copies of the manual on a file sharing site. The BRARC web site is a vacant placeholder, and Google turns up no other leads. I hope this worthy kit becomes available soon and gets the publicity it deserves.

FDIM 2012: N8WE’s CW transceiver

A few weeks ago, I went to the Four Days In May event at the Dayton Hamvention, and brought back some pictures of the cool projects I saw.

N8WE's 200 mW CW transceiver

Glenn Hazen, N8WE, brought his 20 meter transceiver project to show-and-tell night. The radio’s receiver uses a Softrock Lite II downconverter with a laptop running a software-defined-radio (SDR) application. The transmitter is a 200 mW Morse code transmitter. That’s the code key on the right.


FDIM 2012: HamOS

A few weeks ago, I went to the Dayton Hamvention and the accompanying QRP event, Four Days In May (FDIM). QRP-ARCI always puts on a good program for FDIM, with a full day conference on Thursday, the day before Hamvention opens, and evening events Thursday, Friday, and Saturday.

Among the evening events are a show-and-tell night and a building contest night. Show-and-tell is open to anyone to bring a QRP-related project to share, whether finished or work-in-progress. The building contest has had varying rules over the years, but this year it had several categories, including kit-built radios, scratch-built radios, and station accessories. Judging was by audience ballot.

I forgot about show-and-tell night and regretted it. The FPGA morse code keyer would have fit right in.

I took some photos and notes from the evening events and will be sharing them over the next few weeks.

HamOS demonstration

First up is HamOS. Rich Gordon KD0BJT and Brady AC0XR were demonstrating this Linux-based operating system and handing out CD-R’s as fast as they could burn them. HamOS is a GNU/Linux distribution focusing on ham radio, with a variety of radio applications pre-installed. I can’t find a download link for HamOS, but hopefully that will be rectified soon.

Rich was lucky enough to get the “BJT” (Bipolar Junction Transistor) acronym in his call — and it looks like it is sequentially assigned, not vanity!

Rich and Brady also produce the lowSWR podcast, to which I have just subscribed.

SMT Soldering – It’s Easier Than You Think

Front page of "SMT Soldering: It's Easier Than You Think"Soldering Is Easy was a great starter, and now here’s a sequel: SMT Soldering – It’s Easier Than You Think.  Greg Peek and Dave Roberts put together a great little comic book that teaches the art of soldering tiny SMT components. After reading it, you will be ready to tackle chip resistors, SOT-23’s, and SOIC’s with confidence.  (You might also like to take a look at Skywired’s own tutorial on soldering SMT ICs.)

The comic book is licensed CC-BY-SA (Creative Commons Attribution Share Alike), so everyone is free to pass it on.

(Via MightyOhm.)

Cool open source hardware demos from OHS 2011

The Open Hardware Summit closed with an evening reception, with hors d’oeuvres tables tucked in amidst dozens of demos strewn around a large room at NYSCI. From an Ethernet-connected Arduino to a visual musical instrument, here are a few that caught my eye.

First up was the Nanode from Wicked Device. This board is an Arduino clone with built-in Ethernet. It would make a great platform for any control tasks that needed to interact with other Internet-enabled devices.

Nanode PCB Nanode concept slide

Right around the corner, an RC car was racing around the floor under the control of a subtly gesturing Jeremy Blum and his SudoGlove.

Jeremy Blum's SudoGlove SudoGlove explanatory slide

This curious device is titled “EaTheremin”. The forks had circuitry concealed inside the conductive handles. When one ate with them, current flowed from tines to handle via the diner’s body, causing a variable pitch to be emitted by a nearby speaker. I have to admit that I don’t quite get it, but I can appreciate the creativity of the EaTheremin’s inventor.


LittleBits had a table with their long-awaited magnetic circuit construction toy. The idea is to connect a series of small circuit boards to build interesting circuits. The boards hold themselves together with magnets, and keying in the plastic fittings at each end mean that incompatible components cannot connect to each other.  LittleBits founder Ayah Bdeir is one of the OHS organizers.

littleBits boards littleBits in use

The Learning Pet is a cute robot that augments educational games for children, developed by Erin Kennedy, better known as robotgrrl. The Pet can pivot, flap its wings, and change its expression in synchrony with events in a computer game.

Finally, Ryan Raffa’s RhythmSynthesis musical instrument was always surrounded by a crowd. By placing colored geometric shapes on the lightbox, one can compose repeating rhythm tracks. The color of each shape sets the pitch, the area selects the octave, and the outline, position, and possibly the rotation of the shape change other aspects of the sound. The sounds from each shape are played as if by an old-fashioned radar beam sweeping out a circle under the light table. Ryan developed RhythmSynthesis for his MFA in Design Technology, so plenty of details are in his thesis paper.

OHS attendees enjoying RhythmSynthesis Ryan Raffa demonstrating RhythmSynthesis

Here is a video of RhythmSynthesis in action, from the RhythmSynthesis web site:

These are but a few of the many tables at the reception, all with abundant creativity.

Open Hardware Summit 2011

Last week I took a trip to New York to attend the Open Hardware Summit. The talks were outstanding, and it was great to be in a crowd of extraordinarily creative people. While the open hardware world has its share of engineers, both amateur and professional, it also has artists, which makes for some interesting fusion.

Furthermore, the presentation skills of the speakers ranged from good to outstanding. It was a pleasant shock to watch one excellent talk after another. I must have been lulled into complacency by having seen too many boring talks at scientific conferences.

The Summit was held at the New York Hall of Science, which two days later hosted Maker Faire. As I walked down the street from the train station to the museum, I knew I was getting close when I saw these over the trees. That’s a Mercury and a Gemini capsule perched high on their boosters.

Rockets at the New York Hall of Science

Why the Hall of Science, one might ask? Eric Siegel, the Director and Chief Content Officer, welcomed us to the conference by explaining that NYSCI is about getting people interested in science, and he sees the open hardware movement as doing the same.

The keynote talk was from 4/5 of the Arduino team, who were entertaining and engaging speakers. A few memorable quips:

  • (When starting an open hardware business) “Hire a lawyer. You don’t know why but she does.”
  • “If you have a company with 5 people in 3 countries, you are a multinational corporation.”
  • (On the popularity of names ending in -duino) “We named the Arduino after our favorite bar. … The worst one was one morning when I found in my e-mail an announcement of a board called “Sanguino”. If you get the accents right, in Italian, that means ‘I am bleeding’.”

Bunnie Huang (of Chumby fame) gave a great talk on the end of Moore’s Law and what he sees as the future of open hardware. Moore’s law drives a very short market cycle for new designs, which means that by the time an individual hacker can build something interesting, it has been obsoleted by products from big corporations. In places like Shenzhen, though, the use of trailing-edge technology means small shops can innovate and still be competitive. Once Moore’s law runs into fundamental physical limits, Bunnie believes market cycles will slow and small innovators participating in the open hardware world will be able to compete more and more effectively with the big guys.

Bunnie was the first presenter to use his own hardware on stage.  He funneled his presentation through NeTV, an HDCP video overlay board. Bunnie had it set up so that people in the audience could text or tweet messages, in real time, to a scrolling banner at the top of his slides.

At lunch, OpenROV‘s Eric Stackpole and David Lang took up a strategic position next to the catering line with some of their underwater robots.

Open-source underwater robots

After lunch were more great talks. Surprising to me was the talk by Bruce Perens, the founder of the Open Source Initiative and one of the key players in the emergence of the widely-used open source software licenses used today. I thought he would have something to say about hardware licensing, but instead he talked about the ham radio satellites and what AMSAT and TAPR have done to develop and release open-source hardware designs.

James Bowman followed up with a great talk about the Gameduino, a board that can be used to play video games with an Arduino or other small microcontroller. His talk was about the development of Gameduino, which went from Kickstarter to a shipping product in three months. More than demonstrate his product, James used it as the sole device for presenting all of his slides. Here’s a Gameduino, as seen on a Gameduino:

The Gameduino uses James’s impressive J1 Forth CPU as part of its hardware. The J1 is on my list of things to try out.

Bryan Newbold gave an insightful talk about the economics of small-quantity price breaks. Being at Octopart, Bryan has access to a massive component price database, which he used to illustrate a number of points about small-run manufacturing, as is typical for an open source hardware startup. One of his most striking slides was this, which illustrates the effects of the hidden costs of various funding sources. In order to get the same cost per unit if selling 175 units with cash funding, a startup might have to sell 5000 units with Kickstarter funding. That’s a sizeable difference, and it’s caused by the interaction of quantity price breaks with the direct and indirect costs of various sources of funding.


Mitch Altman brought the plenary session to a close with a talk about his experiences turning the TV-B-Gone into a product. Mitch is an outstanding and entertaining speaker. One of his gems: “Hi, I’m Mitch Altman. I turn off TV’s for a living, and I LOVE MY JOB.”

The day finished with cocktails and demos from dozens of hackers and makers. I’ll have more on the creative things I saw there in my next post.

Want to share your thoughts about open source hardware? Were you at OHS? Comments are welcome!

Soldering is Easy comic book is now in 12 languages

Soldering Is Easy cover, English versionThe Soldering is Easy one-page comic has grown to an eight-page comic book, and it’s available in 12 languages! Mitch Altman, Andie Nordgren, and Jeff Keyzer created the original, and the translations were done by volunteer translators. It’s a great idea and well worth a read.

Here is every translation so far, all from Jeff’s MightyOhm blog:

Soldering is Easy (English)


Soldering is Easy (Simplified Chinese)

Solder É Fácil (Portuguese)

Menyolder Itu Gampang (Indonesian)

Soldar es Fácil! (Spanish)

… — .-.. -.. . .-. .. -. –. .. … . .- … -.– (Morse code)

Soldering is Easy (Japanese)

Οδηγός Για Εύκολη Συγκόλληση (Greek)

Löten ist einfach (German)

Souder c’est Facile (French)

Soldering is Easy – Traditional Chinese

Lutowanie Jest Proste (Soldering is Easy – Polish Translation)

Thanks, Mitch, Andie, Jeff, and translators for your great work!