Design West Update: Intel’s Computer-Controlled Orchestra

It wasn’t the Blue Man Group making music by shooting small rubber balls at pipes, xylophones, vibraphones, cymbals, and various other sound-making instruments at Design West in San Jose, CA, this week. It was Intel and its collaborator Sisu Devices.

Intel's "Industrial Controller in Concert" at Design West, San Jose

The innovative Industrial Controller in Concert system on display featured seven Atom processors, four operating systems, 36 paint ball hoppers, and 2300 rubber balls, a video camera for motion sensing, a digital synthesizer, a multi-touch display, and more. PVC tubes connect the various instruments.

Intel's "Industrial Controller in Concert" features seven Atom processors 2300

Once running, the $160,000 system played a 2,372-note song and captivated the Design West audience. The nearby photo shows the system on the conference floor.

Click here learn more and watch a video of the computer-controlled orchestra in action.

Design West Update: Compilers Unveiled

IAR Systems announced Tuesday at Design West in San Jose, CA, that GainSpan selected IAR Embedded Workbench as its primary development tool chain for MCU drivers and next-generation chip. “By standardizing on IAR Systems’ embedded software development tool chain, GainSpan will more easily support a wide range of MCUs to communicate with their modules,” IAR publicized a in a release.

It’s an important aspect of a larger plan, IAR’s ARM Strategic Accounts Manager Mike Skrtic said. IAR has overall tool chain standardization goals aimed at giving designers’ more flexibility when choosing MCUs for product development.

Remember: IAR Systems is teamed with Renesas for the RL78 Green Energy Challenge, which is administered by Circuit Cellar and Elektor. Designers are challenged to transform how the world experiences energy efficiency by developing a unique, low-power application using the RL78 MCU and IAR toolchain.

In other compiler-related news, Microchip Technology announced Monday at Design West its new MPLAB XC C compiler line, which supports its approximately 900 microcontrollers. Microchip’s Joe Drzewiecki said the compilers reduce code size by about 35% and improve code execution speed by about 30%. But you can judge for yourself because Microchip offers 8-, 16-, and 32-bit free editions of MPLAB XC compilers. According to Microchip reps, they are” fully functional and have no license restrictions for commercial use.”

So, if you give MPLAB XC a try, let us know what you think!

Q&A: Dave Jones (Engineer, EEVBlog)

Are you an electrical engineer, hacker, or maker looking for a steady dose of reliable product reviews, technical insight, and EE musings? If so, Dave Jones is your man. The Sydney, Australia-based engineer’s video blog (EEVblog) and podcast (The Amp Hour, which he co-hosts with Chris Gammell) are quickly becoming must-subscribe feeds for plugged-in inquisitive electronics enthusiasts around the world.

Dave Jones: engineer, video blogger, and podcaster

The April issue of Circuit Cellar features an interview with Jones, who describes his passion for electronics, reviewing various technologies, and his unscripted approach to video blogging and podcasting. Below is an abridged version of the interview.

David L. Jones is a risk taker. In addition to jumping off cliffs in the name of product testing, the long-time engineer recently switched to full-time blogging. In February 2012, Dave and I discussed his passion for electronics, his product review process, and what it means to be a full-time video blogger.—Nan Price, Associate Editor

NAN: When did you first start working with electronics?

DAVE: The video story can be found at “EEVblog #54 – Electronics – When I was a boy…” I was very young, maybe six or so, when I was taking apart stuff to see how it worked, so my parents got me a 50-in-1Tandy (RadioShack) electronics kit and that was it, I was hooked, electronics became my life. And indeed, this seems to be fairly typical of how many engineers of the era got started.

By the time I was eight, I already had my own lab and was working on my own projects. All my pocket money went into tools, parts, and magazines.

The electronics magazine industry was everything back then before the Internet and communications revolution. I would eagerly await every issue of the Australian electronics magazines like Electronics Australia, Electronics Today International (ETI), Applied and Australian Electronics Monthly (AEM), Talking Electronics, and later Silicon Chip.

NAN: Tell us about some of your early projects.

DAVE: Given that it was over 30 years ago, it’s hard to recall I’m afraid. Unfortunately, I just didn’t think to use a (film) camera back then to record stuff, it just wasn’t something that you did as a kid. The family camera only came out on special occasions. So those projects have been lost in the annals of time.

My first big published magazine project was a digital storage oscilloscope (DSO) adapter for PCs, in a 1993 issue of Electronics Australia. I originally designed this in the late 1980s. (See “,

NAN: You have many interests and talents. What made you choose engineering as your full-time gig?

DAVE: There was no choice, electronics has been my main hobby since I can remember, so electronics engineering was all I ever wanted to do to. I’ve branched out into a few other hobbies over the years, but electronics has always remained what I’ve wanted to do.

NAN: The Electronics Engineering Video Blog—EEVBlog—is touted as “an off-the-cuff video blog for electronics engineers, hobbyists, hackers, and makers.” Tell us about EEVBlog and what inspired you to begin it.

DAVE: I’ve always been into sharing my electronics, either through magazines, via my website, or on newsgroups, so I guess it’s natural that I’d end up doing something like this.

In early 2009 I saw that (WordPress-type) blogs were really taking off for all sorts of topics and some people were even doing “video blogs” on YouTube. I wondered if there were any blogs for electronics, and after a search I found a lot of text-based blogs, but it seemed like no one was doing a video blog about electronics, like a weekly show that people could watch … So I thought it’d be fun to do an electronics video blog and blaze a new trail and see what happened.

Being fairly impulsive, I didn’t think about it much; I just dusted off a horrible old 320 × 240 webcam, sat down in front of my computer, and recorded 10 minutes (the YouTube limit back then) of whatever came into my head. I figured a product review, a book review, a chip review, and some industry news was a good mix … I’ve had constant linear growth since then, and now have a regular weekly audience of over 10,000 viewers and over 4 million views on YouTube. Not to mention that it’s now my full-time job.

The complete April issue of Circuit Cellar is now available. For more information about Dave Jones, his video blog, and podcast, visit and

Design West Update: Advanced 8-Bit MCUs

Is the 8-bit MCU dead? No. And if you take a look at Microchip Technology’s PIC16F(LF)178x family, it’s clear that it will be around for a long time to come.

Microchip Technology announced Monday from Design West in San Jose, CA, that it “expanded its 8-bit PIC16F(LF)178X midrange core MCU family to include advanced analog and integrated communication peripherals, such as on-chip 12-bit analog-to-digital converters (ADCs), 8-bit digital-to-analog converters (DACs), operational amplifiers, and high-speed comparators, along with EUSART (including LIN), I2C, and SPI interface peripherals.”

Microchip claims the low power consumption and advanced analog and digital integration make the MCUs (28- and 40-pin packages) well suited for lighting (LED), battery management, motor control, and more.

Check out the specs and more details at

Renesas RL78 Green Energy Challenge

Up for an international design challenge? It’s time for the Renesas RL78 Green Energy Challenge! Renesas has partnered with IAR Systems to deliver engineers a power-house combo of low-power devices and high-quality software. They’re steering a great, green revolution and are challenging you to transform how the world experiences energy efficiency by developing a unique, low-power application using the RL78 MCU and IAR toolchain. Succeed and win a share of $17,500 in Grand Prizes from Renesas! * The Renesas Grand Prize winner will also win a free trip to Renesas DevCon in October where winners will be announced.

But that’s not all. Earn additional prizes like developments tools, Pmods, Wi-Fi modules, embedded systems books, and more from Contest Partners through weekly prize drawings. Follow Renesas on Twitter and Facebook for weekly challenge questions from official Contest Partners. Weekly Partner Challenges, and the respective winners, will be announced every Monday throughout the competition.

So, do you have a great idea for a remote device that monitors pollution? What about a box collecting data on home power usage or an energy harvesting biometric design? Perhaps your grand plan is for a low power controller scavenging heat from an oven or furnace, a meter reading biomass parameters, or a braking system for a wind turbine? It’s up to you! Send us your best RL78 based ideas to help make the world a better place.

The Challenge starts March 26, 2012 and ends on August 31, 2012. Winners will be announced in October at Renesas’ DevCon 2012.

Hundreds of free RL78/G13 development kits (“RDK”s), loaded with IAR’s Kickstart edition, are being distributed to those who qualify. Click here to see if you qualify for a complimentary RDK!

*Prizes in U.S. dollars.

Circuit Cellar, Inc. and Elektor International Media is the Contest Administrator.


Weekly Elektor Wrap Up: Thermometer with Giant Display, AVR Software-Defined Radio Webinar, & More!

It’s time to review what our Elektor colleagues in The Netherlands, France, and beyond worked on and covered this week! As usual, they’ve been quite busy working in the Elektor lab, organizing webcasts, prepping for Design West, and assembling upcoming issues of Elektor magazine. The following is a wrap-up of some of the many things Elektor staffers covered and worked on this week.

Below is a video of a thermometer with a giant display.

The electromechanical display was recovered from a ’60s-era pinball machine.

The thermometer with a giant display

Using the display and some innovative programming techniques, it’s possible to build a water-temperature indicator a swimming pool. After the temperature appears on the 4″ reels, the circuit’s consumption decreases to zero. But the temperature display remains perfectly visible. You needn’t worry about batteries (dry or rechargeable), adjustments, or maintenance. (Published in Elektor issue 424, April 2012

Board for Elektor's thermometer with a giant display

On the event front, Elektor Academy and element14 have teamed up to bring you a series of exclusive webinars covering blockbuster projects from recent editions of Elektor magazine. Participation in these webinars is completely free! All you need to do is register via The “AVR Software-Defined Radio” webinar takes place Thursday, March 9, 2012. Click here for more information.

Elektor also reported some interesting electronics news this week. The items that will most interest Circuit Cellar readers are an Uninterruptible Power Supply in a Chip and a Python-Based Tool for Diagnosing Dead-Core Boards. is part of the Elektor group.

Electronics Engineering Crossword (Issue 261)

The answers to the crossword puzzle published in rCircuit Cellar 261, April 2012.


7. MANCHESTERENCODING—A form of BPSK [two words]

10. REBOOT—Restart

13. HASHTAG—The # label

15. DIRECTORY—File index

17. DAEMON—Takes place behind the scenes

18. FREEBASIC—Open-source programming language compiler

19. MALWARE—Bad code


1. PHASESHIFTKEYING—Transports data by altering a reference signal’s phase [three words]

2. FOURIERTRANSFORM—Changes a signal from the time domain to the frequency domain [two words]

3. ATTENUATON—Used to measure signal loss in dB

4. SHANNONTHEOREM—AKA, the noisy-channel coding theorem [two words]

5. BOOLEAN—Logic system named after George Boole

6. FREQUENCYMODULATION—Opposite of AM [two words]

8. COULOMBCOUNTER—Measures battery current [two words]

9. FOURTHGENERATION—4G [two words]

11. FIRSTQUARTILE—25th percentile [two words]

12. NORTONAMPLIFIER—Converts a current to a voltage. [two words]

14. HBRIDGE—Four switching components with the load in center

16. CODIFY—A way to organize

Issue 261: Cap-Touch Amp Design, RL78 Intro, Embedded Linux, & More

The April issue is now available. As usual, it comprises a wide variety of content: a capacitive-touch amplifier design, an intro to using the Renesas RL78 for low-power apps, info on sigma-delta modulators, Linux software development tools, mesh networking tips, an interview with Dave Jones (of The Amp Hour and EEVblog) and more.

One of Dave Jones's old projects from the '80s. It's a Veroboard construction with items from his junk bin (Source: D. Jones, CC261)

A portion of the PIC-based PodAmp schematic (Source: C. Denninger & J. Lichtenfeld, CC261)

You’ll also notice some changes this month to Circuit Cellar magazine and our website. They’re all for the better.

The magazine has an updated layout. We haven’t changed fonts or style, but we did add the imprint you can see on pages 6–7. Its purpose is to show you that we are an ever-growing international company dedicated to bringing you essential information on a variety of important advanced electronics topics.

I added our editorial calendar, as well as a brief summary of the content we have in queue, to page 2. The idea is to give you a clear idea of what we will cover and when you can expect it. Members frequently ask for this information, so it makes sense to make it easily accessible for everyone.

As for, well, you’ve likely watched it change slowly over the past few months. We did this purposely. We developed the site in stages so readers wouldn’t be burdened with dead links and redirects. So, what’s new about the site?

The layout is a bit different. A few things are quickly apparent. One, the site is markedly brighter and easy on the eyes. Two, we created three distinct columns that provide you with easy access to handy articles, digital downloads, and more (see below). Three, we’re tagging and categorizing all the content on our site. Thus, you’ll find targeting specific information to be uncomplicated and immediately gratifying.

What sorts of content can you expect? The old site was fairly static. We’d make several changes each month and we’d run a few viewable articles. Now we’re constantly posting relevant content of all sorts. This means you can rely on for all of your electronics engineering needs: DIY articles, engineering tips, industry news, product reviews, vendor information, issue previews, links to source code, and even job openings in electronics engineering and embedded design.

If you are constantly plugged in, you’ll find our website makes accessing your digital membership a cinch: just point and click to log in and download each issue! Plus, you can add our site to your RSS reader and read our content at your convenience (

We are not finished building In the coming weeks and months, we’ll enable more social interaction, post more videos, and broaden our areas of coverage. I suggest you visit our site each day to get your fix of embedded technology news and info. And please recommend the site to colleagues, friends, and others who have a passion for microcontrollers, programming, and everything else that’s “inside the box.”


Build a CNC Panel Cutter Controller

Want a CNC panel cutter and controller for your lab, hackspace, or workspace? James Koehler of Canada built an NXP Semiconductors mbed-based system to control a three-axis milling machine, which he uses to cut panels for electronic equipment. You can customize one yourself.

Panel Cutter Controller (Source: James Koehler)

According to Koehler:

Modern electronic equipment often requires front panels with large cut-outs for LCD’s, for meters and, in general, openings more complicated than can be made with a drill. It is tedious to do this by hand and difficult to achieve a nice finished appearance. This controller allows it to be done simply, quickly and to be replicated exactly.

Koehler’s design is an interesting alternative to a PC program. The self-contained controller enables him to run a milling machine either manually or automatically (following a script) without having to clutter his workspace with a PC. It’s both effective and space-saving!

The Controller Setup (Source: James Koehler)

How does it work? The design controls three stepping motors.

The Complete System (Source: James Koehler)

Inside the controller are a power supply and a PCB, which carries the NXP mbed module plus the necessary interface circuitry and a socket for an SD card.

The Controller (Source: James Koehler)

Koehler explains:

In use, a piece of material for the panel is clamped onto the milling machine table and the cutting tool is moved to a starting position using the rotary encoders. Then the controller is switched to its ‘automatic’ mode and a script on the SD card is then followed to cut the panel. A very simple ‘language’ is used for the script; to go to any particular (x, y) position, to lift the cutting tool, to lower the cutting tool, to cut a rectangle of any dimension and to cut a circle of any dimension, etc. More complex instructions sequences such as those needed to cut the rectangular opening plus four mounting holes for a LCD are just combinations, called macros, of those simple instructions; every new device (meter mounting holes, LCD mounts, etc.) will have its own macro. The complete script for a particular panel can be any combination of simple commands plus macros. The milling machine, a Taig ‘micro mill’, with stepping motors is shown in Figure 2. In its ‘manual’ mode, the system can be used as a conventional three axis mill controlled via the rotary encoders. The absolute position of the cutting tool is displayed in units of either inches, mm or thousandths of an inch.

Click here to read Koehler’s project abstract. Click here to read his complete documentation PDF, which includes block diagrams, schematics, and more.

This project won Third Place in the 2010 NXP mbed Design Challenge and is posted as per the terms of the Challenge.



Read for Updates/News from Design West, San Jose

Circuit Cellar and Elektor editors and staffers will attend Design West in San Jose, CA, from March 27 to 29. If you can’t make it to the conference, check daily for conference updates, news, and more!

Feed the latest posts from to your RSS reader! Doing so will keep you up-to-date on everything we post! Setting up the feed is simple.Add to your RSS reader and enjoy!

The Circuit Cellar/Elektor booth at ESC 2011 (San Jose, CA)

This year’s conference comprises seven summits at once: ESC, Android, Black Hat, DesignMED, LED, Sensors, and Multicore.

Members and clients are encouraged to stop by booth #2332 to chat with staff, subscribe to our magazines, grab free copies of the magazines, and check out our books. Readers should feel free to bring and pitch article proposals, book proposals, and project ideas!


Weekly Elektor Wrap Up: An Innovative ECG Patch, an Affordable Linux Computer, & an AVR Software-Defined Radio Event

It’s time for our weekly wrap up of Elektor news and content for Circuit Cellar members. As usual, our colleagues in Europe and beyond are always covering some cool embedded-related topics.

Let’s start with an interesting post about an innovative processor-based healthcare system: an intelligent patch capable of continuously monitoring heart activity. The design combines embedded and wireless technologies to measure, record, and transmit electrocardiogram signals:

The patch developed by the research labs Imec and Holst Centre and the Danish company Delta measures 3 ECG signals while a 3D accelerometer monitors physical activity. The captured data is processed by a microprocessor integrated in the patch and relevant information is transmitted wirelessly using the new Bluetooth Low Energy technology. Energy consumption is low enough to allow continuous operation during one week.

Click here to read the entire post.

Have you been reading Circuit Cellar columnist Bob Japenga’s articles on embedded Linux? If so, you’ll check out Elektor’s post about Raspberry Pi:

The board is based on a Broadcom BCM2835 SoC, which includes an ARM1176JZF-S 700 MHz processor, a VideoCore IV GPU and 128 or 256 MB of RAM is intended to run Linux kernel based operating systems. Selling for only 28 Euros the distributors’ websites have been overwhelmed by the demand and the first batch of 10,000 pieces was sold out in less than an hour.

The foundation plans to release two versions: Model A & Model B. Model A will have 128 MB RAM, one USB port and no Ethernet controller, while model B will contain 256 MB RAM, two USB ports and a 10/100 Ethernet controller.

Click here for the entire article. You can also read my recent post on Raspberry Pi. Check it out!

Lastly, consider attending the upcoming Elektor Academy webinar “AVR Software Defined Radio.” The webinar is scheduled for 3/29/12. Click here for more information. If you attend, be sure to let us know what you think!

Circuit Cellar and are part of the Elektor group.

Issue 261: Renesas RL78, Cap Touch, Synapse SNAP, & More!

Here’s a sneak peek at the projects and topics slated for the April issue of Circuit Cellar: Linux software development tools, DIY cap-touch, gain-controlled amplifier; color classification reader; start designing with the Renesas RL78 microcontroller; an introduction to sigma-delta modulators; RFI bypassing, with a focus on parallel capacitors; mesh networking simplified with SNAP technology; and more.


Clemens Valens introduces the Renesas Electronics RL78:

Click the image to link to the Renesas product page

Jeff Bachiochi takes a close look at Synapse Wireless SNAP technology:

Click the image to link to the Synapse-Wireless Kit webpage

Ed Nisley presents Part 2 of his article series “RFI Bypassing”:

The tracking generator output and spectrum analyzer input connect to adjacent PCB pads on the left of the SMD capacitor. Connecting the spectrum analyzer to the pad on the right side changes the measured self-resonant frequency.

The April issue will hit newsstands in late March.

Fundamental Amplifier Techniques with Electron Tubes

Want tips on designing electron tube amplifiers? Fundamental Amplifier Techniques with Electron Tubes might be the book for you. The author, Rudolf Moers carefully details the science of hollow-state design as applied to amplifiers and power supplies.

The book is an Elektor group publication. So, I asked tube amp aficionado Richard Honeycutt to provide an unbiased review the book. (I asked him to do this prior to taking him on as a columnist for audioXpress magazine.) He agreed, and here’s the review, which is also available in audioXpress April 2012:

Back in the 1950s and 1960s, if you wanted to learn about vacuum tube amplifiers, you could read the Radiotron Designer’s Handbook, a 1,500-page behemoth that covered all kinds of vacuum tube circuits that were known at the time, and also included abundant information on passive components as well. Or you could use the introductory material and example schematics in the RCA Receiving Tube Manual—much shorter and less expensive, and also far less comprehensive. Of course, it did include data on most tubes then being manufactured by RCA. If you just wanted to build your own amplifiers, but were not interested in designing, there was the Mullard  Circuits for Audio Amplifiers. For a more scholarly approach, you could check out an electrical engineering textbook such as Analysis and Design of Electronic Circuits by Paul Chirlian.

Now, however, things are different. Although some of these references can be found on the Internet, they are no longer up-to-date. Happily, however, Elektor recently published Fundamental Amplifier Techniques with Electron Tubes by Rudolf Moers, which presents a 21st-century perspective on the science of hollow-state design as applied to amplifiers and power supplies. Beginning with the principles of electron emission, the book progresses through standard vacuum tube varieties: diodes, triodes, tetrodes, and pentodes, after which it covers such general principles as frequency dependent behavior, non-linear distortion, noise, and negative feedback. The book concludes with a chapter on the construction of electron tube amplifiers. Unlike many of the earlier authors of books on electron tubes, Moers is not constrained by a need to cover such specialized tubes as pentagrid converters, or circuits specifically used in radio and TV receivers. Instead, he uses his 800 pages to discuss the physics underlying electron tube operation far more comprehensively than did any of his predecessors. He does this in a way that maximizes presentation of principles while minimizing unnecessary mathematics. In many cases, the physical explanations can be skipped over by those whose only interest is design methods. For the reader who does take advantage of the physical explanations, Moers’s inclusion of an eight-page listing/definition of mathematical symbols makes the explanations easy to follow.

The focus is by no means primarily on physics, however. None of the classic texts provides anything like so comprehensive coverage of the design and operation of half- and full-wave rectifier/filter circuits, or vacuum tube phase shifters, to mention a couple of examples.

Moers’s book assumes that the reader is familiar with basic DC and AC circuit theory, and therefore does not undertake the task of educating those who lack this understanding. The book is written from a scientific perspective in that, while mentioning the disconnect between measured and perceptual performance of an amplifier, the author makes no dogmatic claims about the relationship between the two, other than to opine that most of the “tube sound” results from harmonic distortion components that some people find pleasing to the ear. (Having followed this discussion for about four decades, your reviewer partially concurs, but believes that there are other elements involved as well.) The author lightheartedly introduces the quantity “cm2 of gooseskin/watt” as an example of a measurement of perceptual phenomena.

A consequence of Moers’ scientific approach is that specific catch phrases found in many amateur-oriented publications on tube technology are conspicuously absent. For example, it is difficult to read much about tube power amplifiers without noticing mention of the “Williamson amplifier.” This circuit was developed by D. T. N. Williamson and described in articles in Wireless World in April and May, 1947. It was unique in that it applied negative feedback around the entire amplifier, including the output transformer, thus reducing nonlinear distortion. Doing this required very careful design to ensure stability, including the elimination of interstage transformers such as the phase splitter transformer used in many prior designs.

Moers does not mention the Williamson amplifier by name, but the vacuum tube phase splitter design Williamson used is discussed in detail in the book, as is the method of designing a negative feedback loop encompassing the entire amplifier. Moers also gives a unique explanation of another pivotal power amplifier circuit: the ultralinear circuit invented in 1951 by Hafler and Keroes. It’s a case of content versus jargon.

In his otherwise excellent discussion of damping factor, Moers unfortunately makes the all-too-common error of ignoring the effects of voice coil  and lead wire resistance. He gives the common equation for damping factor: DF = (loudspeaker impedance)/(amplifier output impedance). Since the amplifier (modeled as an AC generator or Thevenin source), voice coil resistance, lead wire resistance, voice coil inductance, and reflected mechanical impedance form a series circuit whose actual damping is influenced by all elements, the lead wire resistance and voice coil resistance cannot be ignored. In fact, they can easily swamp the effects of the amplifier output impedance, at least for a pentode stage using negative feedback. However, Moers does not make the further error of insisting that the damping factor be a minimum of 100 as have some earlier authors. Using an 8-Ω speaker having about  6-Ω DC resistance, the effect of a combined output impedance and lead wire resistance less than 0.5 Ω is negligible.

Two shortcomings of Fundamental Amplifier Techniques with Electron Tubes are more or less linguistic. English may well be the only Germanic language in which the verb in a sentence is not at the end of the sentence required to come. Thus syntactical intrusions from the author’s native language sometimes make the text difficult for native English speakers. Also, Moers has chosen to use terminology that is probably not standard in English (at least American English) books on electronics. For example, he uses the term “ anode static steepness” to denote “transconductance” (also commonly called “mutual conductance.”) A common-cathode (or “grounded-cathode”) amplifier stage is called a “basic cathode” stage in Moers’ book.

These three small complaints pale in the face of the outstanding job the author has done in bringing together the theory, design, and practice of vacuum tube amplifiers in a single volume. Anyone who wants to go beyond the Heathkit level of tube amplifier understanding owes it to him/herself to buy and study this excellent volume.

If you’re interested purchasing the book or learning more about it, click here to visit the book’s webpage in the CC Webshop.

Fundamental Amplifier Techniques (by Rudolf Moers), audioXpress, and are Elektor group publications.


Q&A: Per Lundahl (Transformer Design)

Per Lundahl is a multitalented designer who runs one of world’s leading high-performance audio transformer manufacturing outfits, Lundahl Transformers, which is based in Norrtalje, Sweden. After graduating from the School of Physics at the Royal Institute of Technology in Stockholm, he worked as a computer consultant for Ericsson. It wasn’t until he decided to move out of the city that he joined his family’s business, which his parents started in 1958.

Per Lundahl, CEO of Lundahl Transformers

In the April 2012 issue of audioXpress magazine, Lundahl shares stories about the company’s focus and products. He states:

I design all our new transformers. Our audio market is divided into two segments, Pro Audio and Audiophile. The Pro Audio segment includes transformers for microphones, mic pre-amps, splitters, distribution amplifiers, and other studio equipment. The Audiophile segment is transformers for MC phono cartridge step-up and for tube and solid state amplifiers.

Our biggest selling products are two types of transformers for microphone preamplifier inputs. In the Audiophile domain, our tube amplifier interstage and line output transformers are popular.

We constantly develop new transformers based on the requests of our customers. Presently we are developing an auto-transformer for a Chinese company and an interstage/line output transformer for some European customers. The latter will probably be added to our range of standard transformers, available to everyone.

For the very fastidious audiophile, we are also introducing silver wire in some of our transformer types. Initially, the wire will mainly be in our high-end MC transformers, but depending on the response, it is possible that we will extend the silver wire product range.

You can read the entire interview in audioXpressApril, which is currently available on newsstands.

Tube amp transformers

audioXpress is an Elektor group publication.

Raspberry Pi: Is It for You?

Unless you’ve been locked in your lab or design studio for the past several weeks, you’ve likely heard about Raspberry Pi, which is a compact, affordable computer that has been creating a buzz on the ‘Net for some time now. The group behind the computer is the Raspberry Pi Foundation, which is a UK-based charity that has an ever-growing following of more than 52,000 followers on Twitter!

(Source: and The Raspberry Pi Foundation)

According to the Raspberry Pi Foundation, “The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It’s a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. We want to see it being used by kids all over the world to learn programming.”

The 85.60 mm × 53.98 mm × 17 mm Raspberry Pi weighs in at 45 g. It features a Broadcom BCM2835, including an ARM1176JZFS and a Videocore 4 GPU.

So, how can Circuit Cellar members use Raspberry Pi? Well, look at it in three ways. One, you can use it in a design of your own. Grab one and start building as soon as you can get your hands on one. Two, you can learn from the “story” of the Raspberry Pi Foundation—how it formed, how it works as a charity—and consider launching a tech foundation of your own. Three, you can design a low-cost embedded design platform or rapid prototyping solution—something distinguishable from the usual suspects of Arduino and mbed—and bring it to market.

In a recent post titled “What Are You Doing!?” at, Tessel Renzenbrink detailed an interview with Eben Upton, a founder and trustee of the Raspberry Pi Foundation. Tessel writes:

Raspberry Pi is grabbing the attention with a $25 computer ($35 for a networked model). In the middle of the storm is Eben Upton. Why is he convinced that a computer which has no casing, no keyboard, no HD and no screen, will be successful? It is time to put the question to him: ‘what are you doing?’

‘We wanted to have a computer especially for Python, and there is a great tradition of naming computers after fruit: like Apricot, Acorn and even today there are computers named after fruit. So Raspberry is following the line of a rich tradition with the Pi, and yes, we wanted this connection with Python. That is where the Pi comes in’, explains Eben when asked for the name Raspberry Pi. And why is it a charity that brings this computer to the market? ‘That all has to do with value creation’, Eben continues. ‘I’ve been involved in several start-ups and then you always end up with the question; how will this create value?’. ‘In this case I do not have to worry about creating value. I can concentrate on designing and producing the board. The Raspberry Pi can be seen as a ‘white label’ product. If there are people out there with a commercial idea for this product, they are more then welcome’.

The Raspberry Pi is a bare PCB board; no keyboard, no HD, no screen.. how will this product become successful? ‘Basically, there is no reason why a computer has to cost more than $50. The peripherals like a screen and keyboard and storage will create a higher price, but with the Raspberry Pi we have taken another route – a normal TV can be used as a screen’, comments Eben. ‘Combine that with a ‘charity shop’ keyboard for a few dollars and you have a full working system’. He further emphazises that ‘the Raspberry is specifically aiming at youngsters learning to program’.

And how about the Raspberry Pi being ‘the next big thing’ after Arduino? There are many hints in that direction on the Internet? ‘The Raspberry Pi is different from the Arduino. The Arduino is great for direct applications and there are dozens of programs available. The Raspberry Pi is a computer system – designed to work with a screen and keyboard, a completely different idea. You can even watch videos with this thing. What might be interesting is the possibility to use the Raspberry Pi as a host for the Arduino board – the combination of these two, resulting in low priced systems can be very interesting and useful’.

‘There is also a difference the flexibility and usability, adds Eben. We have chosen for Broadcom chips and they are not easy to get in the market, making it very difficult to call the Raspberry Pi an ‘open source’ project. We are hoping to take this development into the open source direction, but that will require a new design’.

Can designers use the Raspberry Pi for different applications? ‘Yes, no problem. There is plenty of I/O (I2C and UART) to start using it for whatever challenges you’.

The first batch of 10,000 Pi’s has now arrived from the factory – what will be the next step? ‘Another 10,000 we hope and that is all just the start of it…’

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