About C. J. Abate

C. J. Abate is Circuit Cellar's Editor in Chief. You can reach him at cabate@circuitcellar.com and @editor_cc.

IR Remote Control Testing (EE Tip #119)

On the Internet you can find them in all shapes and sizes: circuits to test remote controls. Here I describe a simple and cheap method that is not that well-known.

This method is based on the principle that an LED does not only generate light when you apply a voltage to it, but also works in the opposite direction to generate a voltage when light falls on it. Within constraints it can therefore be used as an alternative for a proper phototransistor or photodiode. The major advantage is that you will usually have an LED around somewhere, which may not be true for a photodiode.

IR remote tester

IR remote tester

This is also true for infrared (IR) diodes and this makes them eminently suitable for testing a remote control. You only need to connect a voltmeter to the IR diode and the remote control tester is finished. Set the multimeter so it measures DC voltage and turn it on. Hold the remote control close to the IR diode and push any button. If the remote control is working then the voltage shown on the display will quickly rise. When you release the button the voltage will drop again.

However, don’t expect a very high voltage from the IR diode! The voltage generated by the diode will only be about 300 mV, but this is sufficient to show whether the remote control is working or not. There are quite a few other objects that emit IR radiation. So, first note the voltage indicated by the voltmeter before pushing any of the buttons on the remote control and use this as a reference value. Also, don’t do this test in a well lit room or a room with the sun shining in, because there is the chance that there is too much IR radiation present.

To quickly reduce the diode voltage to zero before doing the next measurement you can short-circuit the pins of the diode briefly. This will not damage the diode.—Tom van Steenkiste, Elektor, 11/2010

Want tips about testing power supplies? We’ve got you covered! EE Tip #112 will help you determine the stability of your lab or bench-top supply!

Arduino-Based DIY Voltage Booster (EE Tip #117)

If your project needs a higher voltage rail than is already available in the circuit, you can use an off-the-shelf step-up device. But when you want a variable output voltage, it’s less easy to find a ready-made IC. However, it’s not complicated to build such a circuit yourself, especially if you have a microcontroller board that’s as easy to program as an Arduino. And this also lets you experiment with the circuit so you can get a better understanding of how it works.

Source: Elektor, April 2010

Source: Elektor, April 2010

No surprises in the circuit—a largely conventional boost converter. The MOSFET is driven by a pulse width modulated (PWM) signal from the microcontroller, and the output voltage is measured by one of the microcontroller’s analog inputs. The driver adjusts the PWM signal according to the difference between the output voltage measured and the voltage wanted.

We don’t have enough space here to go into details about how this circuit works, but it’s worth mentioning a few points of special interest.

The small capacitor across the diode improves the efficiency of the circuit. The load is represented by R3. The components used make it possible to supply over 1 A (current limited by the MSS1260T 683MLB inductor from Coilcraft), but maximum efficiency (89%) is at around 95 mA (at an output voltage of 10 V). To avoid damaging the controller’s analog input (≤5 V), the output voltage may not exceed 24 V. For higher voltages, the values of resistors R1 and R2 would need to be changed.

The MOSFET is driven by the microcontroller, which is nothing but a little Arduino board. The Arduino’s default PWM signal frequency is around 500 Hz—too low for this application, which needs a frequency at least 100 times higher. So we can’t use the PWM functions offered by Arduino. But that’s no problem, as the Arduino can also be programmed in assembler, allowing a maximum frequency of 62.5 kHz (the microcontroller runs at 16 MHz). To sample the output voltage, a frequency of 100 Hz is acceptable, which means we can use Arduino’s standard timers and analog functions. The Arduino serial port is very handy: we can use it for sending the output voltage set point (5–24 V) and for collecting certain information about the operation. Thanks to the Arduino environment, it only took about half an hour to program. Software is available. — Clemens Valens (Elektor, April 2010)

PCB Design Guidelines (EE Tips #113)

Designing a matching printed circuit board (PCB) can be a challenge for many electronics enthusiasts. To help ease the process, Circuit Cellar and Elektor editors compiled a list of tips for laying out components, routing, and more.PCB1

  • When compactness is not a major consideration and the boards will be assembled by hand, through-hole components are the better choice. In this case you can use the pins of these components as “vias.”
  • On the other hand, surface-mount components can save a whole load of drilling on self-made PCBs. They make it simpler to achieve objectives such as minimum length for traces , minimal area inside trace loops, etc.
  • The orientation of components should consider not only simplicity of assembly but also the need to test the circuitry afterward. This is the time to remember the need for test points!
  • The place for switches, press buttons, plug-in connectors, LEDs and other user-interface components is outside the enclosure. Anything requiring subsequent access should be on the front panel of the case.
  • Components that require assembling with the right polarity should all have the same orientation.
  • Manual routing is preferable to using the autorouter. The latter has its uses nevertheless for discovering bottlenecks and other critical points.
  • When routing, never even think about giving up! Many PCBs appear “unroutable” at the outset, yet after a while it turns out you have plenty of space to spare.
  • If you’re not satisfied with your efforts, it’s better to go back a step or two rather than just muddle onwards.
  • Complete the routing for each of the functional groups of the circuit first. Link the groups together only after you have finished this stage.
  • Short traces are better than long ones. High impedance connections are more sensitive to interference and for this reason require to be kept as short as possible.
  • Where traces form a loop, their surface area should be kept to an absolute minimum.
  • Decoupling capacitors must be located as close as possible to the switching element that needs to be decoupled.
  • Traces carrying signals should be routed early on (first the short ones, then the long ones). Except, that is, when the power supply traces are particularly critical.
  • Bus lines should be routed alongside one another.
  • Separate analog circuitry from digital whenever possible.PCB2
  • On multilayer boards arrange traces carrying signals so that one of the layers hosts the vertical traces and another one accommodates the horizontal ones.
  • If possible, reserve one layer or side exclusively for a continuous ground plane. Only in exceptional situations, e.g. with high speed op-amps, is this undesirable.
  • Keep traces carrying heavy currents well away from sensitive pickups, sensors and so on.
  • Beginners should take special care with mains and high voltages!
  • Ground and earth traces require exactly the same consideration as the power supply traces. Electromagnetic interference can be minimized by keeping the power and ground traces parallel (or better still arranged over each other on either side of a double-sided board).
  • Bends should be no more than 45°. Sharp angles between the traces and the pads are also to be avoided.
  • Observe PCB manufacturers’ requirements without exception in order to avoid unpleasant surprises later.
  • If you are using software for checking conformity to specifications, carry out these checks regularly at each design phase.
  • A border of 0.12″ (approximately 3 mm) around the edge of the PCB should be kept entirely clear of components.
  • If components are to be inserted by machine you must provide at least three location marks.
  • Don’t forget the holes for fixing screws or pillars!
  • Don’t skimp on text markings on the PCB: indicate polarity, voltages, on-board functions, part designation, design date, version number…
  • Check not just twice but three times that all components will actually fit the PCB!
  • Leave time at the end of the process for tidying up and optimizing.

Good luck!

Testing Power Supplies (EE Tip #112)

How can you determine the stability of your lab or bench-top supply? You can get a good impression of the stability of a power supply under various conditions by loading the output dynamically. This can be implemented using just a handful of components.

Power supply testing

Power supply testing

Apart from obvious factors such as output voltage and current, noise, hum and output resistance, it is also important that a power supply has a good regulation under varying load conditions. A standard test for this uses a resistor array across the output that can be switched between two values. Manufacturers typically use resistor values that correspond to 10% and 90% of the rated power output of the supply.

The switching frequency between the values is normally several tens of hertz (e.g. 40 Hz). The behavior of the output can then be inspected with an oscilloscope, from which you can deduce how stable the power supply is. At the rising edge of the square wave you will usually find an overshoot, which is caused by the way the regulator functions, the inductance of the internal and external wiring and any output filter.

This dynamic behavior is normally tested at a single frequency, but the designers in the Elektor Lab have tested numerous lab supplies over the years and it seemed interesting to check what happens at higher switching frequencies. The only items required for this are an ordinary signal generator with a square wave output and the circuit shown in Figure 1.Fig1-pwrsupply

You can then take measurements up to several megahertz, which should give you a really good insight for which applications the power supply is suitable. More often than not you will come across a resonance frequency at which the supply no longer remains stable and it’s interesting to note at which frequency that occurs.

The circuit really is very simple. The power MOSFET used in the circuit is a type that is rated at 80 V/75 A and has an on-resistance of only 10 mΩ (VGS = 10 V).

The output of the supply is continuously loaded by R2, which has a value such that 1/10th of the maximum output current flows through it (R2 = Vmax/0.1/max). The value of R1 is chosen such that 8/10th of the maximum current flows through it (R1 = Vmax/0.8/max). Together this makes 0.9/max when the MOSFET conducts. You should round the calculated values to the nearest E12 value and make sure that the resistors are able to dissipate the heat generated (using forced cooling, if required).

At larger output currents the MOSFET should also be provided with a small heatsink. The gate of the FET is connected to ground via two 100-Ω resistors, providing a neat 50-Ω impedance to the output of the signal generator. The output voltage of the signal generator should be set to a level between 5 V and 10 V, and you’re ready to test. Start with a low switching frequency and slowly increase it, whilst keeping an eye on the square wave on the oscilloscope. And then keep increasing the frequency… Who knows what surprises you may come across? Bear in mind though that the editorial team can’t be held responsible for any damage that may occur to the tested power supply. Use this circuit at your own risk!

— Harry Baggen and Ton Giesberts (Elektor, February 210)

Electronics Grounding (EE Tip #107)

Whether you are professional electrical engineer or part-time DIYer, before you start your next project, read through this primer on grounding. This short survey covers one of the most fundamental topics in electronics: grounding.

Electronics Signal Ground or Circuit Common

Signal ground is the current return to the power supply. Current leaves the power supply, passes through the various electronic components, and then returns to the supply. The typical symbol for signal ground is shown in Figure 1.EE107-F1-2

 Chassis Ground or Earth Ground

Chassis ground is an electrical safety requirement to prevent an electrical or electronic device’s chassis from delivering an electrical shock. A long copper rod is driven into the ground outside of the building, and a wire connects the metal chassis to the rod which is at the approximate 0 V potential of the earth. The symbol for earth ground is shown in Figure 2.

Ground Details

Consider the following two details about ground. First, ground is not exactly 0 V. And second, two physically different ground points will not be at the same voltage potential.

Ground Loop

By definition, current will flow in an electrical conductor connected to a difference in voltage potential between two points. Because two physically different ground points are not at the same potential, current will flow through an electrical conductor connected between those two points. This is a ground loop.

Notice this current flowing between these two different ground points is not related to or correlated to any electronic data or message signal. This is noise or garbage that will interfere and distort any information contained in the electronic system.

Note: While “noise” can be added to systems on occasion, it is specifically controlled and the exact quantity is regulated.


Given: A ground loop producing 610 μV of ground noise. It’s a very small quantity. You have a 16-bit A/D converter with a 0- to 10-V input. The smallest voltage it can resolve is:

= 10 V/16 exp 2

= 10 V/65,536

= 152.5ìV

Note that the ground loop noise is four times greater than the actual data, so that A/D converter loses two bits of resolution, and it is now a 14-bit converter.

Connect with Single-Ended/Unbalanced Amps

In Figure 3 the two grounds exist at different potentials, so some current will flow between the grounds. EE107-F3

This ground current has nothing to do with any signals being amplified, and it is noise decreasing the accuracy of the system. Figure 4 is a complete schematic.EE107-F4

Connect with Transformers

When connecting with transformers, keep the following in mind:

  • There is no ground connection, so there can be no Ground Loop.
  • Common-mode rejection of RF interference.
  • Signals are AC coupled, so of limited use for circuits with DC data such as accelerator focus and bend magnets (see Figure 5).EE107-F5

Connect with Differential Amps

Refer to Figure 6 for connecting two systems with differential amplifiers.

  • There is no ground connection, so there can be no Ground Loop.
  • Common-mode rejection of RF interference (see Figure 7).
  • Signals are DC coupled, so this is the perfect solution for circuits with DC data.EE107-F6EE107-F7

—Dennis Hoffman

Note: This article first appeared in audioXpress  (June 2011). It is from a class that Dennis Hoffman teaches at the SLAC National Accelerator Laboratory (Menlo Park, CA). Like Circuit Cellar, audioXpress is Elektor International Media Publication.

Programmable Logic Video Lessons

Interested in learning more about programmable logic? You’re in luck. Colin O’Flynn’s first article in his “Programmable Logic in Practice” column appears in Circuit Cellar’s October 2013 issue. To accompany his work, Colin is producing informative videos for you to view after reading his articles.

In the first video, Colin covers the topic of adding the Xilinx ChipScope ILA/VIO core using automatic and manual insertion with ISE.


Since 2002, Circuit Cellar has published several of O’Flynn’s articles. O’Flynn  is an engineer and lecturer at Dalhousie University in Halifax, Nova Scotia. He earned a Master’s in applied science from Dalhousie and pursued further graduate studies in cryptographic systems. Over the years, he has developed a wide variety of skills ranging from electronic assembly (including SMDs) to FPGA design in Verilog and VHDL to high-speed PCB design.

Embedded Sensor Innovation at MIT

During his June 5 keynote address at they 2013 Sensors Expo in Chicago, Joseph Paradiso presented details about some of the innovative embedded sensor-related projects at the MIT Media Lab, where he is the  Director of the Responsive Environments Group. The projects he described ranged from innovative ubiquitous computing installations for monitoring building utilities to a small sensor network that transmits real-time data from a peat bog in rural Massachusetts. Below I detail a few of the projects Paradiso covered in his speech.


Managed by the Responsive Enviroments group, the DoppelLab is a virtual environment that uses Unity 3D to present real-time data from numerous sensors in MIT Media Lab complex.

The MIT Responsive Environments Group’s DoppleLab

Paradiso explained that the system gathers real-time information and presents it via an interactive browser. Users can monitor room temperature, humidity data, RFID badge movement, and even someone’s Tweets has he moves throughout the complex.

Living Observatory

Paradiso demoed the Living Observatory project, which comprises numerous sensor nodes installed in a peat bog near Plymouth, MA. In addition to transmitting audio from the bog, the installation also logs data such as temperature, humidity, light, barometric pressure, and radio signal strength. The data logs are posted on the project site, where you can also listen to the audio transmission.

The Living Observatory (Source: http://tidmarsh.media.mit.edu/)


The GesturesEverywhere project provides a real-time data stream about human activity levels within the MIT Media Lab. It provides the following data and more:

  • Activity Level: you can see the Media Labs activity level over a seven-day period.
  • Presence Data: you can see the location of ID tags as people move in the building

The following video is a tracking demo posted on the project site.

The aforementioned projects are just a few of the many cutting-edge developments at the MIT Media Lab. Paradiso said the projects show how far ubiquitous computing technology has come. And they provide a glimpse into the future. For instance, these technologies lend themselves to a variety of building-, environment-, and comfort-related applications.

“In the early days of ubiquitous computing, it was all healthcare,” Paradiso said. “The next frontier is obviously energy.”

Embedded Wireless Made Simple

Last week at the 2013 Sensors Expo in Chicago, Anaren had interesting wireless embedded control systems on display. The message was straightforward: add an Anaren Integrated Radio (AIR) module to an embedded system and you’re ready to go wireless.

Bob Frankel demos embedded mobile control

Bob Frankel of Emmoco provided a embedded mobile control demonstration. By adding an AIR module to a light control system, he was able to use a tablet as a user interface.

The Anaren 2530 module in a light control system (Source: Anaren)

In a separate demonstration, Anaren electrical engineer Mihir Dani showed me how to achieve effective light control with an Anaren 2530 module and TI technology. The module is embedded within the light and compact remote enables him to manipulate variables such as light color and saturation.

Visit Anaren’s website for more information.

Open-Source Hardware for the Efficient Economy

In the open-source hardware development and distribution model, designs are created collaboratively and published openly. This enables anyone to study, modify, improve, and produce the design—for one’s own use or for sale. Open-source hardware gives users full control over the products they use while unleashing innovation—compared to the limits of proprietary research and development.

This practice is transforming passive consumers of “black box” technologies into a new breed of user-producers. For consumers, open-source hardware translates into better products at a lower cost, while providing more relevant, directly applicable solutions compared to a one-size-fits-all approach. For producers, it means lower barriers to entry and a consequent democratization of production. The bottom line is a more efficient economy—one that bypasses the artificial scarcity created by exclusive rights—and instead focuses on better and faster development of appropriate technologies.

Open-source hardware is less than a decade old. It started as an informal practice in the early 2000s with fragmented cells of developers sharing instructions for producing physical objects in the spirit of open-source software. It has now become a movement with a recognized definition, specific licenses, an annual conference, and several organizations to support open practices. The expansion of open-source hardware is also visible in a proliferation of open-source plans for making just about anything, from 3-D printers, microcontrollers, and scientific equipment, to industrial machines, cars, tractors, and solar-power generators.

As the movement takes shape, the next major milestone is the development of standards for efficient development and quality documentation. The aim here is to deliver on the potential of open-source products to meet or exceed industry standards—at a much lower cost—while scaling the impact of collaborative development practices.

The Internet brought about the information revolution, but an accompanying revolution in open-source product development has yet to happen. The major blocks are the absence of uniform standards for design, documentation, and development process; accessible collaborative design platforms (CAD); and a unifying set of interface standards for module-based design—such that electronics, mechanical devices, controllers, power units, and many other types of modules could easily interface with one another.

Can unleashed collaboration catapult open-source hardware from its current multimillion dollar scale to the next trillion dollar economy?

One of the most promising scenarios for the future of open source hardware is a global supply chain made up of thousands of interlinked organizations in which collaboration and complementarity are the norm. In this scenario, producers at all levels—from hobbyists to commercial manufacturers—have access to transparent fabrication tools, and digital plans circulate freely, enabling them to build on each other quickly and efficiently.

The true game changers are the fabrication machines that transform designs into objects. While equipment such as laser cutters, CNC machine tools, and 3-D printers has been around for decades, the breakthrough comes from the drastically reduced cost and increased access to these tools. For example, online factories enable anyone to upload a design and receive the material object in the mail a few days later. A proliferation of open-source digital fabrication tools, hackerspaces, membership-based shops, fab labs, micro factories, and other collaborative production facilities are drastically increasing access and reducing the cost of production. It has become commonplace for a novice to gain ready access to state-of-art productive power.

On the design side, it’s now possible for 70 engineers to work in parallel with a collaborative CAD package to design the airplane wing for a Boeing 767 in 1 hour. This is a real-world proof of concept of taking development to warp speed—though achieved with proprietary tools and highly paid engineers. With a widely available, open-source collaborative CAD package and digital libraries of design for customization, it would be possible for even a novice to create advanced machines—and for a large group of novices to create advanced machines at warp speed. Complex devices, such as cars, can be modeled with an inviting set of Lego-like building blocks in a module-based CAD package. Thereafter, CNC equipment can be used to produce these designs from off-the-shelf parts and locally available materials. Efficient industrial production could soon be at anyone’s fingertips.

Sharing instructions for making things is not a novel idea. However, the formal establishment of an open-source approach to the development and production of critical technologies is a disruptive force. The potential lies in the emergence of many significant and scalable enterprises built on top of this model. If such entities collaborate openly, it becomes possible to unleash the efficiency of global development based on free information flows. This implies a shift from “business as usual” to an efficient economy in which environmental and social justice are part of the equation.


Catarina Mota is a New York City-based Portuguese maker and open-source advocate who cofounded the openMaterials (openMaterials.org) research project, which is focused on open-source and DIY experimentation with smart materials. She is both a PhD candidate at FCSHUNL and a visiting scholar at NYU, and she has taught workshops on topics such as hi-tech materials and simple circuitry. Catarina is a fellow of the National Science and Technology Foundation of Portugal, co-chair of the Open Hardware Summit, a TEDGlobal 2012 fellow, and member of NYC Resistor.

Marcin Jakubowski graduated from Princeton and earned a PhD Fusion Physics from the University of Wisconsin. In 2003 Marcin founded the Open Source Ecology (OpenSourceEcology.org) network of engineers, farmers, and supporters. The group is working on the Global Village Construction Set (GVCS), which is an open-source, DIY toolset of 50 different industrial machines intended for the construction of a modern civilization (http://vimeo.com/16106427).

This essay appears in Circuit Cellar 271, February 2013.

RL78 Challenge Winner’s Workspace in Lewisville, TX

Lewisville, TX-based electrical engineer Michael Hamilton has been a busy man. During the past 10 years, he created two companies: A&D Technologies, which supplies wireless temperature and humidity controllers, and Point & Track, which provides data-gathering apps and other business intelligence tools. And in his spare time, he designed a cloud electrofusion machine for welding 0.5″ to 2″ polyethylene fittings. It  won Second Prize in the 2012 Renesas RL78 Green Energy Challenge.

In an interview slated for publication in Circuit Cellar 273 (April 2013), Hamilton describes some of his projects, shares details about his first microcontroller design, and more.

Michael Hamilton in his workspace. Check out the CNC machine and 3-D printer.

During the interview process, he also provided a details about his workspace, in which he has a variety of interesting tools ranging from a CNC machine to a MakerBot 3-D printer. Hamilton said:

I have a three-axis CNC machine and MakerBot 3-D printer. I use the CNC machine to cut out enclosures and the 3-D printer to create bezels for LCDs and also to create 3-D prototypes. These machines are extremely useful if you need to make any precise cuts or if you want to create 3-D models of future products.

Hamilton also noted:

I recently purchased a Rigol Technologies DSA-815-TG spectrum analyzer. This device is a must-have, right behind the oscilloscope. It enables you to see all the noise/interference present in a PCB design and also test it for EMI issues.

Michael Hamilton’s test bench and DSA815

He has a completely separate area for PCB work.

A separate space for PCB projects

Overall, this is an excellent setup. Hamilton clearly has a nice collection must-have EE tools and test equipment, as well as a handy CNC machine and decent desktop storage system. The separate PCB bench is a great feature that helps keep the space orderly and clean.

As for the 3-D printer, well, it’s awesome.

Engineer Survey: Skills, Topics, & Preferences

The electrical engineers, academics, and students who read Circuit Cellar hail from a wide range locations across the globe, such as the US, Brazil, India, The Netherlands, Germany, the UK, and Japan. Despite having different languages and cultures, the readers share a common dedication to and passion for electrical engineering.

This is a portion of our survey results. Link to the full set of results below.

In late 2012, we surveyed a random sample of more than 1,000 members of our community on their technical interests and preferences. We asked questions such as the following: How often do you solder? How many milliamps have you felt? Do you know more than three programming languages? Do you use FPGAs? Which companies make the best embedded products? And more!

Check out the results.

Read CC25 for more survey information, as well as interesting essays on the past, present, and future electrical engineering by engineers, business leaders, professors, and students.

CC271: Got Range?

As with wireless connectivity, when it comes to your engineering skills, range matters. The more you know about a variety of applicable topics, the more you’ll profit in your professional and personal engineering-related endeavors. Thus, it makes sense to educate yourself on a continual basis on the widest range of topics you can. It can be a daunting task. But no worries. We’re here to help. In this issue, we feature articles on topics as seemingly diverse as wireless technology to embedded programming to open-source development. Let’s take a closer look.

Consider starting with Catarina Mota and Marcin Jakubowski’s Tech the Future essay, “Open-Source Hardware for the Efficient Economy” (p. 80). They are thoughtful visionaries at the forefront of a global open-source hardware project. You’ll find their work exciting and inspirational.

Stuart Ball’s Dip Meter

On page 20, Stuart Ball describes the process of designing a digital dip meter. It’s a go-to tool for checking a device’s resonant frequency, or you can use it as a signal source to tune receivers. Ball used a microcontroller to digitize the dip meter’s display.

Interested in 3-D technology? William Meyers and Guo Jie Chin’s 3-D Paint project (p. 26) is a complete hardware and software package that uses free space as a canvas and enables you to draw in 3-D by measuring ultrasonic delays. They used a PC and MATLAB to capture movements and return them in real time.

This month we’re running the third article in Richard Lord’s series, “Digital Camera Controller” (p. 32). He covers the process of building a generic front-panel controller for the Photo-Pal flash-trigger camera controller project.

Richard Lord’s front panel CPU

Turn to page 37 for the fifth article in Bob Japenga’s series on concurrency in embedded systems. He covers the portable operating system interface (POSIX), mutex, semaphores, and more.

Check out the interview on page 41 for insight into the interests and work of electrical engineer and graduate student Colin O’Flynn. He describes some of his previous work, as well as his Binary Explorer Board, which he designed in 2012.

Colin O’Flynn’s Binary Explorer Board

In Circuit Cellar 270, George Novacek tackled the topic of failure mode and criticality analysis (FMECA). This month he focuses on fault-tree analysis (p. 46).

Arduino is clearly one of the hottest design platforms around. But how can you use it in a professional-level design? Check out Ed Nisley’s “Arduino Survival Guide” (p. 49).

Standing waves are notoriously difficult to understand. Fortunately, Robert Lacoste prepared an article on the topic that covers an experimental platform and measurements (p. 54).

This month’s article from the archives relates directly to the issue’s wireless technology theme. On page 60 is Roy Franz’s 2003 article about his WiFi SniFi design, which can locate wireless networks and then display “captured” packet information.

If you like this issue’s cover, you’ll have to check out Jeff Bachiochi’s article on QR coding (p. 68). He provides an excellent analysis of the technology from a pro engineer’s point of view.

Circuit Cellar 271 is now available.

Retro Electronics (“Retronics”): Analog, Test, & Micrcontroller Tech

Pop quiz: What was the first microcontroller to leave the Earth? Find out the answer in Jan Buiting’s new “Retronics” webinar. Check out the video below.

The Tektronix 546B

If you read Circuit Cellar and Elektor magazines, you likely have as much passion for old-school electronics as you do for he new, cutting-edge technology you find at events such as the Embedded Systems Conference. Elektor editor Jan Buiting is well-known for his love of both new and old technology, and in his Retronics webinar series he presents some of his favorite old-school technologies.

In the video below, Jan explains how and where he found some of his retronics equipment. He also details how he fixed some of the systems and what he does with them. Examples include:

  • A Heathkit TC-2P Tube Checker that Jan found at lawn sale
  • Old audio equipment
  • A satellite TV receiver
  • An “Elektorscope” from 1977
  • 1980s-era test equipment
  • And more!

CircuitCellar.com is an Elektor International Media publication.

Design a Low-Power System in 2013

A few months ago, we listed the top design projects from the Renesas RL78 Green Energy Challenge. Today, we’re excited to announce that Circuit Cellar‘s upcoming 25th anniversary issue will include a mini-challenge featuring the RL78. In the issue, you’ll learn about a new opportunity to register for an RL78/G14 demonstration kit that you can use to build a low-power design.

Renesas RL78

The RL78/G14 demonstration kit (RDK) is a handy evaluation tool for the RL78/G14 microcontrollers. Several powerful compilers and sample projects will be offered either free-of-charge (e.g., the GNU compiler) or with a code-size-limited compiler evaluation license (e.g., IAR Systems).  Also featured will be user-friendly GUIs, including the Eclipse-based e2studio.


  • 32-MHz RL78/G14 MCU board with integrated debugger and huge peripheral, including Wi-Fi, E Ink display, matrix LCD, audio ports, IR ports, motor control port, FET and isolated triac interfaces
  •  256-KB On-chip flash
  • USB Debugger cable
  • Four factory demos showcasing local and cloud connectivity through Wi-Fi

The CC25 anniversary issue is now available.