About Circuit Cellar Staff

Circuit Cellar's editorial team comprises professional engineers, technical editors, and digital media specialists. You can reach the Editorial Department at editorial@circuitcellar.com, @circuitcellar, and facebook.com/circuitcellar

Solar-Power the Circuit Cellar (Free Download)

In the spirit of DIY engineering and solar power innovation, we’re re-releasing Circuit Cellar founder Steve Ciaria’s three-part series, “Solar-Powering the Circuit Cellar.”

An excerpt from the first article in the series appears below. And for a limited time, you can download the entire series for free. Enjoy!

The photos show the roof-mounted solar panels that produce approximately 40% of the total PV power. I know it sounds like a joke that the first PV system consideration is walking around the house and looking for the sun, but you can’t generate much energy if your panels are always shaded. When you live in the middle of the woods, finding the sun is often easier said than done.

Approximately 4,200 W of PV power is generated from 20 roof-mounted SunPower SPR-210 solar panels. The other 6,560 W comes from pole-mounted arrays behind this area.

Approximately 4,200 W of PV power is generated from 20 roof-mounted SunPower SPR-210 solar panels. The other 6,560 W comes from pole-mounted arrays behind this area.

Array orientation determines how much energy you can produce. Solar panels are typically aimed due south at a specific tilt angle that optimizes the incidence angle of the sunlight striking the panel. Maximum energy is produced when this tilt angle is equal to the latitude of the location (reduced by a location correction factor). Typically, the optimal tilt angle during the summer is the latitude minus 15°, and the optimal angle for the winter is the latitude plus 15°. Hartford, CT, is located at 42° latitude and the optimum tilt angle (minus an 8° correction factor) ranges from 19° in the summer (34° – 15°) to 49° in the winter (34° + 15°). The Connecticut rebate program suggests that if a fixed tilt is used, it be set at 35°. Of course, these are computer-generated optimizations that don’t necessarily accommodate real-world conditions. While it requires some nontrivial computer calculations to show authenticity, it is my understanding that as long as the non-optimal differences in azimuth and tilt are less than 20°, the loss in maximum power production is typically only about 5%. It is exactly for that reason that the most cost-effective PV installation is typically a fixed-pitch roof-mounted array.

Team installing solar panels on Steve Ciarcia's roof

Team installing solar panels on Steve Ciarcia’s roof

My system includes both variable and fixed-pitch arrays. The roof-mounted panels are located on the solarium roof and oriented at a fixed pitch of 17.5° facing SSW (see Photo 1). According to Sunlight Solar Energy’s calculations, efficiency is still about 92% of the desired maximum because the 17.5° roof angle actually allows higher efficiency during longer summer hours even though it isn’t the optimum tilt for winter.

Pole-mounted arrays are more efficient than a fixed-pitch roof array by design. My configuration is single-axis adjustable. The pole-mounted arrays are oriented due south and enable seasonal adjustment in the tilt angle to optimize the incidence angle of the sun. For everyone ready to e-mail me asking why I didn’t put in a tracking solar array since this is a pole mount, let me just say that you can also send me financial contributions for doing it via the magazine.—Steve Ciarcia, “Solar-Powering the Circuit Cellar (Part 1: Preparing the Site),” Circuit Cellar 209, 2007.

Check out some of Circuit Cellar’s other solar power-related articles and projects:

The Future of 3-D Printed Electronics

Three-dimensional printing technology is one of our industry’s most exciting innovations. And the promising field of 3-D printed electronics is poised to revolutionize the way engineers design and manufacture electrical systems for years to come. In the following essay, Dr. Martin Hedges of Neotech AMT presents his thoughts on the future of 3-D printed electronics.

Three-dimensional (3-D) printing for prototyping has been around for nearly three decades since the introduction of the first SL systems. The last few years have seen this technology receiving considerable attention to the point of hype in the mainstream media. However, there is a new emerging 3-D printing market that is increasing in importance: 3-D printed electronics (3-D PE). Whilst traditional 3-D printing builds structural parts layer by layer, 3-D PE prints liquid inks that have electronic functionality on to existing 3-D components. 3-D PE is achieved by combining advanced printing technologies, such as Aerosol Jet, with specially designed five-axis systems and advanced software controls that allow complex print motion to be achieved. The integrated print systems allow the full range of electronic functionality to be applied: conductors, semiconductors, resistors, dielectrics, optical, and encapsulation materials.

These can be printed on to virtually any surface material of almost any shape. Once deposited the inks are post processed: sintered, dried, or cured to achieve their final properties. Multiple materials can be printed to build up functionality, or surface mount devices (SMD) can be added to make the final electro-mechanically integrated system (see Photo 1).

Photo 1: 3-D PE demonstrator—Tank-filling sensor produced in the FKIA project funded by the Bavarian Research Foundation (Courtesy of Neotech AMT GmbH)

Photo 1: 3-D PE demonstrator—Tank-filling sensor produced in the FKIA project funded by the Bavarian Research Foundation (Courtesy of Neotech AMT GmbH)

In this example, two capacitive sensor structures have been printed on the ends of an injection-molded PA6 tank. The sensors are connected by a printed circuit (conductive Ag) and SMD components are added to complete the device. When water is pumped into the tank, the sensors register the water level as it rises, lighting the LEDs to indicate the fill level. When the tank compartment is full, the circuit senses the water fill level and reverses the pump direction.

3-D PE has the potential to provide enormous technical and economic benefits in comparison to conventional electronics based on 2-D printed circuit boards. It allows the combination of electronic, optic, and mechanical functions on shaped circuit carriers. Therefore, it enables entirely new product functions and supports the miniaturization and weight-saving potential of electronic products. By eliminating mechanical components, process chains can be shortened and reliability is increased. As a digitally driven, additive manufacturing process materials are only applied where needed, improving the ecological balance of electronics production. With no fundamental limitation on substrate material, the user is able to select low-cost, easy-to-recycle and more environmentally friendly materials. The novel design and functional possibilities offered by 3-D PE and the potential for rationalization of production steps indicate a potential quantum leap in electronics production.

Advances in this field have been rapid since the first developments that focused on 3-D chip packaging. In this field, printing is conducted over small changes in z-height to connect SMDs. Photo 2 shows an example where wire bonds are replaced by printing interconnects, from the PCB, up the side of a chip, and over onto the top contact pads.

Photo 2: 3-D chip packaging (Courtesy of Fraunhofer IKTS)

Photo 2: 3-D chip packaging (Courtesy of Fraunhofer IKTS)

Such applications only require  relatively simple print motion. The current “state of the art” is to use five axes of coordinated  motion  to  print high complex shapes. This capability enables the production of truly 3-D PE systems, such as a 3-D antenna for mobile devices (see Photo 3).

Photo 3: 3-D printed antenna (Courtesy of Lite-On Mobile)

Photo 3: 3-D printed antenna (Courtesy of Lite-On Mobile)

This application is well advanced and moving towards high-volume mass production driven by the benefits of a flexible manufacturing, novel design capabilities, and cost reduction compared to the current methods based on wet chemical plating processes. 3-D PE is also being scaled to print on large components beyond the size range possible with current manufacturing methods. For example, in the automotive field, 3-D prints of heater patterns are being developed for molded PC windscreens of up to 2 m × 1 m in size.

Currently, 3-D PE applications are mainly limited to circuits, antennas, strain gauges, or sensors using conductive metal as the print media with additional electronic functionality being added as SMDs. However, the technology also has the potential to leverage new material and process developments from the printed and organic electronics world. In this field, many different material systems are currently being applied on planar surfaces to create multi-material and multi-layer devices. Functionality such as resistors, capacitors, sensors, and even transistors are being incorporated into fully printed 2-D electronic systems. As these print materials and processes mature, they can be adapted to 3-D applications. It is expected that the coming years will see a rapid increase in the range of fully printed 3-D electronic devices of novel functionality.


Dr. Martin Hedges (mhedges@neotech-amt.com) is the Managing Director of Neotech AMT GmbH based in Nuremberg, Germany. His research includes aspects of additive manufacturing, materials and processes. His company projects focus on the development of integrated manufacturing systems for 3-D printed electronics.

Circuit Cellar 290 (September 2014) is now available.


Advanced Data-Logging Application

Measurement Computing Corp. (MCC) recently announced the release of DAQami, an advanced data-logging application that enables you to acquire, view, and log data from MCC USB DAQ devices.

DAQami currently supports over 40 MCC hardware devices

DAQami currently supports over 40 MCC hardware devices

In less than 5 minutes after installing DAQami and plugging in a DAQ device, you can create an automatic configuration and acquire live data, MCC noted in a release.

Data can be acquired in volts and degrees, as well as custom units with linear scaling. Channels can be viewed on any combination of scalar, strip, and block displays. Once data is acquired and logged, you can use DAQami to review the saved data file.

The DAQami user interface is flexible and provides the ability to customize display size and location, zoom factor, and channel/trace colors. You can configure MCC DAQ hardware within the application, selecting sam­pling rate, start and stop triggers, and sample count.

DAQami currently supports over 40 MCC hardware devices including the $99 100-ksps USB-201 DAQ device.

DAQami costs $49 when purchased with MCC DAQ hardware.

Source: Measurement Computing Corp.

Bluetooth Haptic Kit

Texas Instruments recently introduced an innovative wireless haptic development kit. The DRV2605EVM-BT haptic Bluetooth kit comprises a 32-mm square PCB containing a DRV2605 haptic driver chip that controls an eccentric rotating mass motor (ERM) and a linear resonant actuator (LRA) to produce vibrations. The DRV2605 has an integrated library with more than 100 effects licensed from Immersion Corp.

Texas Instruments DRV2605EVM-BT haptic Bluetooth kit

Texas Instruments DRV2605EVM-BT haptic Bluetooth kit

You can use a circle of LEDs to display visual alerts. The board might be useful to speed up development times when designing and testing haptic effects in applications such as: watches, fitness trackers, wearables, portable medical equipment, touch screens, displays, and other devices requiring tactile feedback.

A SimpleLink Bluetooth low-energy CC2541 wireless microcontroller communicates with a free iOS app running on an iPhone or iPad. The app allows you to play predefined library waveforms, create new waveform sequences, and assign waveform sequences to in-app notifications. The app can also be used to quickly configure the DRV2605’s internal register settings: select between an ERM or LRA actuator, set the rated and overdrive voltages, configure and run autocalibration, send direct I2C commands, as well as set up the board to respond to a GPIO trigger.

The DRV2605EVM-BT haptic Bluetooth kit costs $99.

Source: Texas Instruments

Book: Advanced Control Robotics

When it comes to robotics, the future is now! With the ever-increasing demand for robotics applications—from home control systems to animatronic toys to unmanned planet rovers—it’s an exciting time to be a roboticist. Whether you’re a weekend DIYer, a computer science student, or a professional engineer, you’ll find this book to be a valuable reference tool.

Advanced Control Robotics, by Hanno Sander

It doesn’t matter if you’re building a line-following robot toy or tasked with designing a mobile system for an extraterrestrial exploratory mission: the more you know about advanced robotics technologies, the better you’ll fare at your workbench. Hanno Sander’s Advanced Control Robotics (Elektor/Circuit Cellar, 2014) is intended to help roboticists of various skill levels take their designs to the next level with microcontrollers and the know-how to implement them effectively.

Advanced Control Robotics simplifies the theory and best practices of advanced robot technologies. You’re taught basic embedded design theory and presented handy code samples, essential schematics, and valuable design tips (from construction to debugging).

Sponsored by Circuit Cellar — Read the Table of Contents for Advanced Control Robotics. Ready to start learning? Purchase a copy of Advanced Control Robotics today!

You will learn about:

  • Control Robotics: robot actions, servos, and stepper motors
  • Embedded Technology: microcontrollers and peripherals
  • Programming Languages: machine level (Assembly), low level (C/BASIC/Spin), and human (12Blocks)
  • Control Structures: functions, state machines, multiprocessors, and events
  • Visual Debugging: LED/speaker/gauges, PC-based development environments, and test instruments
  • Output: sounds and synthesized speech
  • Sensors: compass, encoder, tilt, proximity, artificial markers, and audio
  • Control Loop Algorithms: digital control, PID, and fuzzy logic
  • Communication Technologies: infrared, sound, and XML-RPC over HTTP
  • Projects: line following with vision and pattern tracking
Hanno Sander at Work

Hanno Sander at Work

About the author: Hanno Sander earned a degree in Computer Science from Stanford University, where he built one of the first hybrid cars, collaborated on a microsatellite, and studied artificial intelligence. He later founded a startup to develop customized information services and then transitioned to product marketing in Silicon Valley with Oracle, Yahoo, and Verity. Today, Hanno’s company, HannoWare, seeks to make sophisticated technology—robots, programming languages, debugging tools, and oscilloscopes—more accessible. Hanno lives in Christchurch, New Zealand, where he enjoys his growing family and focuses on his passion of improving education with technology.