Application Engineering: An Interview with Carmen Parisi

Carmen Parisi is an applications engineer who co-hosts an engineering podcast in his spare time. In this interview, he describes his work, shares some engineering tips, and  tells us about a fun prank he played on an unsuspecting designer.

CIRCUIT CELLAR: Where are you located?

CARMEN: Currently, I’m living and working in Raleigh-Durham, NC, around the Research Triangle Park area between the two cities with my wife and new dog Sadie. Kelly and I moved down about three years ago from Buffalo, NY, and really like it here. There’s a lot of tech companies and engineers around, tons of stuff to do, and great food and beer scenes. Plus, as a hearty Northerner, I get to laugh at the “cold” winters we experience. Come summer, though, I melt into a puddle on the pavement. Snow all the way for me, but Kelly disagrees.

Carmen Parisi

Carmen Parisi

CIRCUIT CELLAR: When did you decide to pursue electrical engineering and why?

CARMEN: Ever since I was a kid I had a fascination with tools and how things worked. I would always have a toy sword and various tools stuffed into my belt and would volunteer to help my dad around the house building a deck around the pool or fixing the fence.

Once I got into high school, I took a few basic engineering courses during which time I got bit by the engineering bug. The course that really “doomed” me to a life of electronics was a Robotics course taught by my favorite teacher C, as we called him. He put me through my paces learning how to solder, reading schematics, programming in BASIC, and robbing Fort Knox using a LEGO Mindstorms robot. C’s class solidified my choice to go to college for engineering, and shortly thereafter, I picked electrical over mechanical for my major.

CIRCUIT CELLAR: When was the first time you used a microcontroller in a project?

CARMEN: If we’re counting LEGO Mindstorms, then the Robotics class in tenth grade with C where we had to build a robot to lift a golden brick and run away with it (thus “robbing Fort Knox”). I met all the individual milestones with my group for the project, but we couldn’t get the whole thing working smoothly from beginning to end. I guess that was my first time learning how to successfully fail too which has turned out to be a very useful skill.

My first real microcontroller experience was the summer after sophomore year when I took a college course at a local community college offering a few classes to high school students interested in engineering. During that course I learned more basic circuit theory, got introduced briefly to SMT soldering, and built some robots using the Parallax BOE Bot. Looking back, I’d say this was the time my analog career kicked off as I slowly started to realize that I was more interested in the circuits themselves than the overall robot.

CIRCUIT CELLAR: Tell us about your university-level schooling.

CARMEN: I still consider myself a student in that I’m always looking to learn new things and grow as an engineer, but my formal schooling is over for the foreseeable future. In 2011, I completed a combined BS/MS degree in Electrical Engineering at the Rochester Institute of Technology in Rochester, NY. I initially started off interested in robotics but after working with a great analog designer on my first co-op at GE, I switched into the analog circuit and semiconductor track and never looked back.

CIRCUIT CELLAR: Can you tell us about your work in graduate school?

CARMEN: Sure thing. My graduate work was primarily with the Communications professor who needed a proof of concept built to test out a theory that looked plausible on paper. Prior to my joining the Comms Lab, my advisor and two past grad students had worked out a method of securing wireless channels using the randomness of the channel itself. There was an initial front end of sorts to test the idea out but I don’t think it was ever tested.

I looked over the circuit design, decided to scrap it and start fresh, and immediately realized I had a big job ahead of me. Cue the analog professor becoming my co-advisor. Mixing circuits, active filters, phase detectors, ADCs, and communication theory swam through my head as I slowly cajoled the circuit to life. Two PCB revisions later the circuit worked in that it took the RF input signal and spat out some bits at the other end, but after my advisor applied his algorithm to the data, we weren’t able to generate symmetric keys on different boards. Whether this was from an error in theory or with my board I never found out, as I ended the project there to focus on my full-time job leaving with a grad paper instead of a full thesis.

I still have all my old lab notebooks, schematics, and board layouts on my bookshelf at home. I think the files are sitting on a hard drive somewhere too. Looking at them now, I can spot a lot of little errors I’d like to fix due to my inexperience at the time and some maybe a few not so little errors too.

CIRCUIT CELLAR: What did you do after school?

CARMEN: After I left RIT, I moved down here to Raleigh-Durham to start my career as an Applications Engineer working on switching regulators with Intersil. Back in 2009 I had done a summer stint as an FAE at a small field office in Long Island with the company which got me interested in working in the semiconductor industry.

Life on the road as an FAE didn’t appeal to me after spending my college years constantly moving around for co-ops, so my former boss set me up with an interview here at the RTP design center. On the way down for the interview, I got stuck in Dulles for the night thanks to some bad weather in Rochester causing me to miss my connection. I wound up getting a bare 3 hours of sleep that night on an empty terminal bench. The next morning, groggy and sleep deprived, I suited up in the family restroom and flew out for six wonderful hours of technical interviews. I was absolutely wiped out by the end of the day but managed to survive the ordeal. The rest is history.

CIRCUIT CELLAR: Tell us about the work you are doing as an applications engineer for Intersil.

CARMEN: Well, for starters, being an apps engineer is exactly the rock n’ roll lifestyle I’m sure all your readers expect it to be. I roll into the office every morning and have the roadies warm up my iron for me!

In reality though, I work on buck regulators for computing applications like notebooks, tablets, ultrabooks, with maybe a bit of desktop work from time to time. Most of the parts I work on are for the primary core voltage on Intel processors. Sometimes, should the part integrate multiple regulators, I’ll work on a graphics rail or one of the other many voltage rails present on a motherboard. For each new processor tock (tick? I always confuse the two), Intel releases a laundry list of specs that have to be met in order to provide power to their CPUs and my parts are designed to those specs.

When I work apps on a brand spanking new chip, I’ll first work with the design engineers to run some feasibility studies and help define any new features for the IC. These tests range from tuning a similar part to the new Intel specs to see if the control scheme hits any corners or has stability issues to beating up some power FETs to determine if they can handle the new current requirements we have to meet. Once the chip tapes out, I’ll start work on preliminary documentation—a rough datasheet draft or early reference design based on feasibility testing and simulations—for the field to use when working with customers. During this time, I also design the evaluation board I’ll use to validate the part and send to customers for sampling.

The real meat and potatoes of my job is silicon validation. I’ve got an exhaustive spreadsheet of bench tests to do that functionally verify the IC over a wide range of corners. The first few weeks after silicon comes back I’m working full throttle, round the clock if need be, to make sure there are no show stopping bugs we need to address. I never see my office during validation. Instead I’m spending all my time in the lab hunched over the eval board or squinting at my scope.

Things calm down slightly after the initial validation, but the work is still nowhere near done. Now I’m working with design and test engineers to debug any issues that crept up during validation and implement fixes. Ideally, a board-level change is found because PCB or apps level schematic changes are much easier and cheaper than silicon spins. In conjunction with this work, I’ll also refine my reference designs and documentation as well as work with the field on initial customer designs by answering questions and checking over layouts and schematics to make sure everything’s optimal for their builds.

Up until the part releases, I’ll continue cycling through validation, debug, and customer support as needed, squeezing in documentation when I get a chance too. At any given time, I’m also supporting old parts still in production or, if I’m in a lull with my work, getting pulled onto other chips to help out other apps engineers in a jam.

The last part I released, and my first as the lead apps guy, was the ISL95813, a single phase regulator for Haswell and Broadwell systems. My next part is scheduled for release next year which I can’t talk too much about, but it’s really cool.

CIRCUIT CELLAR: During your time at Intersil, you must have learned some important lessons about professional engineering. Can you share one or two things you took from the experience?

CARMEN: Most importantly, good communication skills are key. A large chunk of my job is talking to other engineers and customers across the country and overseas. Their whole interaction with me is through the emails and reports I send out and I want to make sure they’re top notch. You don’t need to be a poet laureate by any means, but if you come across like a rock head, it will be much harder to get taken seriously and problems will drag out longer than necessary. Proofread your work; make sure you’re getting your point across clearly; and tailor your email, report, PowerPoint, whatever, to your audience’s level of technical expertise. Study up on how to make a slideshow that won’t bore your audience or read a technical writing guide. It can’t hurt.

Secondly, document, document, document—even if it’s only for your own reference. And keep it somewhat organized so you can find what you need again without too much hassle. Yes, it can help CYA, but also I’ve saved myself a ton of time not redoing the same derivations or looking back at a difficult test setup I had documented in my notebooks. It’s especially nice being able to pull up old data from past parts to see why the heck we did what we did years later.

CIRCUIT CELLAR: Tell us about your most recent electrical engineering project. What did you build and why?

CARMEN: Well, I can’t talk too much about work since all my projects at the moment are either customer related or under development, but suffice it to say I’m working on a lot of low power, multi-role chips.

Outside of work though for nearly two years now I’ve been co-hosting a podcast which keeps me plenty busy. The show’s called The Engineering Commons and it gets released every other week by myself and three other engineers scattered across the US. It was originally started by Chris Gammell and Jeff Shelton, but when Chris left the show for other projects back in 2013, I threw my hat into the ring when Jeff put the word out he was looking for new co-hosts. We discuss the engineering discipline as a whole rather than focus on any one field and some of our favorite topics include education, the value of co-ops, life in the workplace, and the stories of other engineers we bring on to interview.

The semiconductor field is pretty niche, and so through the show, I get exposed to all sorts of new ideas and philosophies, whether it’s from researching a topic when coming up with show notes or hearing the stories of engineers and professors from across the globe. Some of my favorite episodes are the ones while interviewing a guest I barely have to say anything and not just because I hate hearing my voice when I re-listen to an episode! Hearing someone get really into a story and talk about their passion I can’t help but get drawn in and become excited myself. All us engineers are alike; no matter the field once you get us going about that tricky bug we finally tracked down, the ridiculous meeting that happened the other day, or those ah-ha moments when a solution just clicks in your head we just can’t help but gush and it makes for great content. I’ve put out nearly 50 episodes with Jeff, Adam, and Brian, and I can’t wait to do the next 50!

CIRCUIT CELLAR: Tell our readers about the prank circuit gag you pulled on the designer you worked with. And can you share an image of the prank circuit?

CARMEN: A good way through the 813 development I found some problems that ended up being non-issues because I misinterpreted a spec, had a test setup issue, or made a silly component choice in my design. The designer started ribbing me a bit by immediately calling everything a board issue from that point on. This kind of back and forth goes on all the time between apps and design and it’s always good natured in tone. I didn’t take it personally and took strides to be more thorough before ringing alarm bells going forward but I couldn’t let him get way Scot-free.

Prank circuit

Prank circuit

With my boss’ permission I waited until a slow day came along and rigged up a little circuit to the bottom of the eval board that would overdrive the compensation node of our regulator, propagate through the control loop, and cause seemingly random spikes in the output voltage. I took some waveforms and sent them off to the designer explaining how I found an operational corner that affected regulation we needed to address. Since he was a thorough designer and liked to regularly pop into the apps lab I actually spent my morning running the tests he asked me to just to keep up the illusion something was wrong if he showed up.

I kept him digging through the schematics trying to find his mistake until mid-afternoon before I brought him in the lab and slowly flipped the board over while telling him I found the error was caused by a parasitic circuit. At this point a couple other engineers who were in on the gag had found reasons to be in the lab for the reveal and we all had a good laugh. The designer took it pretty well, and I even bought him a beer for being a good sport.

You can read the entire interview in Circuit Cellar 295 (February 2015).

Mandalas Blend Technology and Spirituality

Multimedia artist Leonardo Ulian’s work includes his stunning “Technological Mandala” series, in which he precisely arranges tiny electrical and computer components to create colorful and symmetrical mandalas. In Hindu and Buddhist cultures, a mandala is a geometric and spiritual artwork representing the universe and is used in meditation. In this interview, Leonardo discusses his background, artwork, and inspiration for blending technological and ephemeral themes.—Mary Wilson, Managing Editor


MARY: Where were you born and how long have you lived in London?

LEONARDO: I come from a little village called Ruda, situated in the northeast region of Italy, Friuli-Venezia Giulia. I have lived in London since 2004.

Technological Mandala 17: Electronic components, copper wire, paper, 72 cm x 72 cm, 2013 (closeup),

Technological Mandala 17: Electronic components, copper wire, paper, 72 cm x 72 cm, 2013 (closeup). (Photo courtesy of Leonardo Ulian)

MARY: I understand you started out pursuing a degree in micro-electronics, then trained as a graphic designer before earning a fine arts degree. Can you tell me about your education and what made you turn your training toward the arts?

LEONARDO: My first attempt to do art was more related to the activity of just making things. Since I was very young, I always liked to play with hammers, nails, pieces of wood, and other bits and pieces in order to make my own little toys. But more than anything else, I liked to open old radios to see what was hiding inside.

In the 1980s, I attended an electronics school, also because I was fascinated by the new technology revolution of that period. I do remember myself stuck in front of the television watching an American TV series about robots, computers, and all that sort of stuff. While I was studying electronics I attended an art course and I specialized in airbrush hyper-realistic painting techniques. I then studied graphic design and I worked as a graphic designer and photo-retoucher for several years until I moved to London where I obtained my BA degree in fine art.

Technological Mandala 17: Electronic components, copper wire, paper, 72 cm x 72 cm, 2013.

Technological Mandala 17: Electronic components, copper wire, paper, 72 cm x 72 cm, 2013.

MARY: How did you come up with the idea for the “Technological Mandala” series? What was your inspiration and what are you trying to convey with these pieces that solder together electrical components, circuitry, and microchips?

LEONARDO: I liked the idea of combining different worlds such as spirituality and mandalas with technology and underlining the fact that electronic technology devices have become fundamental for our daily lives, almost something to worship.

I am also fascinated by the pure exercise of geometry used for the construction of the traditional mandalas—an ordered representation that is used to explain something that probably has nothing to do with geometry, which is the meaning of everything we perceive around us as living beings. I guess my artistic and spiritual research have led me to discover the world of mandalas.

I am not a spiritual person, or at least not in the traditional manner. And I am not particularly polarized with a specific belief. But I do like the idea of a world made with infinite connections among persons, objects, or places, like the connections I make in my technological mandalas. I also like to believe that what happens in one of the parts of the connection can affect the others as well.

Electronic components have always fascinated me; there was something in them that has attracted my fantasy since I was very young. I always asked myself how these little things were able to do what they do within electronic devices. After my studies in fine art, I started to think about my old passions and interests in a different way. This is why now, in my eyes, the electronic components have lost their real functionality in order to become ephemeral objects able to trigger the eyes and minds of the viewers, but in a different manner.

Technological Mandala 38: Electronic components, white Perspex, triple mounting board, 60 x 60 cm, 2013 (close up).

Technological Mandala 38: Electronic components, white Perspex, triple mounting board, 60 cm x 60 cm, 2013 (close-up). (Photo courtesy of Leonardo Ulian)

MARY:  Can you describe how you created the pieces? The materials and techniques you used?

LEONARDO: I make the basic geometry design in a computer. I print the resulting image onto paper, and then I bring in countless electronic components—some recycled but most bought from online websites—to fill in the shape I have created. I spend hours online researching nice and colorful electronic components. The difficulty is that nowadays technology is moving toward miniaturizing the electronic components, and quite often they do not have any color code.

MARY: You started the series two years ago. Is it now complete?

LEONARDO: The series isn’t yet completed, it’s a work in progress and I do not know when it will be finished. I guess the series is evolving as the technology—especially the electronic one—is changing rapidly.

Technological Mandala 02 (the beginning). Electronic components, microchip, wood frame, 120 x 20 cm, 2012.

Technological Mandala 02 (the beginning). Electronic components, microchip, wood frame, 120 cm x 20 cm, 2012. (Photo courtesy of Leonardo Ulian)

MARY: Do you have other artwork, such as “Technological Mandala,” that presents technology in an unconventional and thought-provoking way? Can you tell me more about that work?

LEONARDO: One of my early pieces is called “Now and Forever.” It’s an old petrol lantern modified in order to have, instead of the real flame, a mini-LCD screen with a video of it. The virtual flame within the mini screen is powered by a DVD player instead of the petrol, and it could run forever—or at least until there is no longer electricity available.

"Now and Forever" (Photo courtesy of Leonardo Ulian)

“Now and Forever” (Photo courtesy of Leonardo Ulian)

MARY: What technologies most interest you? Do any of them intrigue you as inspiration for future projects? If so, how might you use them?

LEONARDO: I do not have a particular interest in a specific piece of technology; I like to pick up things that stimulate my imagination. But, among other things, I am fascinated by magnetic fields and how the spectator could interact with them in order to generate art.

The piece “Close to the Essence” explores my interest in magnetic fields. It is a system of elements, like a hi-fi system, that becomes a totem able to interact with the spectator. The whole structure becomes a giant theremin I made using three simple AM radios, and the sound generated by the sculpture varies according to the proximity of the viewers.

"Close to the Essence" (Photo courtesy of Leonardo Ulian)

“Close to the Essence” (Photo courtesy of Leonardo Ulian)

MARY: What project are you currently focusing on?

LEONARDO: At the moment I am focused on further developing the idea started with the “Technological Mandala” series.

MARY: Do you have a dream project, something you are resolved to do sometime during your artistic career?

LEONARDO: I do not have a specific dream project, although my sketchbooks are full of ideas. I try to work day by day in order to produce things I am happy with. I have to say that almost always I have doubts about the things I make, but this keeps me going forward to create the next piece.

Technological Mandala 05: Electronic components, microchip, wood frame, 60 x 57 cm, 2012. (Photo courtesy of Leonardo Ulian)

Technological Mandala 05: Electronic components, microchip, wood frame, 60 cm x 57 cm, 2012. (Photo courtesy of Leonardo Ulian)


“Dardoby” (Photo courtesy of Leonardo Ulian)

MARY: You are a self-described multimedia artist. Can you tell me about some of your other artistic pursuits, including The Apathy Band you co-founded?

LEONARDO: I do like to think that art can explore different fields, as the great master Leonardo da Vinci did in his practice. The Apathy Band is an open project created by the artists Bob and Roberta Smith and I am one of the co-founders. The instruments I play in the band are toys I have accurately modified, like old electronic keyboards or electronic gizmos and animated toys. Two examples are the Dardomin, a theremin I created using AM radios, and the Dardoby, a circuit-bent Furby toy puppet I use to generate unexpected sound. I have also collaborated with the artistic duo Marotta & Russo to create the soundtracks of their videos. (Refer to “Timeline” and “Netopia.”)

Leonardo Ulian has had numerous solo exhibitions in London and elsewhere. He is the recipient of the Owen Rowley Award, London (UK), and the Italian national prize Stamps of the XX Century. You can follow Leonardo on Twitter at @ulianleonardo.

Technological Mandala 29: Electronic components, copper wire, paper, 120 cm x 120 cm, 2013. (Photo courtesy of Leonoard Ulian)

Technological Mandala 29: Electronic components, copper wire, paper, 120 cm x 120 cm, 2013. (Photo courtesy of Leonardo Ulian)


Centrical Bonsai Tree: Electronic components, cement and steel base, 135 cm x 35 cm x 35 cm, 2013 (close-up).

Centrical Bonsai: Tree, electronic components, cement and steel base, 135 cm x 35 cm x 35 cm, 2013 (close-up). (Photo courtesy of Leonardo Ulian)

Centrical Bonsai Tree: Electronic components, cement and steel base, 135 cm x 35 cm x 35 cm, 2013 (close-up).

Centrical Bonsai: Tree, electronic components, cement and steel base, 135 cm x 35 cm x 35 cm, 2013. (Photo courtesy of Leonardo Ulian)


Q&A: Hacker, Roboticist, and Website Host

Dean “Dino” Segovis is a self-taught hardware hacker and maker from Pinehurst, NC. In 2011, he developed the Hack A Week website, where he challenges himself to create and post weekly DIY projects. Dino and I recently talked about some of his favorite projects and products. —Nan Price, Associate Editor


NAN: You have been posting a weekly project on your website, Hack A Week, for almost three years. Why did you decide to create the website?

Dean "Dino" Segovis at his workbench

Dean “Dino” Segovis at his workbench

DINO: One day on the Hack A Day website I saw a post that caught my attention. It was seeking a person to fill a potential position as a weekly project builder and video blogger. It was offering a salary of $35,000 a year, which was pretty slim considering you had to live in Santa Monica, CA. I thought, “I could do that, but not for $35,000 a year.”

That day I decided I was going to challenge myself to come up with a project and video each week and see if I could do it for at least one year. I came up with a simple domain name,, bought it, and put up a website within 24 h.

My first project was a 555 timer-based project that I posted on April 1, 2011, on my YouTube channel, “Hack A Week TV.” I made it through the first year and just kept going. I currently have more than 3.2 million video views and more than 19,000 subscribers from all over the world.

NAN: Hack A Week features quite a few robotics projects. How are the robots built? Do you have a favorite?

rumblebot head

Dino’s very first toy robot hack was the Rumble robot. The robot featured an Arduino that sent PWM to the on-board H-bridge in the toy to control the motors for tank steering. A single PING))) sensor helped with navigation.

Rumble robot

The Rumble robot

DINO: I usually use an Arduino as the robot’s controller and Roomba gear motors for locomotion. I have built a few others based on existing wheeled motorized toys and I’ve made a few with the Parallax Propeller chip.

My “go-to” sensor is usually the Parallax PING))) ultrasonic sensor. It’s easy to connect and work with and the code is straightforward. I also use bump sensors, which are just simple contact switches, because they mimic the way some insects navigate.

Nature is a great designer and much can be learned from observing it. I like to keep my engineering simple because it’s robust and easy to repair. The more you complicate a design, the more it can do. But it also becomes more likely that something will fail. Failure is not a bad thing if it leads to a better design that overcomes the failure. Good design is a balance of these things. This is why I leave my failures and mistakes in my videos to show how I arrive at the end result through some trial and error.

My favorite robot would be “Photon: The Video and Photo Robot” that I built for the 2013 North Carolina Maker Faire. It’s my masterpiece robot…so far.

NAN: Tell us a little more about Photon. Did you encounter any challenges while developing the robot?

Photon awaits with cameras rolling, ready to go forth and record images.

Photon awaits with cameras rolling, ready to go forth and record images.

DINO: The idea for Photon first came to me in February 2013. I had been playing with the Emic 2 text-to-speech module from Parallax and I thought it would be fun to use it to give a robot speech capability. From there the idea grew to include cameras that would record and stream to the Internet what the robot saw and then give the robot the ability to navigate through the crowd at Maker Faire.

I got a late start on the project and ended up burning the midnight oil to get it finished in time. One of the bigger challenges was in designing a motorized base that would reliably move Photon across a cement floor.

The problem was in dealing with elevation changes on the floor covering. What if Photon encountered a rug or an extension cord?

I wanted to drive it with two gear motors salvaged from a Roomba 4000 vacuum robot to enable tank-style steering. A large round base with a caster at the front and rear worked well, but it would only enable a small change in surface elevation. I ended up using that design and made sure that it stayed away from anything that might get it in trouble.

The next challenge was giving Photon some sensors so it could navigate and stay away from obstacles. I used one PING))) sensor mounted on its head and turned the entire torso into a four-zone bump sensor, as was a ring around the base. The ring pushed on a series of 42 momentary contact switches connected together in four zones. All these sensors were connected to an Arduino running some simple code that turned Photon away from obstacles it encountered. Power was supplied by a motorcycle battery mounted on the base inside the torso.

The head held two video cameras, two smartphones in camera mode, and one GoPro camera. One video camera and the GoPro were recording in HD; the other video camera was recording in time-lapse mode. The two smartphones streamed live video, one via 4G to a Ustream channel and the other via Wi-Fi. The Ustream worked great, but the Wi-Fi failed due to interference.

Photon’s voice came from the Emic 2 connected to another Arduino sending it lines of text to speak. The audio was amplified by a small 0.5-W LM386 amplifier driving a 4” speaker. An array of blue LEDs mounted on the head illuminated with the brightness modulated by the audio signal when Photon spoke. The speech was just a lot of lines of text running in a timed loop.

Photon’s brain includes two Arduinos and an LM386 0.5-W audio amplifier with a sound-to-voltage circuit added to drive the mouth LED array. Photon’s voice comes from a Parallax Emic 2 text-to-speech module.

Photon’s brain includes two Arduinos and an LM386 0.5-W audio amplifier with a sound-to-voltage circuit added to drive the mouth LED array. Photon’s voice comes from a Parallax Emic 2 text-to-speech module.

Connecting all of these things together was very challenging. Each component needed a regulated power supply, which I built using LM317T voltage regulators. The entire current draw with motors running was about 1.5 A. The battery lasted about 1.5 h before needing a recharge. I had an extra battery so I could just swap them out during the quick charge cycle and keep downtime to a minimum.

I finished the robot around 11:00 PM the night before the event. It was a hit! The videos Photon recorded are fascinating to watch. The look of wonder on people’s faces, the kids jumping up to see themselves in the monitors, the smiles, and the interaction are all very interesting.

NAN: Many of your Hack A Week projects include Parallax products. Why Parallax?

DINO: Parallax is a great electronics company that caters to the DIY hobbyist. It has a large knowledge base on its website as well as a great forum with lots of people willing to help and share their projects.

About a year ago Parallax approached me with an offer to supply me with a product in exchange for featuring it in my video projects on Hack A Week. Since I already used and liked the product, it was a perfect offer. I’ll be posting more Parallax-based projects throughout the year and showcasing a few of them on the ELEV-8 quadcopter as a test platform.

NAN: Let’s change topics. You built an Electronic Fuel Injector Tester, which is featured on Can you explain how the 555 timer chips are used in the tester?

DINO: 555 timers are great! They can be used in so many projects in so many ways. They’re easy to understand and use and require only a minimum of external components to operate and configure.

The 555 can run in two basic modes: monostable and astable.

Dino keeps this fuel injector tester in his tool box at work. He’s a European auto technician by day.

Dino keeps this fuel injector tester in his tool box at work. He’s a European auto technician by day.

An astable circuit produces a square wave. This is a digital waveform with sharp transitions between low (0 V) and high (+ V). The durations of the low and high states may be different. The circuit is called astable because it is not stable in any state: the output is continually changing between “low” and “high.”

A monostable circuit produces a single output pulse when triggered. It is called a monostable because it is stable in just one state: “output low.” The “output high” state is temporary.

The injector tester, which is a monostable circuit, is triggered by pressing the momentary contact switch. The single-output pulse turns on an astable circuit that outputs a square-wave pulse train that is routed to an N-channel MOSFET. The MOSFET turns on and off and outputs 12 V to the injector. A flyback diode protects the MOSFET from the electrical pulse that comes from the injector coil when the power is turned off and the field collapses. It’s a simple circuit that can drive any injector up to 5 A.

This is a homebrew PCB for Dino's fuel injector tester. Two 555s drive a MOSFET that switches the injector.

This is a homebrew PCB for Dino’s fuel injector tester. Two 555s drive a MOSFET that switches the injector.

NAN: You’ve been “DIYing” for quite some time. How and when did your interest begin?

DINO: It all started in 1973 when I was 13 years old. I used to watch a TV show on PBS called ZOOM, which was produced by WGBH in Boston. Each week they had a DIY project they called a “Zoom-Do,” and one week the project was a crystal radio. I ordered the Zoom-Do instruction card and set out to build one. I got everything put together but it didn’t work! I checked and rechecked everything, but it just wouldn’t work.

I later realized why. The instructions said to use a “cat’s whisker,” which I later found out was a thin piece of wire. I used a real cat’s whisker clipped from my cat! Anyway, that project sparked something inside me (pun intended). I was hooked! I started going house to house asking people if they had any broken or unwanted radios and or TVs I could have so I could learn about electronics and I got tons of free stuff to mess with.

My mom and dad were pretty cool about letting me experiment with it all. I was taking apart TV sets, radios, and tape recorders in my room and actually fixing a few of them. I was in love with electronics. I had an intuition for understanding it. I eventually found some ham radio guys who were great mentors and I learned a lot of good basic electronics from them.

NAN: Is there a particular electronics engineer, programmer, or designer who has inspired the work you do today?

DINO: Forrest Mims was a great inspiration in my early 20s. I got a big boost from his “Engineer’s Notebooks.” The simple way he explained things and his use of graph paper to draw circuit designs really made learning about electronics easy and fun. I still use graph paper to draw my schematics during the design phase and for planning when building a prototype on perf board. I’m not interested in any of the software schematic programs because most of my projects are simple and easy to draw. I like my pencil-and-paper approach.

NAN: What was the last electronics-design related product you purchased and what type of project did you use it with?

DINO: An Arduino Uno. I used two of these in the Photon robot.

NAN: What new technologies excite you and why?

DINO: Organic light-emitting diodes (OLEDs). They’ll totally change the way we manufacture and use digital displays.

I envision a day when you can go buy your big-screen TV that you’ll bring home in a cardboard tube, unroll it, and place it on the wall. The processor and power supply will reside on the floor, out of the way, and a single cable will go to the panel. The power consumption will be a fraction of today’s LCD or plasma displays and they’ll be featherweight by comparison. They’ll be used to display advertising on curved surfaces anywhere you like. Cell phone displays will be curved and flexible.

How about a panoramic set of virtual reality goggles or a curved display in a flight simulator? Once the technology gets out of the “early adopter” phase, prices will come down and you’ll own that huge TV for a fraction of what you pay now. One day we might even go to a movie and view it on a super-huge OLED panorama screen.

NAN: Final question. If you had a full year and a good budget to work on any design project you wanted, what would you build?

DINO: There’s a project I’ve wanted to build for some time now: A flight simulator based on the one used in Google Earth. I would use a PC to run the simulator and build a full-on seat-inside enclosure with all the controls you would have in a jet airplane. There are a lot of keyboard shortcuts for a Google flight simulator that could be triggered by switches connected to various controls (e.g., rudder pedals, flaps, landing gear, trim tabs, throttle, etc.). I would use the Arduino Leonardo as the controller for the peripheral switches because it can emulate a USB keyboard. Just program it, plug it into a USB port along with a joystick, build a multi-panel display (or use that OLED display I dream of), and go fly!

Google Earth’s flight simulator also lets you fly over the surface of Mars! Not only would this be fun to build and fly, it would also be a great educational tool. It’s definitely on the Hack A Week project list!

Editor’s Note: This article also appears in the Circuit Cellar’s upcoming March issue, which focuses on robotics. The March issue will soon be available for membership download or single-issue purchase.


Places for the IoT Inside Your Home

It’s estimated that by the year 2020, more than 30 billion devices worldwide will be wirelessly connected to the IoT. While the IoT has massive implications for government and industry, individual electronics DIYers have long recognized how projects that enable wireless communication between everyday devices can solve or avert big problems for homeowners.

February CoverOur February issue focusing on Wireless Communications features two such projects, including  Raul Alvarez Torrico’s Home Energy Gateway, which enables users to remotely monitor energy consumption and control household devices (e.g., lights and appliances).

A Digilent chipKIT Max32-based embedded gateway/web server communicates with a single smart power meter and several smart plugs in a home area wireless network. ”The user sees a web interface containing the controls to turn on/off the smart plugs and sees the monitored power consumption data that comes from the smart meter in real time,” Torrico says.

While energy use is one common priority for homeowners, another is protecting property from hidden dangers such as undetected water leaks. Devlin Gualtieri wanted a water alarm system that could integrate several wireless units signaling a single receiver. But he didn’t want to buy one designed to work with expensive home alarm systems charging monthly fees.

In this issue, Gualtieri writes about his wireless water alarm network, which has simple hardware including a Microchip Technology PIC12F675 microcontroller and water conductance sensors (i.e., interdigital electrodes) made out of copper wire wrapped around perforated board.

It’s an inexpensive and efficient approach that can be expanded. “Multiple interdigital sensors can be wired in parallel at a single alarm,” Gualtieri says. A single alarm unit can monitor multiple water sources (e.g., a hot water tank, a clothes washer, and a home heating system boiler).

Also in this issue, columnist George Novacek begins a series on wireless data links. His first article addresses the basic principles of radio communications that can be used in control systems.

Other issue highlights include advice on extending flash memory life; using C language in FPGA design; detecting capacitor dielectric absorption; a Georgia Tech researcher’s essay on the future of inkjet-printed circuitry; and an overview of the hackerspaces and enterprising designs represented at the World Maker Faire in New York.

Editor’s Note: Circuit Cellar‘s February issue will be available online in mid-to-late January for download by members or single-issue purchase by web shop visitors.

The Future of Inkjet-Printed Electronics

Silver nanoparticle ink is injected into an empty cartridge and used in conjunction with an off-the-shelf inkjet printer to enable ‘instant inkjet circuit’ prototyping. (Photo courtesy of Georgia Institute of Technology)

Silver nanoparticle ink is injected into an empty cartridge and used in conjunction with an off-the-shelf inkjet printer to enable ‘instant inkjet circuit’ prototyping. (Photo courtesy of Georgia Institute of Technology)

Over the past decade, major advances in additive printing technologies in the 2-D and 3-D electronics fabrication space have accelerated additive processing—printing in particular—into the mainstream for the fabrication of low-cost, conformal, and environmentally friendly electronic components and systems. Printed electronics technology is opening an entirely new world of simple and rapid fabrication to hobbyists, research labs, and even commercial electronics manufacturers.

Historically, PCBs and ICs have been fabricated using subtractive processing techniques such as photolithography and mechanical milling. These traditional techniques are costly and time-consuming. They produce large amounts of material and chemical waste and they are also difficult to perform on a small scale for rapid prototyping and experimentation.

This single-sided wiring pattern for an Arduino microcontroller was printed on a transparent sheet of coated PET film, (Photo courtesy of Georgia Technical Institute)

This single-sided wiring pattern for an Arduino microcontroller was printed on a transparent sheet of coated PET film, (Photo courtesy of Georgia Technical Institute)

To overcome the limitations of subtractive fabrication, over the past decade the ATHENA group at the Georgia Institute of Technology (Georgia Tech) has been developing an innovative inkjet-printing platform that can print complex, vertical ICs directly from a desktop inkjet printer.

To convert a standard desktop inkjet printer into an electronics fabrication platform, custom electronic inks developed by Georgia Tech replace the standard photo inks that are ejected out of the printer’s piezoelectric nozzles. Inks for depositing conductors, insulators/dielectrics, and sensors have all been developed. These inks can print not only single-layer flexible PCBs, but they can also print complex, vertically integrated electronic structures (e.g., multilayer wiring with interlayer vias, parallel-plate capacitors, batteries, and sensing topologies to sense gas, temperature, humidity, and touch).

To create highly efficient electronic inks, which are the key to the printing platform, Georgia Tech researchers exploit the nanoscale properties of electronic materials. Highly conductive metals (e.g., gold, silver, and copper) have very high melting temperatures of approximately 1,000°C when the materials are in their bulk or large-scale form. However, when these metals are decreased to nanometer-sized particles, their melting temperature dramatically decreases to below 100°C. These nanoscale particles can then be dispersed within a solvent (e.g., water or alcohol) and printed through an inkjet nozzle, which is large enough to pass the nanoparticles. After printing, the metal layer printed with nanoparticles is heated at a low temperature, which melts the particles back into a highly conductive metal to produce very low-resistance electrical structures.

Utilizing nanomaterials has enabled the creation of plastic, ceramic, piezoelectric, and carbon nanotube and graphene inks, which are the fundamental building blocks of a fully printed electronics platform. The inks are then tuned to have the correct viscosity and surface tension for a typical desktop inkjet printer.

By loading these nanomaterial-based conductive, dielectric, and sensing inks into the different-colored cartridges of a desktop inkjet printer, 3-D electronics topologies such as metal-insulator-metal (MIM) capacitors can then be created by printing the different inks on top of each other in a layer-by-layer deposition. Since printing is a non-contact additive deposition method, and the processing temperatures are below 100⁰C, these inks can be printed onto virtually any substrate, including standard photo paper, plastic, fabrics, and even silicon wafers to interface with standard ICs with printed feature sizes below 20 µm.

The Georgia Tech-developed printing platform is a major breakthrough. It makes the cost of additively fabricating circuits nearly the same as printing a photo on a home desktop inkjet printer—and with the same level of simplicity and accessibility.

These advancements in 2-D electronics printing combined with current research in low-cost 3-D printing are enabling commercial-grade fabrication of devices that typically required clean room environments and expensive manufacturing equipment. Such technology, when made accessible to the masses, has the potential to completely change the way we think about building, interacting with, and even purchasing electronics that can be digitally transmitted and printed.  While the printing technology is currently at a mature stage, we have only scratched the surface of potential applications that can benefit from printing low-cost, flexible electronic devices.