Electrical Engineering Innovation & Outreach

Bill Porter is a Panama City Beach, FL-based electronics engineer working for the US Navy. When he isn’t working on unmanned systems for the Navy, he spends his time running an engineering-focused educational outreach program and working on his own projects. In this interview, Bill talks about his first designs, technical interests, and current projects.

CIRCUIT CELLAR: You’re an electronics engineer for the United States Navy. Can you describe any of the projects you’re involved with?

BILL: I work with unmanned systems, or robots that are teleoperated and/or autonomous. This includes systems that swim under water, on the surface, or across the land. The Navy is working hard to develop robots to do the jobs that are dirty, dangerous, or dull and help keep the sailor out of harm’s way. One such system is called MUSCL, or Modular Systems Craft Littoral. MUSCL is a small, man-portable surface vehicle that is used by Riverine Patrol for remote surveillance and reconnaissance. I was the lead electrical engineer for the project.

Besides robots, I am also working on a few education outreach programs that work towards getting more students interested in STEM careers.

CIRCUIT CELLAR: Tell us about The Science Brothers nonprofit outreach program. How did the program start?

BILL: The Science Brothers is my main educational outreach program run out of my Navy base. For two Fridays every month, a few of my coworkers and I will visit a local elementary school to put on a show. The script of the show centers on the dynamics of two brothers, who specialize in different fields and argue over whose science is “cooler.” The result is a fun and wacky trip exploring different premises in science, such as light, sound, and energy, with examples and demonstrations from the realms of chemistry, physics, and electricity.

Science Brothers show

Science Brothers show

The program restarted when a few coworkers and I sat down and decided to bring back an old program that had existed on the base in the ‘90s called “Dr. Science.” The goal of the program was to bring science-based experiments to the schools using equipment they otherwise were not able to afford. By wowing the students with the spectacular-looking demos, we get them excited about science and yearning to learn more.

CIRCUIT CELLAR: Your website (BillPorter.info) includes projects involving 3-D printing, motor controllers, and LEDs. What types of projects do you prefer working on and why?

BILL: I am a hardware guy. I love to fire up my favorite PCB CAD software just to get an idea out of my head and on the screen. I do not breadboard very often, as I would rather take my chances trying some new idea on a board first. Either it works, or I have an excuse to design another PCB. Thankfully, group-order PCB services have enabled my addiction tinkering at a very low cost. I wish I was stronger at mechanical CAD design to really get the full potential out of my 3-D printer, but I have done well enough without it. It really does come in handy at times, whether it is a quick project enclosure, a mount, or a part for our garden.

Bill is self-proclaimed "hardware guy"

Bill is self-proclaimed “hardware guy”

CIRCUIT CELLAR: Do you have a favorite project?

BILL: Yes! My wedding of course! I married the girl of my dreams who is just as much as a geek as I am, and as a result, we had an extremely geeky wedding over a year in the making involving many projects throughout. So much so that our theme was “Circuit and Swirls” and we carried the motif throughout.

Wedding gadgets

Wedding gadgets

We designed and made our own wedding invitations involving LEDs, a microprocessor, and a clever Easter egg. Furthermore, we 3-D-printed our centerpieces, built up our own “e-textile” wedding attire with LEDs and EL wire, and we even had a “soldering ceremony” during the event. It made our parents nervous, but in the end, everyone had a good time. Did I mention I asked her to marry me on a PCB she designed for a project?

EE-themed wedding invitations

EE-themed wedding invitations

CIRCUIT CELLAR: Are you currently working on or planning any projects? Can you tell us about them?

BILL: I have one main project that is taking up all my time at work and at home. A coworker and I are the technical directors for the first-ever Maritime RobotX Challenge. The challenge, sponsored by Association for Unmanned Vehicle Systems International (AUVSI) Foundation and by the Office for Naval Research (ONR), will take place this October in Singapore. It will include 15 teams of college students from five participating nations and put them to the test by challenging them to design a robot that will complete five tasks autonomously. As one of the technical directors, I have been helping design and build the interactive course elements that the teams’ robots will be facing. Find out more at Robotx.org.

CIRCUIT CELLAR: What new technologies excite you and why?

BILL: I have always been infatuated by LEDs and ways to conserve energy, so I am most excited to see how efficient LEDs are starting to take over as the new source of light in the household.

The complete interview appears in Circuit Cellar 291 (October 2014).

Electronics “Mancave”: Small-Footprint Workspace

When it comes to a workspace, more doesn’t necessarily mean better. We encourage engineers and DIYers to focus their time and money on engineering, not on acquiring new and used equipment they’ll never use.

Belgium-based Jan Cumps has a very basic yet effective workspace. It is a true workspace. That means he actually has room to work there. It isn’t a cluttered room for storing junk.

Source: Jan Cumps

Source: Jan Cumps

Cumps noted:

I’m a clean-desker. Have to share it with studying kids. All gear has to have small footprint, or must be stow-away-able. That’s why you see a 4-in-1 multimeter, power supply, frequency counter and function generator, and a 2-in-1 hot air plus solder station. Components, meters, cables and what have you are stowed a way in boxes.

His equipment:

  • Philips MP 3305 oscilloscope
  • Metex MS-9150 4-in-1
  • Micronta (Tandy) and Metrix multimeters
  • Old-school soldering gear 
Share your space! Circuit Cellar is interested in finding as many workspaces as possible and sharing them with the world. Click here to submit photos and information about your workspace. Write “workspace” in the subject line of the email, and include info such as where you’re located (city, country), the projects you build in your space, your tech interests, your occupation, and more. If you have an interesting space, we might feature it on CircuitCellar.com!

 

Freescale High-Sensitivity Accelerometer Family

Freescale recently introduced a new range of three-axis accelerometers offering high sensitivity at low power consumption. According to Freescale, the FXLN83xxQ family is capable of detecting acceleration information often missed by less accurate sensors commonly used in consumer products such as smartphones and exercise activity monitors. In conjunction with appropriate software algorithms, its improved sensitivity allows the new sensor to be used for equipment fault prognostication (for predictive maintenance), condition monitoring, and medical tamper detection applications.

Source: Freescale

Source: Freescale

The 3 mm × 3 mm chip has a bandwidth of 2.7 kHz and uses analog output signals for direct connection to a microcontroller’s ADC input. Each chip has two levels of sensitivity that can be changed on the fly. The complete family covers acceleration ranges of ±2, ±4, ±8, and ±16 g, with gains of, 229.0, 114.5, 57.25, and 28.62 mV/g, respectively. Zero g is indicated by an output level of 0.75 V.

The FXLN83xxQ family:

  • FXLN83x1Q ±2 or ±8 g range
  • FXLN83x2Q ±4 or ±16 g
  • FXLN836xQ 1.1 kHz x- and y-axis bandwidth (Z = 600 Hz)
  • FXLN837xQ 2.7 kHz x- and y-axis bandwidth (Z = 600 Hz)

The sensors operate from 1.71 to 3.6 V (at 180 µA typically, 30 nA shutdown). The company has also made available the DEMOFXLN83xxQ evaluation break-out board with a ready-mounted sensor to simplify device integration into a test and development environment.

A Wire Is an Inductor (EE Tip #126)

I’m confident you know that you should keep wires and PCB tracks as short as possible. But I’m also sure that you will underestimate this problem fairly frequently.

Remember that 1 cm of a 0.25-mm-wide PCB track is roughly equivalent to an inductance of 10 nH. If this 10 nH is paired with, say, a 10-pF capacitor, that gives a resonant frequency as low as 500 MHz, which is easily below the third or fifth harmonics of the clock frequencies commonly seen on modern high-speed digital boards. Similarly, a 1-cm-long track will jeopardize the performances of any RF system such as a 2.4-GHz transceiver. There is only one solution: keep tracks and wires as short as possible. If you can’t, then use impedance-matched tracks.

Remember this rule especially for the ground connections: any grounded pad of any part working in high frequencies should be directly connected by avia to the underlying ground plane. And this via must be as close as possible to the pad, not some millimeters away.

Just yesterday I did a design review of a customer’s RF PCB. A small 0402 inductance was grounded through a via that was 3 mm away. It was a bad idea because the inductance was as low as 1 nH. Those 3 mm changed its value completely.—Robert Lacoste, “Mixed-Signal Designs,” CC25:25th Anniversary Issue, 2013. 

Prototyping for Engineers (EE Tip #111)

Prototyping is an essential part of engineering. Whether you’re working on a complicated embedded system or a simple blinking LED project, building a prototype can save you a lot of time, money, and hassle in the long run. You can choose one of three basic styles of prototyping: solderless breadboard, perfboard, and manufactured PCB. Your project goals, your schedule, and your circuit’s complexity are variables that will influence your choice. (I am not including styles like flying leads and wire-wrapping.)PrototypeTable

Table 1 details the pros and cons associated with each of the three prototyping options. Imagine a nifty circuit caught your eye and you want to explore it. If it’s a simple circuit, you can use the solderless breadboard (“white blob”) approach. White blobs come in a variety of sizes and patterns. By “pattern” I mean the number of the solderless connectors and their layout. Each connector is a group (usually five) of tie points placed on 0.1″ centers. Photo 1 shows how these small strips are typically arranged beneath the surface.Prototype p1-4

Following the schematic, you use the tie points to connect up to five components’ leads together. Each tie point is a tiny metal pincer that grips (almost) any lead plugged into it. You can use small wires to connect multiple tie points together or to connect larger external parts (see Photo 2).

If you want something a bit more permanent, you might choose to use the perfboard (“Swiss cheese”) approach. Like the solderless breadboards, perfboards are available in many sizes and patterns; however, I prefer the one-hole/ pad variety (see Photo 3). You can often find perfboards from enclosure manufacturers that are sized to fit the enclosures (see Photo 4).

There is nothing worse than wiring a prototype PCB and finding there isn’t enough room for all your parts. So, it pays to draw a part layout before you get started just to make sure everything fits. While I’m at it, I’ll add my 2¢ about schematic and layout programs.

The staff at Circuit Cellar uses CadSoft EAGLE design software for drawing schematics. (A free version is available for limited size boards.) I use the software for creating PCB layouts, drawing schematics, and popping parts onto PCB layouts using the proper board dimensions. Then I can use the drawing for a prototype using perfboard.

The final option is to have real prototypes manufactured. This is where the CAD software becomes a necessity. If you’ve already done a layout for your hand-wired prototype, most of the work is already done (sans routing). Some engineers will hand-wire a project first to test its performance. Others will go straight to manufactured prototypes. Many prototype PCB manufacturers offer a bare-bones special—without any solder masking or silkscreen—that can save you a few dollars. However, prices have become pretty competitive. (You can get a few copies of your design manufactured for around $100.)

There are two alternatives to having a PCB house manufacture your PCBs: do-it-yourself (DIY) and routing. If you choose DIY approach, you’ll have to work with ferric chloride (or another acid) to remove unwanted copper (see Photo 5). You’ll be able to produce some PCBs quickly, but it will likely be messy (and dangerous).Prototype p5-6

Routing involves using an x-y-z table to route between copper traces to isolate them from one another (see Photo 6). You’ll need access to an x-y-z table, which can be expensive.—CC25, Jeff Bachiochi, “Electrical Engineering: Tricks and Tools for Project Success,” 2013.

This piece originally appeared in CC25 2013