Estimated reading time: 8 minutes

Tim’s Takeaways: Clearing Up the Buzz

My first “real” job in the world of electronics was working at a Radio Shack store back in the late ‘70s. It was a step up from flipping burgers, but it didn’t last long. However, there was one notable aspect of that job; I was there during the time that Radio Shack introduced its first personal computer—the TRS-80. Although it is practically unimaginable now, in those days, there wasn’t much in the way of personal computing available for the general consumer. “Pong” and a few of its related home video games that connected to a television set had been out for a handful of years, but that was nothing compared to the millions of gaming options available today. And as far as personal computers go, in the late ‘70s, there were only a few options to pick from, including Apple, Commodore, and Tandy, or more commonly known as Radio Shack. After its introduction, the TRS-80 enjoyed a short period of time where it was the bestselling computer on the market with the largest selection of software.

I would like to say that I leveraged my short time at Radio Shack to the fullest by immersing myself in the world of computers and electronics. It would be great to include on my resumé how my experience with the TRS-80 gave me the computing and, ultimately, the PCB design foundation that I would base my career on, but it would all be a lie. The truth is that I was a kid who had just graduated from high school who didn’t have a clue to what the future held and was more interested in the “toy” qualities of the computer than in its educational possibilities. Because of that, I regret to admit that I spent all of my time on the TRS-80 playing games. Hey, if you find a subject like that tough to read, just imagine how hard it was for me to write. As they say, the truth hurts.

However, there was something very interesting about playing games on that computer. Unlike today’s systems, the first TRS-80s were so simple that they didn’t come with a built-in speaker; therefore, the games didn’t have any sound effects. To remedy this, I would grab a standard, portable AM radio off the shelf and set it up next to the computer while playing a game. The TRS-80 had a big problem, though—it radiated a lot of electromagnetic interference (EMI). The effect was so pronounced that it would produce a buzzing over the radio’s speaker that would vary in intensity and volume, depending on how active the computer was. For a game, this worked out better than you might think, and it is perhaps the only time in my life that I can think of where I used an EMI problem to my advantage. According to Wikipedia, the TRS-80 was actually discontinued primarily due to stricter FCC regulations on radio-frequency interference to other devices. As it turns out, I wasn’t the only one using a radio to produce sound effects out of that computer.

I have no idea what the circuit board or boards for the TRS-80 looked like, or with what level of technology they were designed, but from the amount of EMI that was created, there is probably a lot that they didn’t have. I would guess that the boards probably had as few layers as possible to reduce their production expenses. This would be at the cost of adequate ground planes for clean signal return paths and shielding. I would also assume that the routing on those boards may have been optimized for production instead of signal integrity, or perhaps there wasn’t any optimization at all, and the traces looped all over. Those would be my first guesses, but there are many other design details to consider, as well. These would range from the type of components that were on the board, how they were used, and how the casing was constructed. Wouldn’t it be fun to open up one of those old computers now just to see what made it tick, or rather, buzz?

PCB layout has changed a lot over the years. Back in those days, the signal speeds weren’t anywhere close to what we are dealing with today, and most of us had no idea how many design errors and EMI nightmares we were creating by today’s standards. Like the boards in the TRS-80, many of the PCBs I designed in those days would probably spray interference around like a yard sprinkler on a summer day if they were to be evaluated by today’s standards. Things are different now, and most designs that I am familiar with go through strict design control for EMI by the design team and the manufacturer. In addition, there is a lot of help available for designers to better understand EMI problems and how to avoid them in their designs. Some of this help includes the following:

Tools
The PCB design tools available to the user today are packed with features and functionality, and more is being added every day. In addition, circuit simulators and signal analysis tools are now more powerful, as well as being more affordable than ever. All of this has resulted in these analysis tools increasingly being integrated into the PCB design tools so that everyone has easy access to them.

Information
When I first started designing, any additional information that you wanted on a design subject would only be available in print, and I just didn’t get to the library that much. Today, you can easily search for information online and find scores of publications written on any given topic. You can also find various user groups online that are often eager to help and share their knowledge.

Education
The different venues for increasing your knowledge of design subjects continue to increase regularly. From the traditional education provided by schools and universities, to online courses, you can add to your education as needed. Additionally, there are scores of seminars and workshops available, and design trade shows will also offer many different classes hosted by industry professionals.

Networking
From co-workers and peers to online industry professionals, there’s a lot more professional and social networking available today that you can go to for help and advice. Designers aren’t nearly as isolated as they once were.

The industry is poised now better than it ever has been before to develop and create the next generation designs needed for our advancing technologies. Yet we still tend to bump into problems that stem from interference. As we’ve seen, there are plenty of different ways to deal with EMI problems in our designs, but what about other sources of interference? I’m sorry to say that for all of our efforts to reduce EMI in our designs, we aren’t always that great about dealing with workplace interference (WPI). Isn’t it ironic that for all the effort we can put into a PCB design to ensure its electromagnetic compatibility, the design could still be undermined by WPI? 

Communication, or lack thereof, seems to be one of the greatest causes of WPI in design teams. Some members of the team may not get informed in a timely manner when their input is needed or required. In other cases, team members are unsure of who to report to, or who gets the handoff of the next phase of the project. And no matter how much this topic gets covered in different seminars, workshops, and trade show classes, there is still a communication gap between some design teams and their manufacturers. In engineering teams, time is wasted, and mistakes are made because clear lines of communication have not been defined. If you want to avoid this kind of WPI in your workplace, here are a couple of ideas that may help you to clear up the interference:

• Have a defined workflow process in place: Your team members won’t know who does what, what the previous step was, where to go next, or how to escalate a problem without a plan that they can refer to.
• Identify a chain of command: Someone has to be the boss to make the decisions and field the important problems. If that person is you, then roll up your sleeves and get to work. Whether it’s on the court, at a school, or in the workplace, every team needs a leader.
• Design reviews: To ensure that the project is ready for each succeeding phase of the design, put into place regular design reviews. These reviews should be part of your workflow process, and key members of the design team should be involved.
• Keep the team engaged: Growth is an important part of success, but it can also isolate team members if you aren’t careful. Make sure to keep everyone engaged so that they understand their importance to the overall goal. In other words, don’t shy away from the occasional taco Tuesdays and casual Fridays. These are all good ideas to keep your team’s morale at a high level.

Whether it’s on a PCB or in the office, interference is never a good thing. Our engineering teams don’t need the annoying disruption that lack of communication brings to work, and I no longer have an AM radio on my desk to broadcast EMI-generated pseudo game sounds through. The more that we can clean up the buzz, the better off we’ll be. 
 
Until next time, my friends, keep on designing.
 
This column originally appeared in the February 2020 issue of Design007 Magazine.