Categories
Analog Electronics Engineering Learning

Where Will I Use This Electrical Engineering Stuff?

I find myself sitting around these days trying to catch up on knowledge I feel like I missed in school. Worse, I feel like I learned it at one time but it all fell out the other side once I took the exam. Pretty standard really, when you don’t think you’re going to need to the knowledge some day. Haven’t you ever sat in class wondering if you’d really ever use the material you were expected to learn? How much did you pay attention?

I feel that a requisite of every college class should be at least an entire class devoted to how you can use the knowledge contained in the remainder of the course material. It should probably happen close to the beginning of the semester or quarter. I have always lobbied for this kind of explanation and have always tried to include it whenever I am teaching something. Better yet, if someone from the field come in and explain how they use the knowledge in their working lives it would really drive the point home. When you know that you will definitely use certain knowledge, you’re more likely to sit up and pay attention.

Some of the material that I have been relearning lately has been tangential to the actual material we covered in classes back in my school days. Some of this is because I needed to go back and re-learn the absolute basics, such as semiconductor physics. I didn’t quite need to learn why a PN junction behaves as it does, only how it behaves and how it relates to larger devices such as transistors (basically a couple PN junctions specialized for certain behavior and placed in a certain configuration). I also don’t need to know why certain materials carry magnetic fields, only how they do and how you can use them to build a transformer. Other than re-learning the absolute basics, it’s driven by things I encounter in my daily work where I feel I was lacking. Very general topics but things that have very specific application in my job. Transformers are an area where I felt it was necessary to get more info, so I used my favorite resource (OhioLink) to get some textbooks based on co-workers recommendations. Hey, you just end up reading the textbook in some classes anyway, right? So why not?

So I guess that’s all I have to say about this topic. If you don’t know something, go to the library and and figure it out (I love libraries). And if books don’t show you what you need, ask a friend. Most importantly, find out where you might use the material you’re learning the first time you see it. If you’re not being directly told why you will need a certain piece of information, do the legwork yourself and figure out why you should care (someone saying “because it’s in the course outline” isn’t good enough). The application of the knowledge is much more important over the long term.

Got something you can’t figure out? Ask me in the comments.

Categories
Analog Electronics Digital Electronics Life Politics

The Digital Switchover and Why It’s About People

The Digital Switchover.

Not me. I almost did that a while back, but no. Not me.

Television.

Normally I wouldn’t write about it. A digital television standard is long overdue and in the end this will be a good thing. When you compare Analog vs Digital, there are many more benefits on the digital side of things: lower power for transmission, better bandwidth of signal, more bandwidth usage over the spectrum. All of these are good things. I can even talk about how those digital signals still have lots of analog components as they’re transmitted over the airwaves: multipath, signal loss, power calculation, reception problems, etc.

But no. I’d rather point something else out:

Technology adoption is driven by human nature. It must be adopted before it can help people.

Sure, the digital signals will be great. High Definition pictures and you don’t have to give a dime to those lovely cable companies. Lower power generation required to transmit the signals will help save the environment by lowering the carbon footprint. But until the switch actually happens (today…maybe), no one gets the benefits. The switchover has been delayed to now from this past February. Lawmakers deemed the country unready to make the switchover at that time. I mean, if people can’t watch TV, how will the politicians get their message out to the masses?

No matter how many new devices are introduced into the marketplace and no matter how available they make DTV switcher boxes, people still will not change until pushed. They will not go out and get the digital box or call their local politician until one day they turn on their television and the signal is not there. That is what will drive the final changeover. I wouldn’t be surprised if we saw a little bit more leeway from politicians before stations are officially told to shut off the analog transmitters.

This problem isn’t exclusive to television. This has happened for the past 30 years in conservation and renewable energy.  Regardless of how many times climate change experts point out we’re killing the planet, nothing moves until there is a scare that oil is running out (it is) or natural gas won’t always be available (it won’t) or coal is filthy (it is) or the power just goes out. Then people change their tune; they change gears and start thinking about buying that solar array or that home wind turbine. They start recycling again because they think it will start to help (it will, but what about the past 10 years of bottles you put in the landfill?). But the thing is, you need to think about buying the solar cells now, when there isn’t a 6 month backlog of installation requests and prices are jacked up due to demand. And Solar might even already be an affordable option for you.

I’m sure people will say there’s an economic aspect of it for DTV and that the people that use analog signals the most can’t afford the converter boxes. Perhaps that has some truth to it. But the point remains that no matter the technology, until that last group resistant or indifferent to change decides to go out and do something about it, those people can’t be helped.

What about you? Have you made the switchover yet? If not, why? Leave a note in the comments.

Categories
Analog Electronics Music

Co-workers Bring New Projects

One of the best parts of working with others interested in electronics is having similar hobbies: namely, electronics and music.  And even though I have similar hobbies, I never really brought them up in conversation with co-workers (believe me, some of the stuff I have done pales in comparison to some of the people I work with). However, in the past few weeks it has really paid off talking about my non-work work, both for my personal hobbies and for things to write about that interest me.

Tektronics 425M Oscilloscope:

A few months back I had mentioned how I blew up my Wurlitzer 200 and needed to start troubleshooting it for possible problems. I also lamented the fact that I didn’t have a scope to look at waveforms when I finally got the DC characteristic where I want them. Fast forward to a few weeks ago and a friend and co-worker mentions that he had a scope that he had purchased on eBay but was DOA. Apparently it broke in the midst of shipping and he didn’t get charged by the seller. He also bought a working scope later and intended to fix this one, but never got to it. As such he was clearing out room and offered it to me, a truly generous offer.

The scope itself is a dual channel, 100 MHz scope. It is a military version of the scope so it possibly has better spec’d parts (but I haven’t looked into this  too much).The main problem is that the beam does not render any images onto the phosphorescent screen. Other than that, it is supposed to work fine. Time will tell on the other components.

The interesting  thing about the older analog scopes is that many of them can be repaired by non-professionals. More accurately, they can be repaired by individuals not employed by Tektronics because the schematics are available, the components are large enough to replace quasi-easily and there aren’t proprietary ASICs you have to order from the OEM. One notable fixer-upper of all old things Tektronics is Jim Williams, applications engineer for Linear Technologies and electonics writer (my favorite thing about him is that he lists his 84 Tek scopes at home when he writes his own bios at the end of books or articles). All of these things lead to some analog engineers being die-hard fans of analog scopes. They also like that analog scopes never introduce sampling errors or glitches. This is less and less of a problem with new digital scopes on the market and yet the analog vs digital battle rages on (at least in my mind).

Oscilloscope

Oscilloscope

Goals/Projects:

  1. Get the front panel working
  2. Use it to troubleshoot any remaining hum and sound issues on the Wurlitzer 200
  3. Use it to aid me in creating a simple waveform generator (perhaps a buffered output from a computer?)
  4. Use it to troubleshoot issues that arise with the organ and other projects surrounding it

Hammond M3 Organ:

Another co-worker and I were discussing music one day and I mentioned my work on the Wurlitzer. He happened to mention how his wife would be very pleased if he would sell their organ; I was similarly pleased. I’ve been a fan of Hammond Organ in Soul Jazz and Jazz music (thanks Evan and Trevor) a while longer than I’ve been collecting the instruments used by them (thanks Noah).

The organ came to me in good shape sound wise; a little bit of hum but all of the keys are in really good shape and the drawbars work great. No Leslie speaker for now but the person who sold it to me says he might be able to sell me his model 900 eventually. I will also try and get one on my own in the mean time to see if I can’t get a better model (Model 122 or 145). The cosmetic condition of the organ is poor but I don’t think it would have as much character if the thing was squeaky clean. I also plan to possibly chop the organ at some point (put it into a smaller, transportable case) so the cosmetics don’t really matter.

Hammond M3 Organ Side

Hammond M3 Organ Front

Goals/Projects:

  1. Get the organ oiled and hum-less
  2. Successfully replace and re-bias the tubes on the main amplifier
  3. Build an external amplifier and cabinet to increase the sound output
  4. Create sound effect pedals to modify the sound output of the organ to my liking
  5. Document the internals of the tonewheel mechanism
  6. Chop the organ into a transportable case (less than the original weight of 250 lbs)

So these are some of my projects for the summer and possibly extending beyond into the rest of the year. I really look forward to working on two pieces of spectacularly engineered equipment. While I won’t be redesigning the equipment or doing much beyond touching up some of the worn out components, I hope to learn from the internals of these pieces of equipment and use them in future projects.

Do you have any ideas to build off of what I have listed here? What kind of projects are you working on this summer? Let me know in the comments!

Categories
Analog Electronics Digital Electronics Engineering

The Future of Troubleshooting

If you are an engineer who regularly works with your hands, you likely troubleshoot on a daily basis. It’s just part of the job. Sure, you can say, “I never mess up!”, but hardly anyone will believe you. Because even when your best laid plans go perfectly, Murphy’s Law will soon kick in to balance things out. We learn to deal with these things and have developed tools and measurement equipment to help us diagnose and deal with these problems: Multimeters, Electrometers, SourceMeters, Oscilloscopes, Network Analyzers, Logic Analyzers, Spectrum Analyzers, Semiconductor Test equipment (ha, guess I know a little about that stuff)…the list goes on and on. But what has struck me lately has been that as parts on printed circuit boards get smaller and smaller, troubleshooting is getting…well….more troubling.

  1. Package Types — I don’t want to get into another discussion of analog vs digital, but I will say that digital parts on average have many more pins which complicates things. And as the parts get more and more complex, they require more and more pins. The industry solution was to move to a Ball Grid Array package, using tiny solder balls on the bottom of the chip that then line up with a grid of similar sized holes on the board. When you heat up the part the solderballs melt and hold the chip into place and connects all of the signals. The problem is the size of the solderballs and the connecting vias: they’re tiny. Like super tiny. Like don’t try probing the signals without a microscope and some very small probes. But wait, it’s not just the digital parts! The analog parts are getting increasingly small to accommodate any of those now-smaller-but-still-considerably-bigger-than analog parts. You thought probing a digital signal was tough before? Now try measuring something that has more than 2 possible values!
  2. Board Layers — As the parts continue on their shrink cycle, the designers using these parts also want to place them closer together (why else would they want them so small?).The circuit board designers route signals down through the different layers of insulating material so that mutiple planes can be used to route isolated signals to different points on the board. So to actually route any signals to the multitude of pins available, more and more board layers are required as the parts get smaller and closer together. Granted, parts are still mounted on either the top or bottom of the board. But if a single signal is routed from underneath a BGA package, down through the fourth layer of an 8 layer board board and then up to another BGA package, the signal will be impossible to see and measure without ripping the board apart.
  3. High Clocks — As systems are required to go faster and faster, so are their clocks. Consumers are used to seeing CPU speeds in the GHz range and others using RF devices are used to seeing even higher, into the tens of GHz. The problem arises when considering troubleshooting these high speed components. If you have a 10 GHz digital signal and you expect the waveforms to be in any way square (as opposed to sinusoidal) you need to have spectral data up to the 5th harmonic. In this case, it means you need to see 50 GHz. However, as explained with analog to digital converters in the previous post, you need to sample at twice the highest frequency you are interested in to be able to properly see all of the data. 100 GHz! I’m not saying it’s impossible, just that the equipment required to make such a measurement is very pricey (imagine how much more complicated that piece of equipment must be). High speed introduces myriad issues when attempting to troubleshoot non-working products.
  4. Massive amounts of data — When working with high speed analog and digital systems there is a good amount of data available. The intelligent system designer will be storing data at some point in the system either for debugging and troubleshooting or for the actual product (as in an embedded system). When dealing with MBs and even GBs of data streaming out of sensors and into memories or out of memories and into PCs, there are a lot of places that can glitch and cause a system failure. With newer systems processing more and more data, it will become increasingly difficult to find out what is causing the error, when it happened and how to fix it.
  5. Less Pins Available out of Packages — Even though digital packages are including more and more pins as they get increasingly complex, often times the packages cannot provide enough spare pins to do troubleshooting on a design. As other system components that connect to the original chip also get more intricate (memories, peripherals, etc), they will require more and more connections. The end result is a more powerful device with a higher pin count, but not necessarily more pins available for you the user/developer to use when debugging a design.
  6. Rework — Over a long enough time period, the production of  printed circuit boards cannot be perfect.  The question is what to do with the product once you realize the board you just constructed doesn’t work. When parts were large DIP packages or better, socketed (drop in replacements), changing out individual components was not difficult. However, as the parts continue to shrink and boards become increasingly complex to accommodate the higher pin counts, replacing the entire board sometimes becomes the most viable troubleshooting action. Environmentally this is a very poor policy. As a business, this often seems to be a decent method (if the part cost is less expensive than the labor needed to try and replace tiny components) but if and when the failures stack up, the board replacement idea quickly turns sour.

While the future of troubleshooting looks more and more difficult, there have always been solutions and providers that have popped up with new tools to assist in diagnosing and fixing a problem. In fact, much of the test and measurement industry is built around the idea that boards, parts, chips, etc are going to have problems and that there should be tools and methods to quickly find the culprit. Let’s look at some of the methods and tools available to designers today:

  1. DfX — DfX is the idea of planning for failure modes at the design stage and trying to lessen the risk of those failures happening. If you are designing a soccer ball, you would consider manufacturability of that ball when designing it (making sure the materials used aren’t super difficult to mold into a soccer ball), you would consider testability (making sure you can inflate and try out the ball as soon as it comes off the production line) and you would consider reliability (making sure your customers don’t return deflated balls 6 months down the line that cannot be repaired and must immediately be replaced). All of these considerations are pertinent to electronics design and the upfront planning can help to solve many of the above listed problems:
    1. Manufacturability — Parts that are easy to put onto the board cuts down on problem boards and possibly allows for easier removal and rework in the event of a failure. It becomes a balancing act between utilitizing available space on the board and using chips that are easier to troubleshoot.
    2. Testability — Routing important signals to a test pad on the top of a board before a design goes to the board house allows for more visibility into what is actually happening within a system (as opposed to seeing the internal system’s effect on the top level pins and outputs).
    3. Reliability — In the event you are using parts that cannot easily removed and replaced and you are forced to replace entire boards, you want to make sure your board is less likely to fail. It will save your business money and will ensure customer satisfaction.
  2. Simulation — One of the best ways to avoid problems in a design is to simulate beforehand. Simulation can help to see how a design will react to different input, perform under stressful conditions (i.e. high temperature) and in general will help to avoid many of the issues that would require troubleshooting in first place. A warning that cannot be overstated though: simulation is no replacement for the real thing. No matter how many inputs your simulation has and how well your components are modeled, no simulation can perfectly match what will happen in the real world. If you are an analog designer, simulate in SPICE to get the large problems out of the way and to figure out how different inputs will affect your product. Afterward, construct a real test version of your board or circuit and make sure your model fits your real world version. By assuming something will go wrong with the product, you will be better prepared for when it does and will be able to fix it faster.
  3. Very very steady hands — Sometimes you have to accept the fact that you messed up and the signal traces on your board and you have to rewire it somehow. My analog chip designing friends needn’t worry about trying this…chips do not have the option for re-wiring without completely reworking the silicon pathways that build the chip. In the event you do mess up and have to try and wire a BGA part to a different part of the board or jumper 0201 resistors, make sure you have a skilled technician on hand or you have very steady hands yourself. And in the event you find yourself complaining about how small the job you have to do is, think of the work that Willard Wigan does…and stop complaining.
  4. On the Chip/Board tools — Digital devices have the benefit of being stopped and started at almost any point in a program (debug). Without being able to ascertain what the real world output values are though, it doesn’t help too much. If in the event you do not Design for Test and actually pull signals you need to probe to the top level then you create a board then there are a few other options. One option is to try and read your memory locations or your processor internals directly by communicating through a debugger interface. But if you are looking at a multitude of signals and want to see exactly how the output pins look when given a certain input there is another valuable tool known as “boundary scan”. The chip or processor will accept an interface command through a specified port and then serially shift the values of the pins back out to you. Anytime you ask the chip for the exact state of all the pins, an array of ones and zeros will return which you can then decode to see which signals and pins are high or low.
  5. Expensive equipment — As mentioned above when describing an RF system measurement needs, there will always be someone who is willing to sell you the equipment you need or work to create a new solution for you. They will just charge you a ton for it. In cases I have seen where a measurement is really difficult to calculate or you need to debug a very complicated system, the specially made measurement solutions often perform great where you need them, but are severely limited outside of their scope. To use the example from before, if you needed a 100GHz oscilloscope, it is likely whomever is making it for you will deliver a product that can measure 100GHz. But if you wanted that same scope to measure 1 GHz, it would do not perform as well because it had been optimized for your specific task. However, there are exceptions to this and certain pieces of equipment sometimes seem like they can do just about anything.

Debugging is part of the job for engineers. Until you become a perfect designer it is useful to have methods and equipment for quickly figuring out what went wrong in your design. Over time you become better at knowing which signals will be critical in a design and planning on looking at those first, thereby cutting down on the time it takes to debug a product. And as you get more experience you recognize common mistakes and are sure not to design those into the product in the first place.

Do you know of any troubleshooting tools or methods that I’ve missed? What kinds of troubleshooting do you do on a daily basis? Let me know in the comments!