Category: Learning

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Analog Electronics Learning Renewable Energy

Switching Regulators and Switching Noise

A background

Switching regulator, buck converter, boost converter, SEPIC, flyback, push-pull, buck-boost… do you know what the heck these things are??? Because I sure didn’t when I was getting back into analog electronics. Now thanks to new interest in power efficient electronics, they are starting to come front and center on the electronics stage. Hopefully this article will give you a better understanding of what they are, what they do, where to use them and issues with noise.

OK, so before we get to the real topic of this post, what do switching regulators do?

Switching  regulators allow you to translate one voltage into another. They allow you to take a higher voltage and translate it to a lower voltage or a lower voltage and go to a higher voltage.

“Eureka!” you cry, “Chris has found the solution to all of our energy needs! We just hook a bunch of these switching doo-dads up and we’ll have unlimited power!”

But no, it’s not that easy. Switching regulators go off the fact that you can take a voltage and translate it to a different voltage, however, the power stays the same (in an ideal case). Meaning if you have 5V coming into a circuit and you have a portion of that circuit that needs to operate off of a 15V supply, you can use a boost converter or something similar and crank up the voltage. Say you have 150 mA (at 5V) coming in, when you convert it up to 15 V, you’ll have 50 mA available to whatever needs the 15V power. Notice in this (ideal) case, the power stays the same (750 mW).

It is a similar story when going down  in voltage. However, there are many more options when moving down in voltage: switching regulator, linear regulator or even a passive element (like a resistor or a diode). You use a switching regulator because they regulate the output voltage (unlike the voltage drop across a resistor or a diode) and they don’t waste power like a linear regulator. If you want to go from a 20 V input down to a 5V output, a linear regulator would just “burn” up that 15V in the middle. With a switching regulator, most of the power is conserved (assuming you are running in the optimized voltage ranges…and there are a ton of different models to choose from so you can find the right range).

Finally, real quick, where are these used? Well, the hot new talk of the town has been renewable energy. “I can get 95% efficiency?” you ask, “Why wouldn’t I pay $4 per chip to do that?”. And really, the power efficiency isn’t just the garbage everyone seems to be spewing these days about saving energy for savings sake…it actually can help you make a better product. If you are in a heat sensitive situation, you don’t want to use a linear regulator to get your required voltage. In the above example if you are going from 100 mA at 20V and the output of the linear regulator is 100mA at 5V…that means you are burning 1.5W just regulating your voltages. With a switching regulator you can save a good percentage of that (for battery or “green” devices) and you can reduce the heat in a sensitive application. Plus, if you’re trying to go from a lower voltage to a higher voltage, you’re out of luck with linear regulators.

Switching Noise

Nothing in life is perfect. Switching regulators aren’t 100% efficient, there are limits to how much you can convert voltages (1000v down to 10V usually isn’t possible…or smart) and even in the best cases a switching regulator will introduce noise into a circuit. For the ways I have mostly used switching regulators (supplies for digital circuits), switching noise isn’t that big of a deal. If you are supplying 5V to a piece of flash memory, the part will probably not care if there is 100 mV of noise “on top” of the 5V signal (meaning the actual power supplied would bounce between 4.9V and 5.1V). Same for supplying power to LEDs or other non-analog situations. However, if there are any measurement components in your design or any even slightly sensitive analog portions, you should consider how the switching noise will affect your output.

So why does switching noise occur? To answer that we really need to look at a switching regulator to understand what is inside of it. To illustrate, I will be using my version of LTSpice, which is free (awesome!). Also to note, there are lots of great programs out there to help you design this stuff (Webench, for example). Just don’t want to leave any of the vendors out, especially when they give out sampled parts. For this example, we’ll look at the LT3755, which EDN (and me by extension) showcased in an article about creating simple LED lighting for your home.  The application here would be to boost an input of 10V to an output of 40V to light an array of up to 14 1A LEDs.

lt3755

Notice the LEDs (D2 in the diagram) are where the final current and voltage is being delivered. The waveform for the inputs and outputs is below:

lt3755_chart_no_i

In this graph we see the voltage at the point above R4 (the sense resistor), which is close to what is being delivered to the LEDs. Notice that the voltage starts at roughly 15V and then shoots up to around 40V; the “on” state when the LEDs would be lit settles around 38V. When the red PWM waveform turns off, the voltage bounces up to the exact voltage (40V) the LT3755 is supposed to be outputting because the LEDs are not draining on the output of the circuit. When the PWM goes back on (to 5V), there is noticeable noise on the output voltage. So why is there noise?

lt3755_chart

If you look at the circuit diagram above, the second most critical component after the regulator itself is the inductor (L1), just to the upper right of the LT3755. Switchers take advantage of the fact that the voltage across an inductor is equal to the instantaneous current through an inductor times a constant (known as inductance). Pulsing current through the inductor introduces the voltages necessary to step the output voltage up to the desired level. Using negative feedback, the controlling chips can output pulses at varying speeds and shapes to correct for any errors on the output of the circuit (see the image above to see the current going through the inductor in light blue). However, as stated before, nothing is perfect. The bandwidth of the chip (the op-amps and other controlling elements within the chip) are finite, so there cannot be perfect control. This introduces noise on the output of the circuit at the same frequency as the switcher (and some harmonics of that frequency).  In the LT3755, the switching frequency can be anywhere from 100 kHz to 1 MHz.

If you are using this switcher for LEDs in a car…no big deal. And really, with high power applications such as lighting, the noise isn’t much of an issue. However, as switching regulators find their way into more and more products, the noise issue becomes more prevalent, especially smaller products. The trade-off comes in when you start looking at the inductor required for the switching regulator. Some can get quite large and unwieldy, especially for handheld products (see below for an unwieldy example).

So instead of using a large value (and size and price) inductor, the switching frequency needs to increase. As explained before, voltage is created across an inductor by forcing pulses of current through the inductor. The higher frequency means that there are smaller current pulses, but there are more of them. This allows for smaller and smaller inductors in designs (some are starting to be pulled into the chip packaging!) but brings with it the noise, now at a higher frequency.  If you have a 5V power supply line with 100 mV of noise of top of it (with the noise at around 100 kHz), then it might not be a problem on your circuit board. But when your boss tells you to start using smaller parts so you can fit the design in a handheld form factor and the switching frequency goes up to 1 and 2 MHz, you will start having problems. That innocent 100 mV from before now might couple into other board traces and introduce noise into the rest of your design. If you have any analog signals that are critical to your design, 100 mV of noise can wreak havoc on the output.

Less noise, more answers

Switching noise is something that will be apparent in any design involving a switching regulator. Knowing your system constraints will allow you to best decide which option is best for your specific needs. If you are crunched for space, you will need to be able to handle high frequency switching noise. If you are sensitive to noise, you better buck up for some big, expensive inductors and carefully route your board (in fact, if you’re that sensitive, maybe reconsider switching regulators entirely). If you have access to the resource, the best people to ask are the vendors selling the parts; they know the funny behavior of a part and which “flavor” of regulator to use to best suit your needs. And in the meantime you can play around with the tools they make available online and in software.

Please leave any questions or comments you might have and good luck with your new designs!

Categories
Engineering Learning Life Work

Yes, I’m still here

It’s 2009.

More importantly I’m still employed. I actually had a blog post planned out for early January in the event that I lost my job. Hey, if you’re not going to promote yourself, who will?

I was reviewing my new years resolutions from last year and I realized the only one I really followed through on was finding new employment. And since finding my new employment and starting a blog and all of those details, I have come to some important realizations, mostly about work:

  1. If you’re doing it right, there are 3 sections to your life: sleep, work, other.
    • Sleep is unavoidable. At least for now. If there are ever advances in sleep technology that allow people to sleep less per night (besides coffee), I will be the first in line. Plus, I have come to the realization that without the sleep component in your life, you enjoy the other 2/3 much less.
    • Other is everything you’re not doing when sleeping or working. The most important thing you should be doing (in my opinion) is building relationships in your life and enjoying those relationships. Sure, there are hobbies and time for relaxing and whatnot, but really it’s the connections in your life that will enrich your “other” time. And in this economy, you shouldn’t be planning for too much “other” time, so savor what you get. Heck, I consider this blog to be under this time category and in the event sleep and work  and my family and friends get in the way, the blog will fall behind.
    • So work takes up that last 1/3 of your life…probably more. What I’m trying to get across is, it’s important, much more so than I was ever told when I was deciding what to do with my life. It’s important to enjoy what you do, who you work with, how fulfilled you are by the things you accomplish and having an employer that respects your non-work time. For me, I continue to tell myself that on mornings when I’m walking the dog in the snow or when I glance at the forecasts for my old hometown. I think about how I enjoy my job now and how I let that trump some other things when deciding whether or not I wanted to change my life around and move up t0 the blustery north. And given the choice, I would do it all again and have advised others to do the same (pick up and move across the country for a job they might like).
  2. A job that pays you to learn is probably one of the best jobs in the world–I’m not talking about being a grad student (although that’s not bad either). I know those jobs and assistantships pay you (sorta) to learn and do research and such, but my experience has been in the private sector; jobs where the real expectation is that I produce an item that can be sold for the company. However, the important thing is that you learn in the process.  My job is particularly well suited to learning, mostly because I am handed problems and then told to start fixing them. Jobs that require thinking on your feet and quickly adapt to your situation will give you the steepest learning curve and you should relish the opportunity to be challenged like that.
  3. If you learn new skills, you’re not a commodity anymore–Let’s face it, we’re all afraid of losing our jobs at one point or another. I’d say a higher percentage have that fear now that we’re in a recession. I was talking recently with a friend that just lost her job and she mentioned a similar thought: to stay employed, you have to be valuable to your employer. A simple but powerful concept. In the end if you’re not learning and are not contributing (or not showing off what you do contribute), you are expendable. So in the event that you are in a job that does not allow for learning (either mentored or self-learning), push your employer to let you start new projects that will allow you to do so. If they say your workload is too high, offer to work overtime on your learning project. I think it’s that important and it might just help you save your job.

The recession will deepen. But even in the Great Depression, with 25% unemployment, that meant three out of four people were working. I plan on being one of those 3 by continually increasing my skillset in my work projects or in my “other” time (reading new books, working on my piano and blogging). What are you doing to make yourself more valuable to your employer or to any future employer?

Picture by _neona_

Categories
Analog Electronics Digital Electronics Engineering Learning

Designing For The Long Term

I was at the gym the other day and glanced over at a fellow gym-goer on their cellphone. I did a triple take as the phone was a flip phone that was maybe 4 inches wide and 5 inches high on each flap of the flip (making a 10 inch phone when completely extended).  On my third glance at this monstrosity of a phone I realized it was in fact a Blackberry that he had pulled out of it’s case/holder but the case looked like the bottom half of a flip phone. It got me thinking about design longevity.

I think back on the cell phones of the past and recent past and remember how clunky and awkward they were. That was maybe 5 years ago and those phones have long been sitting at the back of peoples’ desk drawers or hopefully donated to causes that recycle phones. I am amazed that these phone manufacturers continually get away with phones that will be obsolete in 5 years maximum. Why don’t we expect more from our mobile devices (in terms of longevity)? Do we really think your phone will last more than 3 years?

My most recent phone just passed away after 2 years. In my case I MAYBE dropped my phone in a bowl of soup, but I think it just got one of the external speakers; really I think the kiss of death was something a bad battery (which was not contaminated with soup). But even if it lasted another year and THEN died, would I have been upset? I don’t think I or most people would be because we have come to expect consumer products to have a shorter life span.

How do we design electronics for the long term? There are a bunch of great examples of electronics that have been built to last:

  1. Military designs –Aside from the humongous budgets that most contractors have for their military products, the specs on military designs can be equally large in scope. Translation: The military gets high quality products that were expensive but are built to last. These products are often ahead of the technology curve (thanks to the money available), so the technology often goes obsolete later too. The final piece is that the harsh environments encountered by military personnel requires gadgets that are sturdy enough to last for a long time; the ones that function in the field can continue to do so for a long time. A good example would be this emergency radio which was recently torn down by EETimes after an eBay purchase. The 1950s internals reveal high quality workmanship with components that match.
  2. Space designs — Although NASA’s budget has been cut back since Bush has taken office, this research intensive organization has produced some of the finest inventions for human kind. Not only that, they have a mandate to create equipment that can last for long periods of time. My favorite example is the Voyager 1 satellite, currently exiting our solar system and headed further than any other human instrument has ever been. Not only that, but this advanced spacecraft started taking up close pictures of Jupiter and Saturn before I was even born (first passed Jupiter in 1979). The fact that this machine is still functional, still running tests and still capable of sending back data until 2025 (est.) is mind boggling. Not only that, but the spacecraft has not had the advantage and protection of the earth’s ionosphere, so it has been taking much more direct cosmic radiation than normal electronics.
  3. Power companies — These terrestrial behemoths don’t have to worry about cosmic radiation quite as much as the NASA folks, but they often have materials carrying hundreds of amperes of current over long distances. Unfortunately, these systems are in need of some updating (especially to accommodate new renewable energy resources onto the grid), but once they are built, I’m sure they will hold up. Usually power companies achieve longevity in their equipment by using high quality, high strength materials that are designed with enough overhead to manage higher loads that they expect to see (i.e. A copper wire that is designed to carry 1000A of current, but only carries 600A on a regular basis).
  4. Nuclear Facilities — Some of the remnants of the Cold War include the control systems that decided whether missiles would fire or not. These are still some computers operational today in Russia that (we hope) are still making logical decisions. While I don’t agree with these computers in the first place, I sure hope they continue to hold up, otherwise it will prove to be a doomsday device. Proper shielding from radiation and free radicals help to prevent aging damage to electronics from fissile material, in addition to starting with high quality, military-grade products.
  5. Autos — While the auto industry might be falling on its face currently, the designers in Detroit used to help drive new technologies in many other walks of life. Looking at cars that have lasted since the 50s and beyond, we see examples of simple yet elegant electrical designs that were meant to last. Cars have not always had the GPS systems of today (which I’m guessing will have a much shorter lifespan), but have had electronics powering the wiper blades and the spark plugs for a long time. These systems in vintage cars require some maintenance and the occasional fuse replacement, but on the whole are sturdy enough to continue powering well-cared for vintage vehicles.

So these industrial/military and some commercial applications obviously present the need for longevity in finished products. However, designers need to consider many different parameters of a system in order to produce the best product for the long term.

  1. Communication protocol — This item applies most directly to cell phone makers and is a decent excuse for their short life products (but does not excuse everything about them). Unfortunately for phone users (and fortunately for phone makers), wireless protocols are always changing in order to try and achieve the highest bandwidth, usually through higher frequencies or different transmission methods. So once a technology changes for good, older phones become obsolete (and the phone makers happily sell you a new shiny one). This problem also exists when looking to the internals of products; to prevent obsolescence due to outdated protocols, they should be standard to the industry in which the product will be used, simple enough to incorporate into a new standard (and included legacy support) and well documented. Nothing is worse than having a 20 year old device that works fine but can no longer transmit information. An example might be an industrial test fixture on an old computer that only has a 5.25 inch floppy drive. The test fixture might work great, but getting data off that computer is no longer viable so the entire setup is obsolete. A tried and true method for machines to communicate has always been serially and with good reason. While a newer communication protocol might require myriad signals that are not available on an older product, most improvements to a serial signal are often speed (increasing the frequency of the oscillator driving the serial line) or encoding. Since devices can be re-programmed to send a new encoding or you could slow down the device on the receiving end, serial communications seem to be a viable solution for lots of applications.
  2. Long term drift of components — Designing for 10’s of years often requires attention to detail and deep pockets. The most important first step is to watch for this parameter on a data sheet for any critical component (marked as “long term drift”, often given as a percentage change over a specified period). But beware, many vendors simply leave this data off of their spec because they either do not think it is relevant, do not want to display poor data or because they don’t know what it means. In any of these situations it is critical to demand this data or to perform testing yourself in order to create lasting products.
  3. Susceptibility to thermal stress — Size matters when it comes to handling thermal stress; this is partially why older electronics hold up so well. The smaller components on a device get, the less heat they can dissipate (assuming similar materials in a larger package). A good example would be resistors. A 0603 resistor (.6mm x .3mm) can only dissipate 1/10 of a watt while a standard through-hole component can dissipate 1/4 watt on average. This is a trade-off that must be made in any system designed for portability, but could result in lower product lifetime (especially in high heat or high current situations).
  4. Standard packaging — The chip industry is a highly competitive environment where silicon designs are always being touted as the next best thing. Unfortunately for older products, this can often mean that components such as op-amps or a buck converter will no longer be produced. It’s a symptom of being in a dynamic industry and has to be dealt with. The best way to combat obsolescence is to create projects that have standards designed in to them. Thinking about creating a great new analog circuit with a non-standard pin-out in a device package that is so obscure that you have trouble finding it in catalogs?  Why not try making some other compromises on your circuit board and squeezing in a proven SOIC-8 with a pin-out similar to 4 other op-amps. You’ll be happy you do in about 4 years when that op-amp you’re using goes obsolete.

There are probably other ways to help design a product with a long life span, but these are a good start. A common theme is to pay more for higher quality components, which might not be preferred in certain situations. However, designing products for the long term can help save money year after year by not having to replace products or maintain sold products so spending a little more up front could pay off in the end. Some newer consumer electronics industries create new products each year either to drive demand or to fulfill needs after older devices break (which they may have produced).  In the process, they try to drive cost down by using the cheapest parts available; this can cause failures and unhappy customers. To design a long term product, costs and long term design considerations must be balanced.

What’s the longest period you’ve ever had a piece of functioning electronics? What kinds of changes did you see over the years? Have you ever created a low cost design that lasted more than 5 years? Let me know in the comments.

Categories
Analog Electronics Learning Music

Update: Wurlitzer 200A–Still in pieces

I thought I would update on my hobby subject for tonight since I mostly worked on my Wurlitzer 200A electric piano instead of writing the post I meant to. I’m just now getting back into working on my electric piano after previously having zapped something on the board and not being able to get it working since. When I messed up last time I was actually trying to replace the capacitors and transistors that had dried up; I had thought these were causing considerable hum in the circuit. However, since deconstructing the piano I found a modification to the wiring scheme between the two speakers and the output headphone jack located at the bottom of the board. I found that on the headphone jack someone had wired in a simple RC circuit, presumably for filtering the headphone output. However, the small wiring scheme they used and meant to ground to the chassis had been disconnected, possibly by me. This floating output circuit could have been the problem all along! Only time will tell but I will feel silly if that was indeed the culprit.

Still, I always prefer a silly mistake that is found and easily corrected (with damage only to my ego) , as opposed to a difficult error that cannot be fixed or worse, found. See the pictures below of the destruction that has befallen my piano and hope that I can get humpty-dumpty back together again.

The main board, removed from the chassis. With new electrolytic caps.

The piano with the chassis and the board removed. The speaker assembly and the transformer are all bolted to the main chassis, which is convenient when you want to work on the action of the keys (how the hammer hits the tone bars).

The slew of new components I got in from my online order…and now may not need?

It’s not the wand, it’s the magician. In this case, the wand is a piece of junk soldering iron from Radio Shack. Maybe Santa will bring me an industrial voltage controlled soldering iron.

Categories
Analog Electronics Learning

Best Free SPICE Program

One of the biggest conflicts of interest in the life of an analog engineer is that the best tool available to them is on a computer. SPICE is a program that was originally developed at Berkley to model silicon level physics to help prototyping (similar to “bread-boarding”) before the final product was produced. While it still remains a valuable tool for chip designers, it has also been broadened in scope and size to include larger designs and higher level models since it was first created. The idea is the same, that electrons basically move in the same way and that potentials in a circuit (voltages) can induce a certain behavior. So as long as the models for high level components (say an op amp or a buck converter) are well thought out, they often can represent the real world equivalent quite well.

I have some experience with SPICE and it is very helpful for both creation of new circuits and analyzing existing circuits for weaknesses.  And since I have started using it, I have tried many different versions and deviations on the original SPICE program, but I have found I like LTSpice the best. Best of all, it’s free. Like, really free. Even if you don’t know anything about circuits (analog or otherwise) and only plan to use the program once, it doesn’t matter!

LTSPICE IV — Free download! (not sponsored, I just really like the free-ness of the program)

I’m going to try my best to resist making this post sound like a puff piece, but I’ve only recently discovered LTSpice and I really enjoy how it works (even compared to similar programs that have licensing feels). The interface is the exact same as LTSpice III, so if you know that program, you won’t have much trouble with switching over to the new version.

Let’s go over some of my previous complaints about the program and how they have been been put to rest:

  1. No central area to enter model information — One of the things I had enjoyed most about the SPICE programs I had used previously was that there was a central location to put all of your model files for any models of components you might have had. Then when you were ready to use DXYZ123 in your schematic, you just match the component type (Diode, Transistor, etc) and then name it the same as your text file. In LTSpice, you have to enter the model information on the front page as a SPICE directive. While this is similar to putting the models in a separate file, if you plan on using a lot of non-LT parts in your design, your schematic can get quite cluttered.
  2. Harder to create high level schematics — OK, this was really me. I was used to different hot keys in order to modify the schematic. Really this was my impatience at learning a new system, but once I did, it’s not too bad entering new information.
  3. Only Linear Tech component models — While this is a bit annoying, it is also quite understandable since they are giving you a complex SPICE modeling program for free. There are some common passive components throughout, and you can add to libraries to add even more passives, but once you get into active parts, they are exclusively LT. See point number 1 above in order to add models for Analog Devices, National Instruments, Maxim, etc parts.

OK, enough of the downsides, let’s go over what I think sets LTSpice apart from its more expensive competition:

  1. Power consumption calculation — Hold down the alt key and on any component in your schematic and you can map the power consumption on the simulation graph (see below). This equation can be quite complicated, especially for the models that are included for all of the LT parts. As power saving techniques become more and more important to electronics manufacturers, this feature becomes indispensable. If you’re not too big on efficiency but happen to care about temperature, this same feature can estimate how much energy (still in Watts) the individual components will emit based on the power dissipated. At the very least, even if the simulation is not exact in how much power is burned during processing of a circuit, you can graph the rates of all power consumption and see which is the biggest consumer and try to optimize that part.
  2. Efficiency calculation — Again, this will become more and more important to engineers as the focus on simple fixes in products for energy efficiency becomes more prevalent. Here you have to name the input and output signals specific nodal names, but once you do, the program will automatically calculate how much energy is being converted into useable energy and how much is being wasted. An example would be in a circuit made to regulate 10V down to 5V. This can be done with efficiencies up to 90%, but some amount of energy will be dissipated by resistors or active components like op-amps. Ya gotta spend energy to make energy.
  3. Dual Core integration — This is one of the biggest improvements from LTSpice III (really it was called SwitcherCAD III) to LTSpice IV. Now they have support for dual core processors which are quickly becoming the standard in computers from desktop to laptop to netbooks (OK, not yet on netbooks). Either way, if you are only using one available core for your simulations, you’re running at roughly half of what they COULD be running at. I have a dual core on my current machine and LTSpice quickly used up the available resources and the quickness of results showed the difference. LT is still working on the bugs on some types of computers processors, so they only run on one core, but hopefully it will be functional on all types of machines soon.
  4. Graphing function — This isn’t any different from LTSpice III, I just thought I should mention how much I like the graphing abilities of this program as compared to others I’ve used. LTSpice really grabs hold of the graphic model in SPICE and runs with it; their software allows you to click on a node to find out the voltage (even after the simulation is completed) or to click on a particular component to find out how much current has gone through that part throughout the simulation. The point and click method allows for quick diagnosis of problem components and circuit layouts.

  5. Dynamic Simulation — Linear Tech is a big player in the switcher market (a switcher basically takes input power and pulses an output–usually through a capacitor or inductor–to produce a stable output). However, the side result is that their program is well suited to handle rapidly changing inputs. I plan to re-construct my Wurlitzer 200A schematic in LTSpice in order to better understand some of the parameters affecting the sound and maybe even inputting and outputting sound files (you can do that with raw formats). More on that in later posts.

All and all, I know I sound like I’m gushing, but I always enjoy free software that is made well. It’s like some of the open source programs I love, but with a company behind the product supporting it (and yes, trying to sell you chips).  There are many other great SPICE programs out there and some of very worth the fees they charge. However, if you are looking for a quality program at no cost, I would suggest LTSpice.

Do you know of other SPICE programs? Do you like them better for one reason or another? Please let me know in the comments section.

[xyz_lbx_default_code]

Categories
Blogging Learning Life

Yeah I’m Thankful

OK, so I know that just about everyone else on the internet is doing the same today (I’ve read them), but I thought I would also say what I’m thankful for.

  1. My Girlfriend — I know I am consistently annoying by staying up late writing and sometimes during the few hours we have to spend together after work. My wonderful girlfriend has always been accepting of my interestingly nerdy habit of coming home from working on electronics to…write about working on electronics. I appreciate her patience and her understanding along with everything else she does for me.
  2. My Family — What can I say? Not only was I born into a demographic with more opportunities than most, I was also blessed with a family that encouraged my interest in science and learning. I appreciate how they pushed me to read at a young age and then nurtured my interest in creative toys (Legos, TinkerToys, etc), even when I left them laying around.
  3. My Friends — My buddies are kind enough to support me when I’m complaining about silly stuff like not getting blog exposure and are real troopers who bother to read my blog on a regular basis. Without them, I’m sure I would go crazy and I really appreciate having them around.
  4. Electronics Pioneers — Aside from thanking my loved ones, I really wanted to write this post because when I think about the progress that has been made to get the human race to where we are, it’s quite amazing. From the early inventors who developed the math that allows us to calculate what we do, to the first testers of transistors and up to the people that helped create software 10 years ago. What’s more, I’m very grateful that they have provided me with the tools to do my job today (such as graphing calculators, SPICE, MATLAB, etc) so much easier and on such a higher level because of all the hard work they did with their slide rulers and look up tables.
  5. The Internet — Similar to the above point, I am very thankful that there are tools available to me on the internet that allow me to get my ideas out with very little hassle. Prior to WordPress, I had tried to start websites many times. After finding simple publishing software, I was able to get my thoughts onto my site with no issues. I also have the opportunity to easily do research on topics that interest me and connect with others interested in similar topics.
  6. My colleagues — In all my jobs, I am thankful for people that take the time to show me new techniques for solving problems or ways to better approach an issue. As an engineer gaining more experience, it is inspiring and makes me want to share knowledge I have with younger engineers. If you happen to be a younger engineer, I would take this opportunity to encourage you to find those willing to help and use them as a resource. Oftentimes it seems like you might be bugging someone or that you should be able to solve something on your own, but asking an experienced person will often give you a new way to solve a problem with a completely different approach than you would have normally used.

So thanks to all those listed and all those I forgot. Have a great Thanksgiving and enjoy the madness of the holiday season that is now upon us!

Categories
Economics Engineering Learning Life Work

On Job Losses and Stem Cell Engineers

Like any good mortgage-fearing first-time home buyer, I worry about my income sources and my job. I don’t have any fears based on performance, but just general fears. It seems that the possibility of recession I wrote about back in September is here and it doesn’t look like it’s going anywhere for a while. So what can I tell you to try and put your mind at ease (“you” of course being an engineer or someone interested in the fate of engineers…I have no authority on other job types). I can tell you what I was told when I was nervous today:

You’re going to be fine. (Helpful, right?)

The great thing about being an engineer, and specifically a relatively inexperienced engineer, is that you’re desirable because you’re flexible (mentally, of course, unless you’re one of those weird gymnast/engineers). You can easily come into a new role that you may know very little about and quickly learn the task. This is not to say that others are not capable of doing the same; many individuals are very good at this concept and are known as “polymaths” (people who excel at many different disciplines, a great example being Leonardo DaVinci). No, I speak of engineers as being mentally malleable because that is the main skill they are taught in school. If an engineer learns nothing more in school, they should learn to teach themselves.  This is why I think of new engineers like stem cells; they naturally adapt to those around them to perform a similar task. However, the longer they stay in a position or field, the harder it gets to leave that field.

So in an effort to calm me down (he did), my friend pointed me to a piece of advice he received from a former colleague, who I also knew. This person was and is a great all around engineer (mechanical by title, but knew his way around electronics) and had the following to say (paraphrased):

As long as you’re willing to work hard, you’ll be OK in the end. At times, you might not like every aspect of your work you’re doing and at other times, you won’t get paid what you deserve. But come good and bad, if you work hard and are open to learn whatever is required to get the job done, you’ll be OK.

My friend told me that this talk he had with the experienced engineer has stuck with him and it’s easy to see why. A veteran engineer who had re-invented himself many times over was living proof that when times get tough, the tough get learning. I guess in the end this is kind of stating the obvious; if you are willing to do anything to get by, you will get by. But I think it is interesting in the context of this blog because when engineers lose a job or are stuck working only contract work, they think there are no other options. Instead, they could be looking at non-traditional roles for engineers, explaining how they can apply their past experiences and hope that the hiring manager recognizes the flexibility most engineers have and puts them to work. I think of a situation where a power engineer cannot find work and ends up in a power line technician position. Not only would the engineer be temporarily employed, they would be able t experience many of the problems that their customers or end-users experience every day. In the best case scenario, the engineer would be able to take that knowledge back and design a better product.

So what do you do if you are an engineer and out of a job currently? Perhaps try a related field that can be used as leverage at your next job. I think of my time working in a semiconductor fabrication facility this way; I was not working on the design of the product, but I got some hard skills (mostly statistics), some soft skills (working in a high pressure environment independently) and some undefinable skills (a sense of where the semiconductor business is heading and how it could affect the market). If you happen to work in a field that is so niche that you cannot find anything remotely similar to what you prefer to work on, maybe try taking a traditionally lower level job in your field and try working on more hands-on type activities (similar to the power line example above). You can work to hone your existing skills and hopefully rise quickly as you show how proficient you can be. However, if there are not any engineering positions available, it is likely there will not be these lower level jobs available either. So in the most dire of straights, try for something completely different. Since starting my blog I have become increasingly interested in marketing and how to create a brand. If there came a time that I could not find engineering work, I would try and target marketing as a near choice–not because I have any relevant experience (I don’t)–but because I think that the skills I would pick up would be helpful at unknown points later in life.

As for non-engineers out there, I can only speak good things about engineering and the job prospects throughout a recession. As I always do with younger people asking about engineering, I can quickly lay out some reasons to become an engineer (and would be willing to do so more if you have more questions by email). You have the flexibility to do a wide variety of tasks and have the opportunity to positively impact the world. You can choose among a wide variety of professional fields or stay in school and teach others engineering skills or do research in a university setting. There are many naysayers who claim that you will not be in charge on projects, but you could always choose management if you want to run the show. Others will say that you will not get paid what you deserve; but I think that remembering engineering is about helping people is important. Not only does it discourage those who are only in engineering for the money, it also helps remind you that your goal should be to help others.

So I know this post spanned many aspects of engineering but I think the main idea is that as an engineer, you can survive a lot of what the economy throws at you. Hard work and mental flexibility will let engineers re-invent themselves if necessary and prosper in the most volatile of economies. If you have experienced job safety or, conversely, have been pushed off an employment cliff thanks to your engineering degree and you’d like to share, please leave your thoughts in the comments.

Categories
Analog Electronics Learning Life Renewable Energy

Buying a House and Making It More Efficient

So usually I don’t like to write about my personal life on here too much, but I had an offer accepted on a house yesterday and I think it’s relevant to topics discussed on this site. Yes, I realize that the housing market is down and that it will likely only get worse. And yes, I realize I’m young and a house is a big responsibility. And yes, I know home ownership can be a daunting experience from upkeep to sales to everything else bad that can happen. But there are some great things about houses too, namely tax advantages and being able to do whatever I want with it (within reason). Plus, I feel that every home can take advantage of advances in conservation and renewable technology, even if they are already in good shape and the energy bills are low.

  1. Insulation — A no brainer, this is a great way to reduce the amount of energy leaving your home. A friend and I were talking about older houses and he made a good point that houses built in the 50s didn’t always worry about insulation. It was decently inexpensive to just crank up the heat. Now with gas prices rising (don’t worry, this temporary lull won’t last), it becomes a necessity to conserve the energy we burn. My friend also mentioned a possible tax break that exists; if not, I would hope the next administration includes something in their renewable energy plan. Remember, conservation is the cheapest method of energy savings right now.
  2. Windows — One of the most frustrating things in cold weather is walking up to a poorly insulated single pane window; it rattles, it frosts and it let’s chilling temperatures through. Windows are one of the best ways to lose heat and waste energy in the winter, especially in the great north. It feels like it literally is sucking the heat from your house. Sure, double pane and triple pane vinyl windows are a good start and will stop 90% of your heat loss. However, A great story on NPR about legacy technology from the 70s tells about how a simple coating can stop heat loss in the winter and block heat from coming in during the summer. The low emissivity (or “low e”)coating basically just blocks out infrared radiation from getting through (think of those waves you see rising from blacktop on a hot summer day). Windows were already proficient at blocking convective heat flow (think warm air), but the radiative piece was missing. Look for the low e rating when purchasing your windows and you could see some significant energy savings.
  3. Efficient Devices — Every time the compressor kicks on for my current refrigerator, I can’t help thinking about how much electricity is being wasted to keep my food cool. While it isn’t great to throw out the old clunker fridge just to buy a new shiny energy STAR certified fridge, it might be better in the long run to get something that will save energy (even at the cost of greater consumption). If you’re really crafty, you can always turn that old fridge into a meat smoker (think ribs), a bookshelf or even a planter. Remember, don’t just throw the old fridge in the basement and keep running it for frozen goods. If it’s truly an energy vampire, unplug it from the wall and find a different use for it.
  4. DC Power Outlets — Instead of plugging in cell chargers that are burning power no matter if you are charging something or not, why not have a few lines in your house that are set to a specific voltage, say 6V (most devices are running 3.3V these days). Then when the 6V comes to the wall, you could have a “tuner” based on a buck converter that would dial down that voltage to the one you need. Delivering power from a central source could be controlled remotely, so you could close a relay at the source and no power would be delivered to the converter unless “asked for”, and there would be very low losses in the system.
  5. Solar panels — I wrote last time about GreenField Solar and their new solar concentrator, which is very reasonably priced and could pay itself off in less than ten years if it works as advertised (1500 W output). However, in northern climates, it’s often better to get more total exposure by having a larger array of panels collecting the most light possible, even if at lower efficiency. This requires more space of course, but you might be able to get lower cost panels if they are older and assumed to be less efficient. A friend and and I are talking about trying this in the backyard (which is sizable) and doing some measurements on the power we could harvest even in the Cleveland winters. The eventual goal would be enough to power a shed or outhouse for a small music studio, but that will take some work. Wind might be a better candidate, but that would require more infrastructure (AC-DC conversion) and the turbines are still quite expensive (if not beautiful and artistic in some cases).
  6. Do an energy audit — Sometimes the places where you waste the most energy are the least expected. Have an electric water heater? You might be paying out the nose for your showers and washing dishes. Air conditioning unit more than 10 years old? Maybe that’s pulling hardest at your electricity usage. Do you own a programmable thermostat (the kind that shut off heat when you’re not usually home or asleep)? This simple device will save you hundreds in electricity and natural gas savings. Energy audits are usually offered for free by your energy companies. Look them up and take advantage.

So part of me is terrified at the prospect of owning a home but the other part is pretty excited about what I can do with it. I think using it as an example for simple home fixes and ways that analog electronics projects can help to save money and carbon emissions will be good for my conscience and for this site. If you have any ideas on home projects, please leave them or a link to them in the comments.

Categories
Analog Electronics Digital Electronics Engineering Learning Life Work

How to get a job as a new electrical engineer grad

I was going to call this post “A portrait of an electrical engineer as a young man (or woman)” but decided against it. I’ve got nothing on James Joyce, neither in loquaciousness nor confusing writing.

Anyway, I have been pondering what kind of employee I would hire out of school for an electrical engineering position. There are some basic skill sets that will allow just about any young engineer to succeed if they have these skills (the best situation) or at least appear they will succeed if written on their resume (not the best situation). Either way, let’s look over what a new grad should have on their utility belt before going out into the scary real world.

  1. Conceptual models of passive components — This has been one of the most helpful things I have learned since I have left school…because this kind of thinking is not taught in classrooms (at least it isn’t in the curriculum). The idea is to conceptualize what a component will do, as opposed to what the math is behind a certain component or why the physics of material in a component give it certain properties. Why does this matter? When you’re looking at a 20 page schematic of something you’ve never seen before, you don’t care what kind of dielectric is in a capacitor and how the electric field affects the impedance. Nope, you care about two things: What is the value and how does it affect the system. The first question is easy because it should be written right next to the symbolic notation. The second is different for each type of passive component you might encounter. Let’s look at the common ones
    • Resistors — The  best way I’ve found to think of resistors is like a pipe. The electrons are like water. The resistance is the opposite of how wide the pipe is (if the resistance is higher, the pipe is smaller, letting fewer electrons through in the form of current). Also, the pressure (voltage) it takes to get water (electrons, current) through a pipe (resistor) will depend on the thickness of the pipe (resistance). Well whaddaya know? V=IR!
    • Capacitors — At DC, a capacitor is essentially an open circuit (think a broken wire). If you apply charge long enough (depending on the capacitance), it can consume some of that charge; after it is charged it will once again act like an open circuit. When considering AC (varying) signals, the best way to think about a capacitor is like a variable resistor. The thing controlling how much the capacitor will resist the circuit is the frequency of the signal trying to get through the capacitor. As the frequency of the signal goes up, the resistance (here it is called “impedance”) will go down. So in the extreme case, if the frequency is super high, the capacitor will appear as though it is not there to the signal (and it will “pass right through”). Taking the opposite approach helps explain the DC case. If the signal is varying so slowly that it appears to be constant (DC), then the impedance of the capacitor will be very high (so high it appears to be a broken wire to the signal).
    • Inductors — Inductors have an opposite effect as capacitors and provide some very interesting effects when you combine them in a circuit with capacitors. In their most basic form, inductors are wires that can be formed into myriad shape but are most often seen as spirals. Inductors are “happy” when low frequency signals go through them; this means that the impedance is low at low frequencies (DC) and is high at high frequencies (AC). This makes sense to me because if the signal is going slow enough, it’s really just passing through a wire, albeit a twisty one. An interesting thing about electrons going through a wire is that when they do, they also product tiny magnetic fields around the wire (as explained by Maxwell’s Equations). When a high frequency signal tries to go through the inductor, the magnetic fields are changing very rapidly, something they intrinsically do not want. Instead it “slows” the electrons, or really increases the impedance. This “stops” higher frequency signals from passing through depending on the inductance of the inductor and the frequency of the signal applied. Looking at the how they react to different frequencies, we can see how inductors and capacitors have opposite effects at the extremes.
    • Diodes — I think of diodes as a one way mirror…except you can’t see through the one way until you get enough energy. The one way nature is useful in blocking unwanted signals, routing signals away from sensitive nodes and even limiting what part of a varying signal will “get through” the diode to the other side.
    • Transistors — I always like thinking of transistors as a variable resistor that is controlled by the gate voltage. The variable resistor doesn’t kick in until the gate voltage hits a certain threshold and sometimes the variable resistor also allows some energy to leak to one of the other terminals.
  2. C coding — Sorry to all you analog purists out there, but at some point as an engineer, you need to know how to code. Furthermore, if you’re going to learn how to code, my personal preference for languages to start with is C. Not too many other languages have been around for as long nor are they as closely tied to hardware (C is good for writing low level drivers that interpret what circuits are saying so they can talk to computers). I’m not saying higher level languages don’t have their place, but I think that C is a much better place to start because many other languages (C++, JAVA, Verilog, etc) have similar structure and can quickly be learned if you know C. Even though the learning curve is higher for C, I think it is worth it in the end and would love to see some college programs migrate back towards these kinds of languages, especially as embedded systems seem to be everywhere these days.
  3. How an op amp works — I set the op amp apart from the passives because it is an active component (duh) and because I think that it’s so much more versatile that it’s important to set it apart conceptually. I’ve always had the most luck anthropomorphizing op amps and figuring out what state they “want” to be in. Combining how you conceptually think about op amps and passives together can help to conceptualize more difficult components, such as active filters and analog to digital converters.
  4. The ability to translate an example — A skill that nearly every engineering class is teaching, with good reason. Ask yourself: are homework problems ever THAT much different from the examples in the book? No. Because they want you to recognize a technique or a idiosyncrasy in a problem, look at the accepted solution and then apply it to your current situation. Amazingly, this is one of the most useful skills learned in the classroom. Everyday engineering involves using example solutions from vendors, research done in white papers/publications and using even your old textbooks to find the most effective, and more importantly, the quickest solution to a problem.
  5. High level system design — This is similar to the first point, but the important skill here is viewing the entire picture. If you are concentrating on the gain of a single amplification stage, you may not notice that it is being used to scale a signal before it goes into an analog-to-digital converter. If you see a component or a node is grounded periodically, but ignore it, you may find out that it changes the entire nature of a circuit. The ability to separate the minutiae from the overarching purpose of a circuit is necessary to quickly diagnose circuits for repair or replication in design.
  6. Basic laws — It is amazing to me how much depth is needed in electrical engineering as opposed to breadth. You don’t need to know all of the equations in the back of your textbook. You need to know 5-10; but you need to know them so well that you could recite them and derive other things from them in your sleep. A good example would be Kirchoff’s laws. Sure, they are two (relatively) simple laws about the currents in a node and the voltage around a loop, but done millions of times and you have a fun little program called SPICE.
  7. Budgeting — There are many important budgets to consider when designing a new project. In a simple op amp circuit, there are many sources of error and inefficiencies. Determining and optimizing an error budget will ensure the most accurate output possible. Finding and determining areas that burn power unnecessarily must be discovered and then power saving techniques must be implemented. The cost is another consideration that is usually left to non-engineering, but is an important consideration in many different projects. Finding cost effective solutions to a problem (including the cost of an engineer’s time) is a skill that will make you friends in management and will help you find practical solutions to many problems.
  8. Math — Ah yes, an oldy but goody. Similar to the passive components, having a conceptual notion of what math is required and how it can be applied to real life situation is more important than the details. Often knowing that an integral function is needed is as important as knowing how to do it. And similar to the basic laws, you don’t need to know the most exotic types of math out there. I have encountered very few situations where I need to take the third derivative of a complicated natural log function; however, I have needed to convert units every single day I have been an engineer. I have needed simple arithmetic, but I’ve needed to do it quickly and correctly. Sure, you get to use a calculator in the real world, but you better learn how to use that quickly too, because your customers don’t want to wait for you to get out your calculator, let alone learn how it works.

Each of these skills could be useful in some capacity for a new electrical engineer grad. There are many different flavors of engineering and the skills listed above are really modeled off what would be good for an analog system engineer (who develop commercial or industrial products). However, a future chip designer and even a digital hardware engineer all could benefit from having the skills listed, as it is sometimes more important to be open to new opportunities (especially given the possibility of recession and potential shifting of job markets).

Did I miss anything? Do you think there are other skills that are necessary for young electrical engineers? What about general skills that could apply to all young engineers?

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Analog Electronics Blogging Health Learning Life Music Politics

Why start a namesake site?

Tonight, I’m using every bit of my being not to post something political (watching the VP debate). The tension in this country is so thick you can cut it up and serve it. Anyway, instead I will post a question (to myself).

Why did I start ChrisGammell.com?

I’ve written before about why I started a blog, but never why I decided to make it a namesake site (using my real name, all over the place). The main reason is branding. Pure, simple and maybe a little bit selfish. It’s actually a lot of work to get people to know your name. It’d be much easier to start a blog titled “AnalogElectricalEngineering.com” or something like that. That would be great for the average Analog Electrical Engineer, but not so much for Chris Gammell. In that case, I would have to work extra hard to let people know who I am and what I do. So why else? I like trying to be an individual (even if it complete individuality may not be possible). I love the idea that people are reading my ideas. I like the attention, sure, but moreso, I like contributing to society, even a little bit. Perhaps it’s a characteristic of Generation Y, but I enjoy it and I’ll spend some late nights to help out if I can. Yet another reason is that I enjoy challenging myself to learn knew things. True, I feel a little guilty blogging about things I’m not a master of, but if I spend some time researching, I can usually point readers in the right direction, even if I’m not completely sure. The best point is where I define a problem for myself online and then figure it out and get to post it later.

It’s a risk, for sure. First off, if I publish some bogus articles, people will know it. Moderators, readers, editors, professionals, everyone is really a critic on the internet. But I’m ok with that because when someone corrects me (hopefully in a civil manner) it’s an opportunity to learn. Plus my ego isn’t so big that I think I know everything (or anything). Beyond the simple idea of being wrong, I’m also giving direct access to a lot of information about myself and my life, even if it is my professional life. I justify the lack of anonymity by thinking about having people coming back and reading my ideas because they recognize my name. If I can inspire some confidence in my ideas, then I’m doing alright. Finally, I take great care to not reflect badly upon those that know me, nor those that are associated with me. In my thus-far short career as an analog engineer, I’ve found that referring other people is a power that should be respected. Not only should you be careful who you refer to others but also how you interact with others so they will someday refer you.

Short and simple, I started a namesake site because of my ego. I keep it going because I love the direction it’s taken me in. I love that blogging is helping me define myself outside of my job, even if it is similar to my job (which I also love).

Why do you blog (or not blog)? Respond in the comments, please!