Category: Analog Electronics

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Analog Electronics Blogging Renewable Energy

Back in March

Hi everyone,

I know there aren’t too many concerned blog citizens out there, but I just wanted to post to say I am taking the rest of the month off from writing to take care of personal stuff (mostly my house). I would highly suggest you leave any blog post ideas you would like to see when I get back on the “skribit” widget on the right side of the page. Alternately, you can vote on suggestions that are already there. I get weekly updates on which post ideas are popular and will use those to build up my post repertoire in order of popularity (most of the time). Thanks for reading, as always, and I look forward to continuing the conversation about analog electronics and renewable energy when I get back.

~Chris Gammell

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Analog Electronics Blogging Life

Blogging Keeps Me Going

As you may have all noticed (or at least those that read here more often-ish), I have been posting less lately. Partly because I am fixing up a new house and partly because I have not felt very inspired. I think the recession is starting to get me down a little unfortunately. Worrying takes its toll as I’m sure many can attest to.  But fear not! I have some things I would like to reaffirm about why I enjoy blogging thus far and why I think it’s a good idea to keep going with the blog:

  1. Resume 2.0 — I have seen it written that blogs are the new resume. I believe that a little bit, but only for certain industries. If you’re in a field like marketing or PR, you’d BETTER have a blog, and it should be better than the other gazillion marketing blogs out there. The people in non-traditional writing fields like engineering don’t have quite as much competition but I’ve never seen whether employers like new hires to write blogs. Heck, some might even discourage it for fear of a leaky mouthed employee talking about the company’s next great patent or product (I’m so much smarter than that though).  Any way you look at it, if you have a blog you are much more visible to employers than those without a blog.
  2. It opens new windows — My site is hardly a high traffic site. However, I get enough visitors that when someone leaves a comment I can take the time to write them back and try to get to know them. Already I have emailed with some people in the industry that I don’t think I would have ever met otherwise. I have had some people contact me for job interviews and others contact me about potential projects. I like that the blog helps me communicate with people.
  3. Build a brand, brand yourself — Chris Gammell is a brand now. It’s a search term. I’m even thinking about making it into an LLP. But when all else fails and people don’t make that association, scream out what you want people to know you are. That’s why I bought Analog ElectricalEngineer.com last month. If nothing else, blogging has taught me a lot about marketing, especially with “New Media”.
  4. Options, Options, Options — I’d like to think if nothing else in this down economy, I might have a few more options than my non-blogging engineering brethren. I think of writing for magazines, trying to blog full time (probably would need more people in the world interested in engineering), consulting, doing contract work, shifting completely and trying marketing (see above) or looking for another engineering position and advertising myself on my blog. While I have learned more and more that it is your experience that gets you a job, the tough part is showcasing that experience to an employer.
  5. Analog electronics suits me well —  I’ll be honest. I feel that my strengths lie in improving upon existing ideas as opposed to coming up with completely new ideas (engineer vs. scientist). And I think analog electronics intrigue me because even after all of these years since electricity was discovered, there are SO many things that are hard to get right. And there will always be problems with analog circuits where others will need help. You can put everything into digital format but there will still be significant portions of a circuit that need to be processing analog signals. Not only that, I could see a future where more signal processing moves back into the analog domain. Ka-ching!
  6. Renewable energy has a long way to go — I love writing about analog because it makes me geek out. I love writing about renewable energy because it’s such a new and exciting field with so much going on and so many new developments. While I don’t like talking about things “going green” just for the sake of it, I really do think there are some significant advances in the technology that need to be discussed (or dismissed).
  7. I like writing — Of all the things that blogging has taught me, I was most surprised at enjoying finding my writing voice. Perhaps it’s my creative side trying to escape or perhaps I enjoy others reading what I have to say. Either way, I like trying to get my ideas across to people, especially difficult technical ideas that may have been inaccessible otherwise. I hope you enjoy it too.

I know this and other posts have been a bit more introspective lately, but I think that’s what tougher times do to people. We stop expecting answers to be external to ourselves and we start to analyze how we can enjoy what we have and what we do. I fully expect to publish more technical entries in the near future because that is something I enjoy doing.

If you have posts you would like to see, technical or otherwise, feel free to suggest them in the skribit box to the right. Others can vote on ideas and I will write them if I can. If you have anything else to say, the comments box is always listening (as am I).

Photo by Woplu

Categories
Analog Electronics Life

Happy Holidays

I’ve been a bit more of a Grinch this year than I am usually at Christmas/Festivus/Hanukkah/Kwanzaa/etc. I think part of it is my worries about the economy and the rest is because I think the buying of presents is good intentioned, but kind of a waste. Once I get past my own soapbox, I often find that I end up with some thoughtful gifts from the ones I love. Let’s get to the part where I am thankful for the gifts I did get:

  1. A book — My gf was kind enough to listen to me complain about being an analog engineer and not having one of the most important books on my bookshelf. She got me Troubleshooting Analog Circuits by Bob Pease. Up until the past few months I never knew who Bob Pease was until an experience co-worker turned me onto his and Jim Williams’ writings. I admire both of them for their extensive experience in the field of Analog Engineering and their friendly, down-to-earth writing style (something I try to emulate). The “Troubleshooting” tome is well known as a guide on how to specifically move towards pinpointing issues in an analog circuit. I look forward to reading it and applying it. I also hope to post a book wishlist/review list in the near future.
  2. Tools — My parents understood that people trying to fix up a house and make it more energy efficient require tools to do so; they got me some great tools. I’m sure those tools will help me fix all the mistakes I make in the house too. I have also decided that Lowe’s/Home Depot/Etc are the Toys R’ Us of the “older kids”.
  3. A Chord Organ — This is a gift from previous owner of the house I bought to me…because they left it in the attic. It turns out this is a “Magnus Serenade”, and so far it has been pretty hard to find any information on it.  I believe that it is a simple chord organ, similar to the other Magnus models. The idea is that you activate reeds or sets of reeds with keys or buttons (respectively) and then an electronic blower forces air across them to produce a sound. Really it’s like a big accordion (without the back pain). I haven’t had a chance to pull it out of the attic to try it out yet, but if it does not work, it will give me another opportunity to work on old musical instruments. The video I’ve included below is a similar model of chord organ…not the best sound, but definitely unique.

Magnus_Serenade_1 Magnus_Serenade_2

I hope everyone had a great holiday and I look forward to continuing to post in 2009!

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 Digital Electronics Engineering

Circuit Board Design (And How It Has Changed)

Products today mostly use Printed Circuit Boards (or PCBs) to successfully route signals from one component in a circuit to the next. There are multiple layer circuit boards with printed metal “wires” that run between the various elements in a circuit. However, this was not always the case. In the good ol’ days, there were different variations and precursors to the PCB. Some of these included point to point wiring (just soldering a wire between say a resistor and a capacitor), wire wrap boards (think of a point-to-point board on a grid with more wires than you’d know what to do with), acid etched copper on dielectric (think of a 1 layer PCB with very large and rounded signal traces) and many others. These kinds of boards had many many different methods but also had less restrictions than modern designs. In fact,  Paul Rako from EDN recently wrote a great article on prototyping using some of these older methods. He references many techniques of the greats like Bob Pease and Jim Williams and their rapid prototyping techniques. It’s an information rich article and I would highly suggest checking it out. OK, back to the party.

So what has changed when moving from older boards and circuit designs to newer circuit boards?

  1. Speed — There’ s no denying that the boards of today are faster than those of yesteryear. The extremes are apparent in the RF industry which is/was doing well because of the cell phone becoming the hottest platform to develop for (PCs are still around of course but the excitement is in the cell phone industry).  When frequencies get into the GHz range and you’re trying to guide signals instead of wire them, you know that your boards will be finicky. Additionally, the speed increase is not limited to the RF industry as many new designs have at least some component of a clocked digital system on them. Even pushing into the MHz range can be difficult with older board techniques. Wiring point to point is not as viable with high speed signals, especially when you have upwards of 32 wires between two components (a data line).
  2. Size/Type of components – This is another symptom of newer industries. As products go increasingly mobile, parts begin to shrink out of necessity or because the cost of making the older, larger parts becomes prohibitive. As such, the boards have made a large change going from through-hole components (like the capacitors in the picture at the top of this site), to Surface Mount Technology. This has affected the construction of final boards (SMT usually requires machine placement for quick and reliable boards). This also means that the amount of power a board containing only SMT parts can absorb (when the board is considered as one entity) is reduced as the smaller SMT parts cannot handle as much current without blowing up.
  3. Number of connections — I’ve included a picture of wire wrap from the Wikimedia commons site below. Notice anything about it? It’s ridiculous! And I would encourage you to go to the Wikipedia page and look into some of the other types of wire wrapped boards. Now let’s look at a common package today, the Ball Grid Array (BGA). This type of package uses little solderballs on the bottom of the package to adhere to the board. It is glued on at first and when you reflow (heat up to make the solder melt), the balls fall into place on whatever PCB you have produced (assuming you have made the PCB correctly).  BGAs start around 144 pins (maybe 196?) I believe and go to upwards of 1000 pins per part. Can you imagine trying to hook up 1000 wires like below? I don’t think so.

  4. RoHS — Lead is bad for the environment, for your health and for any children who decide to ingest it. In fact, the only people who speak the wonders of lead these days are cranky analog engineers such as myself, trying to solder something (I’m a 6 out of 10 on the cranky scale). Why do we love lead? Because Lead-Tin (Pb-Sn) solder is much easier to work with due to the lower melting temperature and higher thermal capacity.  So as RoHS becomes more widespread, with the Silver-Tin (Ag-Sn) solder that is more difficult to work with, it become another element of board design that must change.

So obviously some stuff has changed. Some is for the better, some not so much. Let’s look at board problems encountered in modern day printed circuit boards in order to see the problems encountered as circuit boards have become more inexpensive and repeatably made:

  1. Capacitance in the board — Printed circuit boards are constructed from a non-conducting material so that signals do not leak from one lead to another. However, in constructing the perfect insulator, they also created a material with a significant (but not huge) dielectric constant. This means if two signals are routed over top of one another (acting like plates), then the sandwich of the signal and the dielectric will act like a capacitor. Not only that, but as you increase the frequency of a signal (with speeds upwards of GHz), the capacitor looks more and more like a shorted wire! This phenomenon is known as “cross-talk” and can affect myriad high-speed or high voltage situations.
  2. Inductance in the leads of a chip — Before the BGAs mentioned in point 3 above, there were packages (usually square) with leads coming out the sides known as Quad Flat Packs (QFPs). The leads coming out of them vary in thickness, but usually get thinner as there are more leads on a chip. As the leads get thinner and longer, the inductance of those leads goes up. We remember that inductors are the “opposite” of capacitors in that they allow low frequency signals to pass and block high frequency signals. In a system that is mostly high frequency signals (think digital), the inductance of the leads can have a serious affect on how well a signal propogates from one element on a circuit board to the next. BGAs have started to reduce this problem, but the cost of dealing with BGAs can be quite prohibitive for smaller operations.
  3. Timing — In a high speed system that requires signals to depart a component at a certain time and arrive at a different component a short (predictable) while later, there are many things that can prevent the signal from arriving undisturbed. We’ve already seen the capacitive and the inductive effects mentioned above, but what about resistance?  Although everything has some amount of resistance, the lines in a board routing one component to the next can have an affect on the overall performance of a circuit. If one of these lines is longer than another than there will be a noticeable difference in the resistance of that line. Most importantly, when comparing the impedance (sum of the resistance and the frequency dependance of the impendance and capacitance) of two different lines going between components (say a processor and a RAM chip), differences can cause the signals to arrive at different times in different conditions. The rise times, the fall times, the over shoot, the under shoot, and the general shape of a signal can all be affected by the characterisitcs of the connection. It is useful to remember that every connection really acts like an RLC filter circuit, the only difference being how much resistance, inductance and capacitance are present and how they will affect the final signal.
  4. Ground/Power Plane — Other advantages a circuit board brings, especially multilayer circuit boards, is the ability to route a plane of power or a grounding plane underneath a portion of a design. If we think of a PCB as a large sandwich, the grounding plane would be like a slice of cheese, running underneath many of the different components of a circuit but not necessarily connected to them. If you design a circuit to have “vias” then an example component on the very top of a circuit board can connect down to the plane and access the power, ground or whatever signal happens to be running underneath there. This technique can be quite useful if you have many different op-amps in a certain area that will require positive and negative power supplies. Or if you have a large connector that requires a majority of pins to be grounded, a grounding plane can be useful to quickly connect many signals to the same net. However, as with any system, there are real-world consequences to deal with; in this case, we have to deal with electrons acting like electrons. With grounding planes, all of the pins on a board that are tied to ground will technically be at ground, however if one pin happens to have a large current going into the ground, then that area might have a slightly higher potential (voltage) than other ares of the grounding plane. This could have some definite effects in sensitive electronic situations and should be considered when designing a new PCB.
  5. Heat/Warping — A major downside to PCBs is the rigidity of the material; worse, when it heats up, it can often warp and become unusable. This could also be a problem in acid etched and wire wrap boards (the warping), but since the connections are often either larger traces or wires, the chances that the warping would break the connection are lower. Worse yet, the example above (dumping current into a ground plane) can create its own heat and warp a board without even being in a heated environment. Thermal budgets become important in any new PCB design and you should be mindful of them. Some SPICE programs even allow you to check out what the heat/power dissipation will be before putting the components on a board.
  6. Low Power — Unfortunately for high power circuit manufacturers, PCBs require extra care when they contain high voltages or high currents. Newer boards are often optimized for power savings, so high power situations are not as much of a priority for the tools that create PCBs. There are often constraints in the layout programs to ensure proper safety requirements, but other steps might be necessary, like separating high power lines from one another so they do not spark or create noise on other lower power lines.

Printed circuit boards allow for reliable products that can quickly be deployed to customers or used in a lab situation to test new circuit configurations. As long as you are mindful of the pitfalls of PCBs listed above, you can create circuit designs that can do just about anything imaginable.  If you have any suggestions on how to create better PCBs or circuits in general, please leave your thoughts 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.

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Categories
Analog Electronics Blogging

New Theme (for real this time)

Hey everyone,

I took the time this Thanksgiving to give my artistic skills a shot (and my pathetic attempts at modifying WordPress templates…PHP and HTML are not my forte). If you happen to read this post and you have any thoughts on my new blog of a picture at the top, I would really appreciate it. I got the idea for the blurry circuit from a great new book I’m reading “Analog Circuits — World Class Designs”, edited by Bob Pease. I’m only just starting the book, but enjoyed the simplified model of slew rate in an op amp and thought it would look cool on the top of the page. If you have any other thoughts or additions you think I should make to the site, please leave them in the comments. Thanks!

~Chris

PS. Looking for a great gift for family and friends for the holidays? Why not subscribe them to this blog? Just enter their email in the form in the upper right hand corner and if they’re actually interested, they can confirm the subscription through the FeedBlitz site. It’s free and mostly this was just an attempt to get more email readers 🙂  If you’re interested for yourself, the RSS feed works too! https://chrisgammell.com/feed (just add the address to your favorite feed reader).

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 Economics Renewable Energy

Renewable Energy Investing

I’ve been writing a lot more lately about renewable energy than I have analog electronics, but I think with good reason. There has been added interest on the part of many because of Barack Obama’s election to the presidency and his promise to invest $15 billion per year for 10 years in order to create 5 million new “green collar” jobs. But where and how do we separate the promises and the politician from the reality? How do we know that renewable energy will help pull America out of our economic recession? And most importantly, once we are confident that this idea of a green economy could work, how do we know where to put our money and invest?

I think the most important thing to point out is that there are going to be a LOT of bad investments out there. My last entry about EEStor is a good example; a company that could potentially be doing great things, but more likely will look for lots of investments and then not deliver on their promises. Like any other engineering activity, renewable energy is an iterative process. On average, the solar technologies in 2 years will be better than the technologies we see today (especially because of the higher interest in renewables and the notion that eventually oil prices will return to extremely high prices). Further, there will be other companies “green washing” (basically talking the talk of being an energy friendly company, but not walking the walk). If you decide to invest in solar, wind, geothermal, etc, you should realize that beyond the usual risk of investing, there are risks associated with unknown, unproven technologies. Prices on renewable companies haven’t gone through the roof yet, but human nature tells us that there will be an overzealous buying of stocks at some point. Let’s look at what we should do when investing so we avoid any unnecessary losses:

  1. Are they forthcoming with details? — Companies like EEStor might try to be secretive because they have a breakthrough technology, but there are limits on how much a company should really withhold information. Mostly it comes down to whether or not you want to roll the dice on a company that keeps you in the dark. I would much rather see a proven technology (heck, a prototype would be nice) and then make my decision based on that. You might not get the 1000% returns that people expect (perhaps they’re nostalgic for the dot com days?), but you will go into an investment with facts you can hold companies to when things get tough.
  2. Do you understand everything about what they are doing? — This is important for two reasons. First, it is important because you should not invest in what you don’t understand. If you don’t get how a solar cell works, don’t get how it could benefit society and are only sure that it will somehow produce power, then it is not a good idea to dive headfirst into investing in that company.  Second, some of the best investing ideas are the simplest ideas; if you cannot explain to someone in 1 sentence what the company does, it is probably too complex to form a productive, sustainable company (a generalization, of course). Examples of this might be Apple (“They sell computers and music players”). Of course the internals of their products are more complex, but the products are simple to describe and sell. If you have a company that is producing a chemical that is required in the fabrication of GeAs solar cells for the 3rd implantation process…yeah, might not be such a great buy at first glance.
  3. Have they brought in good management? — The best ideas in the world are worthless if you can’t sell them. It’s not greedy; it’s business. Sure, the truly great ideas will always rise to the top (eventually), but since we’re talking about investing here, we need to concentrate on ideas that are likely to get to market quickly and ones that will be successful for the long term. Good management will include a proven track record at start ups (there are very specific skill sets) and some experience in the industry. Note that these people can sometimes be the founders, but unless the creators of the new idea or technology have significant soft skills, don’t expect it.
  4. Are they digging for the gold, selling the gold or selling the shovels? — This was always an analogy and investing idea that I liked: the ones who made the most in the California gold rush were not the ones digging the gold, but instead those selling shovels.  To give an example for each, the diggers here would be the solar companies (cell manufacturers), the sellers of the gold would be the energy companies and the sellers of shovels would be fabrication equipment manufacturers. The best case scenario is when you find a great company supplying the shovel with little competition. If the “shovel-maker” can continually sell their product to each new technology that pops up, then they will be well positioned to outperform the rest of the market.
  5. Do they have a simple product that can be produced quickly and efficiently? — Really, I’m thinking about GreenField Solar Corp, which I recently read about in the Cleveland Plain Dealer. They have a simple solar concentrator that can mostly be built from off the shelf components. However, the best part of their implementation is that they would license and franchise the production facilities (making the start-up cost lower for the actual company) and they would only retain sales ownership of their proprietary software, control systems and solar cells (a very specific type). It is reminiscent of the lean manufacturing idea that Solar Automation eschews and Henry Ford pioneered. If you have TONS of money you want to invest, you could always try to start a solar factory.

For my part, I am staying put on renewable energy stocks for now. In reality, it’s always a very difficult climate when you try to guess what technology will come out on top. It happened with the biotech stocks in the early- to mid-2000s, it happened in the dot-com era (post-bust), it happened in the 90s with the PC and chip makers, it happened in the 80s with banks and so on back through time. If you are reading this post, you likely either found my site through searching or you were linked here; in either case, if you are not sure about renewable energy stocks, stick with what you know and continue to monitor the industry. Then when you see a disruptive technology that you think WILL revolutionize the industry, maybe buy a few shares to help support the company. However, do not expect to make money for a few years and continually research your target company. If you are REALLY looking to invest in your favorite solar or wind company, go buy a solar array or turbine and try powering your home. You will help the company and yourself.

If you have any questions about investing in renewables or if you have any favorites you would like to let others know about, please leave them in the comments.