MightyOhm

I recently picked up a copy of Tim Williams’ Circuit Designer’s Companion after I noticed it on my Amazon recommendations list (which seems to know my tastes a little too well these days.)

This is a fun and useful book.  The emphasis is on practical information that is useful to working engineers, not PhD students.   This means that there are a lot fewer equations in this book than The Art of Electronics and it’s a lot less intimidating for someone without a degree in Electrical Engineering.  The book’s roughly 400 pages include topics such grounding and shielding sensitive circuits, some basic tips for routing PCBs, why it’s usually better to buy a switching power supply than build your own, some comparisons of batteries, and how to pick a fuse.  (Sadly, the latest microcontrollers and Lithium battery technologies are missing – not surprising, since the 2nd edition was released in 2005.  Time for an update?)

I like Williams’ writing style, and usually pick this book up first to see if he has a quick solution to the problem at hand before diving into one of my more dense engineering texts.  While this book isn’t a replacement for my other (heavier) reference books, it’s a welcome addition to my desk.  I keep it within easy reach.

I am pleased to announce that the MightyOhm Wiki is now online and open to the public.

While there isn’t a ton of content yet, my hope is that the wiki will become a useful means to share information and resources relevant to the site.  At the moment, there are pages for electronics vendors, hardware/software tools, and PCB manufacturers.

Another page I have been working on for a while is the surplus directory, which lists surplus electronics stores around the country.  If you have a favorite surplus goldmine in your area, please create an account and add it to the wiki!

MightyOhm Has a Wiki.  Check it out.

I recently saw David Agans’ book Debugging mentioned in one of the many trade journals I receive (I can’t remember which one).  After seeing how much praise it received on amazon.com, I decided to pick up a copy.

Debugging really spoke to me because a large portion of my career has been devoted to finding and fixing hardware bugs.  I finished it in just two or three evenings (it’s a quick, fun and engaging read).  The examples are particularly interesting and relevant to me because many involve issues with embedded systems.  Admittedly, perhaps most fascinating is the one about a living room lamp that turned on anytime the author vacuumed the room.

I highly recommend this book to anyone who regularly  troubleshoots issues with any kind of system, software or hardware, mechanical or electrical.  This includes engineers of all discplines, circuit designers, computer programmers, helpdesk operators, web developers, auto mechanics, etc.

David’s nine rules of debugging are (with my notes):

1. Understand the system – Knowing how your circuit, code, or widget is supposed to work will help you fix it.  Read the manual!
2. Make it fail – Knowing how to reproduce the failure is critical to being able to fix it.  Also, stimulate the failure, don’t simulate it.
3. Quit thinking and look – Don’t jump to conclusions and just fix what you think might be the problem.  This wastes time when you inevitably guess wrong.  Keep an open mind as to what the failure mechanisms could be.
4. Divide and conquer -Eliminate what is definitely not part of the problem and focus on what’s left.
5. Change one thing at a time – If you change ten things at once, how will you know which one actually solved the problem?
6. Keep an audit trail – Being able to reproduce the fix is crucial.  Even if you don’t fix the problem, you might discover a pattern or something you overlooked by looking at your notes.
7. Check the plug – When all else fails, check the obvious stuff that you probably should have looked at first.
8. Get a fresh view – Someone else may have more experience with the problem than you do or might see the one thing you’re missing.
9. If you didn’t fix it, it ain’t fixed. -  Don’t stop when the problem just disappears.  It will surely come back later at the most inconvenient time possible.  We’ve all been bitten by this one before.  Never again!

There’s even a free poster available on the book’s website to help you remember these rules during your next debugging crisis.

If you live in the San Francisco Bay Area and are interested in getting your amateur radio license, there are a couple testing sessions coming up in 2010 that may be of interest:

The Bay Area Educational Amateur Radio Society (BAERS) is hosting a Ham Cram on Saturday, January 9th from 8AM-5PM at St. Mary’s Cathedral in San Francisco.  The cost is $30 including the VEC fee.

A “Ham Cram” is a one day workshop where you can get your ham radio license (usually the Technician level) without studying in advance.  I’m not sure I completely agree with their methods of blind memorization over actually understanding the rules, but apparently this method works and most people pass on their first attempt.  If you’re short on time and want to get your license in a hurry, this is one option.

Thanks to Robert for the heads-up on the January session.

AERO is another SF-based group that regularly posts flyers advertising their own ham cram sessions.  Their most recent poster is outdated, but the site mentions there will likely be an upcoming session in February 2010.  I just took the General license exam at their November session and was really impressed by how many people were there and how professionally run the event was.

Update: Their next session is on February 7th, 2010 at 8:45AM.  Details here.

Studying the old fashioned way:

If you don’t like the “cram” method, you can always pick up a study guide (Technician, General, Extra Class) and spend a few weeks studying for the test like I did for both my Technician and General license exams.  There are even a couple online practice tests to help you study.  When you feel comfortable with the material, you can take the exam at the sessions above for a $14 VEC fee without doing the cram.  I know AERO allows this, but it would probably be a good idea to check and make sure BAERS permits this as well.  In either case, I recommend that you RSVP to ensure you get a seat and get notification about changes to the venue, etc.  Contact info for each group is on their respective websites.

Good luck and 73 from KF6PBP!

Yesterday I drove down to Linear Technology in Milpitas for a free LTspice IV Seminar, hosted by electronics distributor Nu Horizons.

The seminar was led by LTspice author and advocate Mike Engelhardt.  For someone like me who has never used LTspice before but wanted to see what all the fuss was about, the seminar was an extremely informative introduction to what appears to be a very powerful and well-supported design tool based on Berkeley SPICE.  Mike claims that in most cases, LTspice is the fastest SPICE simulator around, making it the industry leader both in price (it’s free) and performance.

The best part?

After the seminar, Michael Payne of Nu Horizons sent out a link to the class slides and example files as well as a list of useful LTSpice Keyboard Shortcuts.  So even if you missed the class (or the tour didn’t include your part of the world), you can still learn about the circuit simulation tool that has been making waves in the open source hardware community.