Electronic Design

Bob's Mailbox

BOB'S MAILBOX

Dear Mr. Pease:

I've been reading your articles in Electronic Design since they began and I just wanted to say that I've thoroughly enjoyed them.  Their content is certainly interesting to me, but not nearly as interesting as the thoughts they provoke.  It warms my heart to read the thoughts of someone who seems to believe, as I do, that our best problem-solving instrument is not on the lab bench but right between our ears.  The biggest thing I learned at M.I.T. was not any specific knowledge but rather how to think.  There are plenty of bright people but not enough is done, in my opinion, to teach these gifted people how to leverage their intelligence into setting up and actually solving problems (both everyday problems and professional problems, such as in engineering).

I believe your articles really encourage your readers to use their brains more effectively by showing them your thought processes.  You show how to use what I would call "non-traditional" thinking.

Your article in the April issue was quite funny.  I rapidly surmised the thrust of the column but I was chortling nevertheless.  It reminded me of an April 1st issue of some electronic journal I read a few years ago.  It had an article about fuzzy logic, a concept that was totally unfamiliar to me.  Well, as I got further into the article, I said to myself that fuzzy logic was an amusing subject for what was obviously a spoof.  I was rather chagrined, though, to find at the end of the article that fuzzy logic was quite real.  When I see consumer products like camcorders mention fuzzy logic in advertisements, I feel doubly chagrined.  It's here to stay.  Perhaps my reaction has been a typical one, which explains why fuzzy logic has been so hard to catch on here - everybody laughs at it because it seems to challenge (but really doesn't) some of our basic engineering teachings.  I recall a similar reaction to "sequency" theory the first time I was exposed to it.  As I get older, I am far less quick to make value judgements on new ideas as we obviously have only scratched the surface in explaining and controlling our physical universe.

Your February 6 column that mentioned dead cars was of special interest.  I used to have a 1970 Saab 99E, which became a part of the case files of the Attorney General's Office and the Federal Trade Commission.  It was the ultimate lemon (until I saw the repair records for a friend's Ford Tempo).  One relative called my car the "slob" instead of "Saab."  After I was able to extricate myself from my Saab folly, I became interested in how many Saabs were disabled alongside the road.  I was curious as to whether Saab had improved their quality since my car was built.  I didn't actually count Saabs, but I sure saw a lot of them with their emergency flashers on and their hoods up!  I think I saw more than you would expect from their market share in New England, but possibly that is simply wish fulfillment.

You are truly a credit to our alma mater.  If you're ever in the New England area in January for a week, you should consider giving some sort of Independent Activities Period course at M.I.T.  I think the students and M.I.T.  community would love hearing you for an hour or two a day for a few days or a week!

Robert A. Piankian, (another RAP!), Consultant, Brighton, Mass.

Yeah, I've thought about writing "What's All This Fuzzy Logic Stuff, Anyhow?," but nothing I could write would be as funny or weird as what I read in technical journals.-RAP

Dear Sir:

The proposal of Mr. Doug Raymond about finding "hot spots" with a mercury-filled fever thermometer (April 16 issue) is an interesting and working approach.  BUT spilled mercury from a broken thermometer nicely distributed through the interiors of an electronic assembly might move more than an eyebrow from a quality or security inspector!

The rough facts:  Mercury is a conductor and its vapor deposits are also conductive.  Also, it slowly vaporizes and vapors are poisonous.

However, we spend fortunes to market our temperature recording labels in the U.S.A. and other countries worldwide, and here comes Doug Raymond who hits my head with his proposal...

Does anybody these days read small ads anymore?  Companies with smaller budgets and smaller ads get lost and the readers might miss interesting products and technologies.

Readers:  Small ads may also carry very useful contents.

Dipl. Ing. Ernest Spirig, Rapperswil, Switzerland

You are quite correct; mercury thermometers are kind of dangerous, and I should have said that.  But fever thermometers filled with red alcohol are safe enough.  The little temp-sensing dots sold by Spirig are, of course, even smaller and faster.  And they are good for wider ranges - but with less resolution.-RAP

Dear Bob:

Your recent "Vice-Versa" column plus a prior column on having people accountable for their work reminded me of an incident when we were leasing hangar space from an aerial photography company near Dallas.  Whenever their aircraft were serviced, the owner made the service mechanic ride along on the first checkout flight.  During service to a helicopter, the tail rotor pitch cables were reversed.  The tail rotor is an antirotation mechanism, with the pitch (angle) of the blades determining the amount of thrust to counteract the natural tendency of the helicopter body to rotate with the main rotor.  As they lifted a few inches off the pad, the body began to rotate.  The pilot applied what he thought was thrust to counteract it, and as I'm sure you realize, the rotation just sped up.  The pilot was quick-witted.  He put the main rotor back to neutral pitch and the helicopter smacked down onto the pad, bending a landing strut.  But there was no other injury, other than to his pride.  I also recall the animated discussions with FAA inspectors over whether this was a flying or taxiing accident and the effect this would have on their insurance premiums.  Sorry, I don't know how that was resolved.

Marvin T. Anderl, Richmond, Va.

Wow, what a sharp pilot!  I like that the mechanic gets to go along on the test flight!-RAP

Hello Bob:

I've enjoyed your articles on feedback and polarities.  There is a common machine in which the polarities switch depending on the situation.  Operating the typical, three clutch "caterpillar" tractor uphill, one releases the clutch on the side of the direction to be turned.  However, going downhill, with gravity and the load pushing the tractor, one releases the clutch opposite the turning direction.  On hilly terrain with many obstacles, it is not at all intuitive.

Thomas Lakia, Coastal Designs, Los Gatos, Calif.

Hey, that's a real vice-versa switch, enough to make George Philbrick nervous!-RAP

Dear Bob:

Your column on vice-versa stuff reminded me of a friend who used to win drinks with motorcycle and bicycle riders by betting them that when they pressed their right thumb on the right handlebar, a right turn would be initiated.  Of course, you had to let the thumb go down and then come back toward you to keep from falling over!

That front wheel is a classic gyroscope.  Turning the handlebar left causes precession to tip the wheel, and the bike to which it's attached, toward the right, thus initiating a right turn.  It's not initiated by leaning to the right as most believe, because you unconsciously push the handlebar first.  Try this when there is room to spare and you are moving at least fast enough to keep your balance without effort.

Lee Seelig, Senior Staff Engineer, TRW LSI Products Inc., La Jolla, Calif.

Come to think of it, to make a bike LEAN left, you first STEER right.  To make it STOP leaning to the left, you steer MORE to the left.  Maybe that's why it's hard for kids to learn.-RAP

 

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