Electronic Design

Bob's Mailbox

HELLO BOB, A note concerning electric cars and plugin hybrids: Consider that politics has little to do with engineering and/or science. It only pays lip service at those altars. So, somebody has to do serious planning for the immediate future.

I’ve been working on some serious battery-charger designs. One of our planners (an engineer) did some research in good old California. We learned that your utility companies have problems with metering even small numbers of plug-ins, nor can the California infrastructure absorb many cells of even 5000 plug-ins. You’re running at about 81% capacity, and without a smart meter and control, we would easily overload the electricity capacity on two peaks every day. That’s not politics. It’s business.

American, Japanese, and European manufacturers were contacted, and none of us can really do this without the cooperation of the utilities. Oh sure, we can sell a few and look green. The press wouldn’t even know who to blame when the grid broke. Some of our competitors have been doing that, but without that smart meter, it’s the wrong thing to do. They know it. But that’s business.

All of the automakers easily agreed on the meter and protocol. The utilities did not. They already have contracts on meters that aren’t smart. That’s business. The real greenies were there, too. They’re part of politics. They want California to be energy neutral in 10 years—sorry, no data on how to do it. Industry must be hiding it.

Back in the Midwest, we run about 1/2 the total power per person aggregate (at 740 W per person continuous) than you do out west, but that’s because of our low transport and air conditioning costs. Perhaps just targeting our levels would be a better starting point. There is no magic bullet in the next 10 years. So the utilities answer to the greenies and business, not to the engineers. Our charger is going to be great. We will get patents. It will be used all over, but not in volume in the west.

–AN ANONYMOUS ENGINEER

HELLO, ANONYMOUS: I’ve always been suspicious of the “visionaries” who think it is going to be so great to have lots of electric cars, plug-in hybrids, and hydrogen-powered cars. Who is going to build the electrical generating and power-transmission capacity for recharging a lot of cars? Who is going to make the hydrogen fueling stations and the hydrogen generators?

Not the same people who are smoking bad stuff and dreaming improbable dreams. Thanks for reminding us. Right now, the only thing saving us from these problems is the high cost and limited availability of such cars. If we got more such cars, we would not be able to drive them to work the next day after a little heat wave.

–RAP

DEAR MR. PEASE, I’ve often used components in various packages: TO-92, TO-220, and so on. Usually, these components are pulled off the shelf without any thought to the package they are in apart from obvious questions such as “Will the package handle the power to be dissipated?” (Oh, I disagree! We engineers usually pick a part in a (compact) package that makes some sense for the task at hand. We don’t pick a 20-W package to do a 28-mW job, nor vice versa. And if I ever tried to do that, when I was a kid engineer, my boss would have chewed me out. So we all have to learn somewhere. I mean, who ever went to school to learn about heatsinking? /rap) I’ve been wondering, though, what the history of these packages is. (It is obvious that each package is a compromise of all those terms, so TO-92 (and its variant packages) will dissipate almost a watt—just before the thing dies! /rap) Who designed each one? (Probably 34 different JEDEC committees... /rap) Why did they choose the particular shape it is? (Surely, because the guys who said they could make it argued that it was a feasible package to make in high volumes profitably... with good results for the users. /rap) What were the tradeoffs that had to be made during development? When did it first get used and why? (I wasn’t there. How the hell would I know? /rap) There seems to be absolutely no information on such things. I’m sure an awful lot of R&D went into those packages, but it just seems to have disappeared, leaving only the application information (such as package drawings) behind.

–JOHN DALTON

HI, JOHN: On the contrary. The history has dried up, but the facts remain. These packages remain as examples of packages that have been, some of them, very popular—in the dozens of billions! Which other packages have you considered? The TO-2, TO-4, TO-6? TO-91? TO-93? Who the hell ever heard of them? Nobody! And guess why? I doubt if there are many survivors of that era who would like to talk about their struggles with these packages, are there? But all of the packages that survived were subject to the realm of feasibility.

-RAP

Comments invited! [email protected] —or:
Mail Stop D2597A, National Semiconductor
P.O. Box 58090, Santa Clara, CA 95052-8090

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