Electronic Design


Where Networks Are And Will Be
In reply to your July 10 article regarding MP3 files and slow networks \["If Music Cravings Topple Networks, What Will Video Do?" p. 60\], the ban on software file-sharing applications like Napster won't solve any problems. Look at the millions of people who already use it. With so many users, they can resort to e-mailing these files to one another if necessary. Chat rooms still exist. If Napster goes down, people will find other ways to trade MP3 files. Let's face it—what's done is done, and it can't be stopped now without expensive changes to every ISP in the country. And who will pay for that new hardware and software?
Greg DeCelle

Yes, networks can be brought to their knees by multiple, huge high-bandwidth transfers. Perhaps the solution is to stop "giving away" bandwidth. Two quantities could be measured: volume and speed. Organizations could permit a certain volume/speed product for "free" and charge above the excess. This would allow people who still wish to transfer DVDs between themselves to do so while paying their fair share. At the same time, those who don't significantly load the system could still have access "freely"/cheaply.
John Elder
Senior Engineer
Geospace Research Inc.

They'll Do It Only Because They Can
My response regarding the climate-sensing vending machines is yes, it strikes me as a new low in marketing, but it's probably inevitable \["Just Because We Can Do Something, Should We?" July 24, p. 48\]. But when you spy one of those infernal machines at your corner store, get a spray can of coolant. Perhaps if the vending machine detects, say −20°F, it might dispense a soda for five cents. Then, call all of the neighbors to share in your good fortune.

Yet you asked, "should we?" Back in the '50s when I was working at a research foundation, some vending company inquired if we couldn't design a machine to dispense hot meals. We replied that there was one "simple" solution. That is, if the meals were maintained at an elevated temperature (I forget, but I think it may have been >140°F), the food wouldn't spoil—but it would have no nutritional value after, say, 24 hours. The marketers of that vending firm were enthusiastic and asked that we immediately begin designing such a machine. Our management refused! They wouldn't be a party to such deception. That was 1957. Seems marketers haven't changed. Have engineers?
Ed Oxner
Technical Support for Analog Switches & Multiplexers

I'm a product design engineer (specifically electronics). I'm equally skeptical of some of the directions that I see our innovations and abilities taking us. There's talk of refrigerators that will categorize what kind of groceries we buy and feed the information into national databases to help steer the market via the Internet. We have been talking about Internet-ready appliances and I personally don't like it. I think it will be an interesting challenge to bring it to fruition, but then again I wouldn't want one in my home. I don't like the idea of my every move being scrutinized by my appliances and the world market being adjusted accordingly. How many gallons of milk I purchase annually is none of my refrigerator's business.
Name withheld by request

Your moral compass is dead on, but I fear your grasp on reality is somewhat loose. Let's face it, money talks. Just because one engineer refuses to design a socially irresponsible product (and could quite possibly lose his or her job for it) doesn't mean that all engineers will refuse. History has shown us that if the money is there, someone will pursue it. Which takes the higher priority: feed the mouths that you are responsible for, or stand by a moral code and watch the product be developed by someone else anyway? I commend your thoughts, but until greed and avarice are purged from the human spirit, you are dreaming the impossible dream.

You have sown the seeds of an extensive psychological dialogue with your comments, but to what end?
Michael A. Ference
Senior Product Engineer
DC Products

Intellectual Fire Is What Matters
I don't care where one got his or her education, a degree is meaningless unless one has ability, talent, and a desire to excel \["A Contrasting View On Universities," July 10, p. 70\]. We often forget that education is far more than taking classes and passing tests. I have worked with American engineers educated at one of the less-esteemed institutions who were brilliant, and I have worked with American engineers from many of the prestigious schools who were duds. The same can be said about those engineers educated in foreign countries. If an individual lacks the basic intellectual fire, education doesn't matter.

As for PhDs, for the level of effort needed, most Americans would rather exert themselves in more lucrative directions. Also, to maintain their PhD programs and research budgets, universities actively recruit anyone they can to fill the roster. Admittedly they recruit the best that they can. Wouldn't you? Finally, no one cruises to a PhD. It requires work and determination. It's disingenuous to state otherwise.
Jesse D. Sheinwald
Senior RF Engineer
Telular Corp.

Ode To The Toilet
After reading your napkin saga, "Ode To The Paper Napkin—The Untold Story" \[August 7, p. 54\], I had to write to tell you about our toilet. Now, I'm the senior (old at 50) electronics engineer at the company. Whenever we have a particularly difficult problem to solve, my fellow engineers tell me to go to the bathroom.

For some unaccountable reason, our incredibly drab men's room or perhaps the change of "attitude" gets my creative juices flowing, and I invariably come out with a new avenue of attack, which more often than not is fruitful.

It has gone way past the point of a joke because of the high caliber of ideas I actually come up with in the bathroom. There are almost as many bathrooms in the world as there are napkins, so maybe I have discovered another solution to engineers' problems. It takes a strong constitution or a weak bladder, however, to spend that much time "on the can."
Alan Cross-Hansen
Senior Design Engineer
E-Z-EM Inc.

Is That E-Mail Really Anonymous?
Many of the "anonymous" e-mail services that are available aren't truly anonymous \["Whistle Blowing: Should I? And How To Do It Safely," August 7, p. 150\]. The IP address of the sender is usually included with any e-mail sent. This is true for Hotmail, Yahoo, Beer.com, and others. Many times, e-mail programs aren't set up to display this header information, but it's available with just a few clicks of the mouse. Many programs will help you trace an IP address unless it's hidden behind a firewall.
Don Hediger

There appear to be two errors in the Idea For Design "Differential Receiver/Driver Overcomes Noisy Grounds" \[July 10, p. 138\].

  1. The two reduced equations, VO = 6V1 and VO = VR, should be:

    VO = VS, and VO = 6VR using the values provided for R1 through R4;

  2. Neither of the published equations, nor my suggested corrected ones, provide the claimed result of noise cancellation.

The circuit appears to be a novel and very useful application of the noninverting adder circuit. See for example: "Applications Manual for Operational Amplifiers—A Library of Feedback Circuits," Philbrick/Nexus Research, Second Edition, 1966.

But I believe the very desirable result of noise cancellation can only be achieved if two conditions are met:

  1. All four resistors must have the same value;
  2. The output impedance of the line driver must be much less than the value used for these equal resistors. I believe this is the case for the line driver circuit provided.

Peter Cone

There's a mistake in the schematic diagram. The labels for R3 and R4 are swapped. Swapping R3 and R4 makes the simplified equations VO = 6V1 and VO = VR correct. I believe this provides the noise cancellation and also allows the gain to be set to any value.
Dinal Anderson
Georgia Tech Research
Institute, Atlanta, GA

An Old Idea That Didn't Catch On
You're right—I never saw many Compactrons in old equipment \["40 Years Ago," July 24, p. 58\]. They shared an early demise with the RCA Nuvistors due to the transistor becoming widespread.

Interestingly, the idea of combining more than one tube element for a complete application within the bulb wasn't new. Loewe, a German radio manufacturer and tube pioneer, even invented a form of "integrated circuit" in the late 1930s! They not only combined two or three tube systems in one glass envelope, but also incorporated some resistors and capacitors to form the basic design of a tube radio. The components were standard but were sealed within the glass envelope and mounted in the bulb.

This idea didn't really break through, as such an "IC" was very expensive and replacing it would lead to excessively high servicing costs. So, Loewe only built some types of radios and eventually stopped manufacturing the tubes.
Stefan Graef
GEntwicklung-Motec GmbH
Hadamar, Germany

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.