Category Archives: Design Master Expert Assistant

3rd Qtr 2011

(c) 2011 Design/Analysis Consultants, Inc.
Newsletter content may be copied in whole or part if attribution
to DACI and any referenced source is prominently displayed with the copied material

This Issue: NEWS BITE: Mutant Singing Cantaloup Wins Karaoke Contest! / MORE UNINTENDED CONSEQUENCES: Hands-Free Faucets / DESIGN MASTER TIP: AC Rectifier Worst Case Analysis Made Easy / ART MEETS ENGINEERING: The Invisible Man / STATISTICAL DESIGN PITFALLS: Monte Carlo Is Not Worst Case Analysis

NEWS BITE: Mutant Singing Cantaloup Wins Karaoke Contest!

Freaky Robot Mouth Learns to Sing,”
Evan Ackerman, 13 July 2011, IEEE Spectrum

MORE UNINTENDED CONSEQUENCES: Hands-Free Faucets Harbor More Germs Than Standard Faucets

Details here.

DESIGN MASTER TIP: AC Rectifier Circuit Worst Case Analysis Made Easy

In our previous Newsletter we provided a pretty good estimate for the ripple current for the bulk capacitor in an AC rectifier circuit. But what if you have a large volume product and you need a full worst case analysis to ensure high reliability, but one that is not overly pessimistic so that you can minimize cost? Design Master can help you achieve that optimum balance.

As readers are aware, we’ve started to release some DMeXpert “fill in the blank” WCA templates to make the design engineer’s life a bit easier. One of these is our AC Bridge Rectifier Analysis (ACBR1 $19) which allows the designer to determine all of the worst case component stresses within a minute or two. The analysis includes the effects of source impedance Rs (such as transformer secondary winding ohms), which if present can be used to reduce capacitor ripple current requirements, hence reduce capacitor cost.

As those who have studied AC rectifier circuits are aware, this seemingly simple circuit has resisted for decades all of the attempts to generate a single-formula solution, until recently, which we’ve included in ACBR1. Based on Keng Wu’s article, “Analyzing Full-Wave Rectifiers With Capacitor Filters” (1 Jan 2010, Power Electronics Technology), Wu’s formula allows a straightforward circuit solution, greatly reducing computational time. So with ACBR1 you can just fill in the blanks, click Calculate, and let Design Master do the rest.

ART MEETS ENGINEERING: The Invisible Man

Engineers who work for the military are sometimes required to design clothing, equipment, or even entire shelters to be “invisible” to various detection means. Chinese artist Liu Bolin has a gift for applying such camouflage in a non-technological way, as seen below. Hint: If you can’t spot Liu, look for his shoes first.

From “The Invisible Man: Dragon Series,” Vurdlak, 28 June 2011, http://www.moillusions.com

Some more fascinating photos here and here.

STATISTICAL DESIGN PITFALLS: Monte Carlo Is Not Worst Case Analysis

A lot of folks like to let a simulator crank out “worst case” results, using Monte Carlo statistical methods. But as we’ve explained previously (“Design Master vs Extreme Value, RSS, Monte Carlo, & Simulation,” and “Design Master vs Monte Carlo“), this can be not only time consuming, but risky. For example, Monte Carlo can easily miss small but significant errors (see example below). In addition, if the Monte Carlo runs are improperly implemented (such as including temperature or other dynamic variables) you will likely obtain wildly inaccurate results.

The Design Master Advantage

Instead of statistical sampling, Design Master uses a top-down approach to achieve safer and more cost-effective results, by (a) detecting the extreme limits of performance, and then (b) using a proprietary probability algorithm to estimate how often those results will exceed the specification limits.

EXAMPLE

Design Master results at 2 samples/variable versus
Monte Carlo at 10,000 samples/variable, for the gain of an 8-variable filter

As can be seen, the Monte Carlo analysis detected a minimum of 8.42 versus the actual minimum of 7.86, a 7% error, and a maximum of 16.0 versus the actual maximum of 18.8, a 15% error.

Metal Oxide Varistor (MOV) DMX Analysis File Released

Metal Oxide Varistor (MOV) DMX Worst Case Analysis File
MOV1 $12.50

(DMX files are available free to Design Master™ Professional Edition users who purchased or upgraded DM not more than one year prior to the DMX file release date.)

The MOV analysis determines whether a Metal Oxide Varistor transient voltage suppressor will (a) survive a specified surge voltage or current, (b) clamp the surge below a specified voltage limit, (c) not clamp the normal operating voltage, and (d) survive a specified number of surges. MOVS are typically rated with 8x20us current waveforms, and (just to be confusing) 10x1000us energy waveforms. MOVs also have a lifetime (number of allowable surges) that depends on peak current, pulse width, and temperature. To complicate things further, MOV clamping voltages are a nonlinear function of surge current. To help make the design engineer’s job a little easier, this analysis contains adjustment formulas for all of these factors. Also provides standard surge waveform requirements and helpful hints.

DMeXpert™ (DMX) files guide the user with pop-up instructions, component selection lists, standard part values, important formulas, and a variety of other tips that are activated when entering a Formula cell. It’s like having a design/analysis expert at your side.

Transient Voltage Suppressor (TVS) DMX Analysis File Released

Transient Voltage Suppressor (TVS) with Optional Steering Diode DMX Worst Case Analysis File
TVS1 $12.50
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(DMX files are available free to Design Master™ Professional Edition users who purchased or upgraded DM not more than one year prior to the DMX file release date.)

The Transient Voltage Suppressor analysis determines whether a TVS avalanche diode and optional steering diode will (a) survive a specified surge voltage or current, (b) clamp the surge below a specified voltage limit, and (c) not clamp the normal operating voltage. Good for any TVS diode and steering diode; just fill in the blanks using data sheet values, and get an answer in a few seconds. TVS diodes are typically rated with 10x1000us current waveforms. Steering diodes are typically rated with line frequency half-sine current waveforms. When the applied surge has a different waveform, however, the TVS and steering diode ratings must be adjusted accordingly. In addition, the ratings must also be adjusted for pulse width and temperature. To help make the design engineer’s job a little easier, this analysis contains adjustment formulas for all of these factors. Also provides standard surge waveform requirements and helpful hints.

DMeXpert™ (DMX) files guide the user with pop-up instructions, component selection lists, standard part values, important formulas, and a variety of other tips that are activated when entering a Formula cell. It’s like having a design/analysis expert at your side.

AC Full Wave Bridge Rectifier DMX Analysis File Released

AC Bridge Rectifier DMX Worst Case Analysis File
ACBR1 $19

(DMX files are available free to Design Master™ Professional Edition users who purchased or upgraded DM not more than one year prior to the DMX file release date.)

This updated and easy-to-use analysis provides all of the key waveforms, voltages, and currents for the AC full wave bridge rectifier circuit, including the effects of source ohms. Output includes average input amps, rms input amps, input watts, Rs watts, capacitor rms amps, average load volts, average load amps, and output watts.

Capacitor Current

DMeXpert™ (DMX) files guide the user with pop-up instructions, component selection lists, standard part values, important formulas, and a variety of other tips that are activated when entering a Formula cell. It’s like having a design/analysis expert at your side.

1st Qtr 2011

(c) 2011 Design/Analysis Consultants, Inc.
Newsletter content may be copied in whole or part if attribution
to DACI and any referenced source is prominently displayed with the copied material

This Issue: NEWS BITE: Astronomer Discovers Giant Eye Staring At Earth! / DESIGN MASTER: New Pricing Structure / COMPONENTS: The Most Popular Op Amps? It’s A Secret! / CONCEPTUAL DESIGN: Look At The Big Picture / COOKING & MEASUREMENTS: Why Engineers Get It Right

NEWS BITE: Astronomer Discovers Giant Eye Staring At Earth!


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The Helix Nebula, “Hubble’s Best Photos” by Lauren Effron, Discovery News

DESIGN MASTER: New Introductory Pricing Structure

Effective for 2011, we’re changing our introductory price structure for DM to a flat fee of $85/copy, single user ($25 for upgrades), and providing modeling packages in DMX template format at an added charge. DMX is a DM feature that allows expertly-designed “fill in the blanks” templates to be used for thorough and efficient worst case analysis. Click here for details.

With the introductory pricing structure, DM will only be supported via email, and only with regard to DM operation, not circuit or part modeling.  For those who may need help with modeling, please see DM V8’s expanded help content, and refer to the available DMX templates. If more extensive assistance is required, please contact us with regard to a DM training seminar, or for the provision of custom circuit or part models.

Offer expires 30 April 2011.

COMPONENTS: The Most Popular Op Amps? It’s A Secret!

We were looking for some guidance in building up op amp models for our DMX templates, so we asked several major semiconductor vendors this question: “What are your most popular op amps?” Surprisingly, although the technical contacts said they would like to provide the data, they couldn’t; their sales departments considered the data proprietary, due to competition concerns.

Therefore it seems our alternative is to create our own “favorite” lists. If you have some preferred op amp (or other analog IC) part numbers that you would like to share with the DM design community, please send them in. We’ll post them in future issues of this newsletter. The data will also provide guidance for our development of part models.

CONCEPTUAL DESIGN: Look At The Big Picture

In the 12 December 2010 issue of Electronic Design, Louis E. Frenzel discusses some modern versions of the ubiquitous 555 timer IC (“And You Thought The 555 Timer Was Dead?“).

In that article, Mr. Frenzel also refers back to an earlier article of his , in which he asks, in essence: why in the world does the 555 timer still exist? (“The 555: Best IC Ever Or Obsolete Anachronism?“, 12 Dec 2007, Electronic Design).

Might we suggest an answer? The 555 provides a simple common function in an elegant low-cost manner. This does not mean it is always the best solution (Mr. Frenzel mentions some alternatives), but it certainly is an attractive option, particularly for circuits that don’t contain a uP.

I suspect that Mr. Frenzel was deliberately being provocative to stimulate conversation, particularly with his implication that all modern products contain a uP. If that were true, then yes, why add a part when the uP can provide the timing capability for free? But a huge number of products do not contain uPs, because they simply don’t need uPs.  In fact, avoiding a uP has additional advantages in addition to cost avoidance, including better reliability (by keeping things simple), and by eliminating radiated emissions noise. We have saved some of our customers a lot of money by showing how a dirt-cheap non-uP circuit can achieve the functions they need, while also avoiding the noise issues that would require EMC compliance certification.

Mr. Frenzel quotes from a 1997 article, “…the 555 is dated mainly because it is no longer compatible with the mostly low-voltage (less than 5 V) circuits in use today. Furthermore, it consumes excessive power compared to today’s circuits.”  But this ignores the fact that the 555 has been continuously reincarnated over the years with better performance, operating at lower voltages and current, and available in various modern packages.

From a broader perspective, we think it’s important to stand back and look at the big picture during the concept design phase. We shouldn’t just indulge our prejudices, and grab the parts and designs we’re familiar with. Rather, we should ask: what’s the optimum design? Among other considerations, this means we need to challenge our assumption that newer means better. Maybe, maybe not. There are lots of situations where older-technology designs are much better for certain applications — all things considered — than their modern counterparts. A few examples:

  • 4000 series CMOS: these senior ICs are great solutions for low cost, low speed, noisy industrial applications.
  • Mechanical relays: ancient, but like the 555, continuously modernized, and still the best solutions for numerous higher power industrial designs.
  • Older IC technologies in general: lower cost, less EMC issues, and less susceptibility to electromigration, which is becoming a significant concern with modern minimal-geometry ICs.

COOKING & MEASUREMENTS: Why Engineers Get It Right

“Cooking is awesome because it’s applied science. Biology, chemistry, physics, they all come into play when you’re cooking. I don’t know that I necessarily do anything specialized. I know that some of my more particular habits come out when I’m cooking. I very rarely cook meat, for instance, without a thermometer. I know there are these old-school cooks who would turn their noses up at me because they can tell by giving their roast a touch or by poking it in the right spot and seeing what color the juices are, they can tell when it’s ready to come out of the oven. Well, I can tell when it’s ready to come out of the oven when it’s the right temperature and that is okay with me. You know, my bread—before I invested in a thermometer, sometimes it was too dry and sometimes it was gummy in the middle, but now it’s right every time. I use a kitchen scale for almost everything. If you think about a cup of flour: If I measure the cup of flour it may weigh 4 ounces; if you measure your cup of flour, it may weigh 5 ounces, because the flour is compressible. So you achieve a degree of precision when you measure things that way. Nothing drives me crazier than when you look at a recipe and they call for 1 large onion. I’m guessing that one large onion in Texas is massively different that one large onion in southeast Missouri. You know I can get an onion from the store here that weighs almost a pound. I have no idea if that’s what they meant. So my life got substantially more precise when I was able to start making notes, you know—this much onion worked, this much onion didn’t.”
April Woods, as quoted in “Geeks Cooking: April Woods, the Hungry Engineer,” an interview by Susan Hassler in IEEE Spectrum

 

4th Qtr 2010

(C) 2010 Design/Analysis Consultants, Inc.
Newsletter content may be copied in whole or part if attribution
to DACI and any referenced source is prominently displayed with the copied material

This Issue: NEWS BITE: Reporters Scramble To Adapt To Cameramen Layoffs During Economic Downturn! / DM V8 And DMX Released / REVIEW: The Social Network: Entertaining But Not True / NEWS BULLETS: Unintended Consequences (Reusable Grocery Bags) / RECREATION: Having Fun With Fantasy Football

NEWS BITE: Reporters Scramble To Adapt To Cameramen Layoffs During Economic Downturn!


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Teleactor Annamarie Ho. Photo: Bart Nagel
Q&A: Ken Goldberg Discusses Telerobots, Androids, and Heidegger,” by Erico Guizzo, IEEE Spectrum, 1 Oct 2010

DESIGN MASTER: DM V8 with DMeXpert™ (DMX) Released

DMX provides expertly-designed “fill in the blanks” templates for thorough and efficient worst case analysis. Click here for details. If you purchased Design Master on or after October 4 2009, you can obtain an update at no charge; please contact us for download instructions (new install required for V8).

REVIEW: The Social Network: Entertaining But Not True
“Mark Zuckerberg, Facebook’s young and intrepid creator, is portrayed as a geek who starts his path to dot com glory after getting dumped by a girl … If it were true it would be a lot more compelling.  Back in 2005 and 2006, shortly after the film is set, I interviewed Zuckerberg on several occasions, and he wasn’t much like the guy on-screen.  In addition to actually having a girlfriend, a fact left conveniently out of the film, he had a lot of thoughtful things to say about the world he was creating online. ”
The Social Network’s Science Fiction,” by David Kushner, IEEE Spectrum, 7 Oct 2010

The Bozo Award is presented to screenwriter Aaron Sorkin and the movie’s producers for their lack of integrity, as demonstrated by their willingness to damage reputations through false representations of actual events.

NEWS BULLETS: Unintended Consequences Strike Again

“The CALL7 Investigators tested several reusable bags used by 7NEWS colleagues and another from a woman going into a Denver grocery store. Marchetta took the lab results to Dr. Michelle Barron, the infectious disease expert at the University of Colorado Hospital. ‘Wow. Wow. That is pretty impressive,’ said Barron. Barron examines lab results for a living. ‘Oh my goodness! This is definitely the highest count,’ Barron commented while looking at the bacteria count numbers.”
-“Reusable Grocery Bags Breed Bacteria” By Theresa Marchetta, 28 Sep 2010 Denver News

RECREATION: Having Fun with Statistics and Fantasy Football
Design Master™ is used by engineers to help create highly reliable products, but it has been suggested to us that it can be used for some fun, too, such as fantasy football or other games that use statistics. It might even provide a bit of an edge, because its probability models provide more information than simple statistical averages.

For example, you can define a group of players in the Variables Library, enter the raw stats for each player, and let Design Master generate their “player strength” probability models (Tools/Make A Model From Raw Data).

In the worksheet, you create a simple Team formula that defines the strength of the team, using a weighted sum of all the players —

TeamA = 0.2*Player1 + 0.10*Player2 + 0.15*Player3 + …

— where the weights add to 1.0 (100%).

Then press Calculate to generate the team’s probability model.

Repeat this for a competing TeamB and its players, and then compare the team models:

 

 

TeamA strength = 5 to 10                                                TeamB strength = 4 to 16

There are many ways to make a  comparison, but a simple way would be just to subtract the teams. For example, to determine the probability of TeamA losing to TeamB,

TeamAWin = TeamA – TeamB

where the minimum limit is set to zero (i.e. the case where TeamA is less strong than TeamB).

Probability models help guard against counter-intuitive bets. In this example, it may appear that TeamB (max strength of 16) is superior to TeamA (max strength of 10). But if you look at average strengths, TeamA comes out on top (8 to 7). How should these factors be evaluated?

Press calculate, and the resultant probability distribution indicates that the “weakling” Team A only has about a 12% chance of losing to TeamB:


Furthermore, knowing the actual probability of 12% provides an added edge for intelligent odds-making … all in fun, of course.

Q&A: Ken Goldberg Discusses Telerobots, Androids, and Heidegger

Announcing The Design Master Expert Assistant

DMXAnnouncing the Design Master Expert Assistant with the release of Design MasterTM V8

The DMeXpert™ (DMX) Edition guides the user with pop-up instructions, component selection lists, standard part values, important formulas, and a variety of other tips that are activated when entering a Formula cell. It’s like having a design/analysis expert at your side.

DMX is ideal for the design engineer or project manager who needs quick and efficient “fill in the blanks” design validation in minutes rather than weeks. Based on DACI’s thorough and practical worst case analysis plus (WCA+) methodology, DMX uses expertly designed templates to facilitate analysis of a variety of standard circuits.

In addiDM8tion to its standalone function, DMX is an integral part of the just-released Version 8 of Design Master’s Professional Edition. DMX facilitates efficient organization and selection of circuit and part files, and also provides easy access to an organized array of tutorials and DMeXpert tips.

Circuit templates, part files, and help files can be accessed and edited by using the Professional Edition. This allows an organization’s design experts to use the Professional Edition to create DMX templates tailored to the needs of the company.

For more information, please click here.