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Good as gold
By Thomas Black, Digital Products Company -- 10/2/2008
When a vendor obsoletes a critical ADC, a system designer finds himself becoming an IC-packaging expert—and learns not to skimp on bond wires. |
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Passive part becomes aggressive
By Craig Hermann, Engineer -- 9/18/2008
A computerized phone-answering system works but fails diagnostic tests, while its 'backup' passes the tests but won't work. The engineer tasked with resolving the conundrum eventually corners a surprising villain. |
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The case of the stolen capacitor
By Glen Chenier, Teeter Totter Tree Stuff -- 9/4/2008
An engineering change order erases a design's input stabilizing capacitance, with costly results. |
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It’s an electromagnetic-mechanical world
By David R Bryce, Dataram Corp -- 8/21/2008
A father's lesson helps to reveal the culprit causing a noise spike in a magnetic pickup. |
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Dumping the noise
By Jim Christensen, Kris Design Services -- 8/7/2008
Tabletop rap elicits a puzzling click from a solid-state ultrasonic receiver design. |
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Ghost busting on the ocean floor
By Hugh Shane Mitre, 7/24/2008
Spurious images in a side-scan sonar system lead to a further mystery: Why did it take so long for someone to try putting the unit into self-test mode? |
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Too many cooks spoil the circuit description
By Steve Lubs, Department of Defense, 7/10/2008
It started out as a simple design idea describing a receiver for a TDM data stream. Then my boss got involved. And his boss. And his boss. |
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Theory of relativity visits “real-time” clock
By Vadim Demidov, Giesecke & Devrient, 6/26/2008
What would make a logic analyzer's internal clock run faster than real time, but only while being set? |
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One giant leap for “enhanced” hybrid
By Stephen Tomporowski, Kaman Measuring Systems, 6/12/2008
Space-bound product nearly fails to launch due to an "improved" circuit design that is anything but. |
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Temperature: Your worst enemy?
By Clark Robbins, GS Engineering, 5/29/2008
Temperature-induced system errors gave this design team cold sweats. After realizing that identical units were failing at different temperatures, the engineers learned a valuable lesson. |
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Laser goes to (trim) pot
By Glen Chenier, Teeter Totter Tree Stuff, 5/14/2008
The laser in a SONET transponder begins to behave erratically with varying temperature. Should the engineers blame the climate, or the human element? |
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Watch those power leads!
By Doug Marsh, Consultant, 4/25/2008
Accidental backward filter test proves detrimental to DIPs. |
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Finding clock glitches
By Glen Chenier, Consultant, 4/17/2008
Debugging this optical backplane problem required a sharp eye and a
darkened lab. |
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Semiconductor contamination: Not your usual suspects
By Martin DeLateur, Consultant, 4/2/2008
Heavy-metal contamination is clearly the culprit in a recurrent case of decreasing semiconductor yield. But where is it coming from? |
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The case of the 'bad' memory chip
By Pierre Renaud, Hardware Engineer, 3/20/2008
Is this switch failure due to bad hardware, or a previously dormant software bug? |
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Power, power everywhere but nary a watt to blink
By Walter Lindenbach, 2/27/2008
Clever design takes 550V-ac oil pumps offline to avert environmental disaster. |
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A helping hand: 64-bit counter design pays off, slowly
By Steve Lubs, Department of Defense, 2/21/2008
My boss didn't like my 64-bit counter design, but by sharing it as an EDN Design Idea I helped a fellow engineer. |
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The stalling power supply
By William Saks, Northrop Grumman, 2/7/2008
A test technician's unexpected toggling reveals the design flaw behind a power-supply failure. |
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Blown fuse has a meltdown
By Jim Sylivant, Engineering Consultant, 1/17/2008
Unusual construction gives fuse a "memory" for brief current surges. |
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Surprise, surprise: Intermittent power-on reset problem reveals decades-old secret of 8052
By Phil Ouellette, Mettler-Toledo Inc, 12/14/2007
Debugging a problem with a USB peripheral leads to the discovery of a little-known quirk of the venerable 8052 processor. |
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Mind the gap: What separates a failing transformer-isolated interface from a flawless protoype?
By Jeff Fries, GE Transportation, 12/3/2007
Do your qualification testing on a design that best represents what will come off the actual production line. |
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What color is 10 kΩ?
By John Linstrom, S&K Electronics and Sunspot, 11/8/2007
A code held the key to building a board with the right resistors. |
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Outdoors-only LCD malfunction puzzles portable-product designers
By Chris Lee, Cheshire Engineering Corp, 10/25/2007
Chips and software don't always just snap together and work, and your engineering education began with basic science for a reason. |
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Time bomb: The case of the invisible failure mode
By Walter Lindenbach, Calgary Controls Ltd, 9/27/2007
An unexpected voltage spike compromises a monitoring device's reliability. |
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Solid-state physics convinces customers
By Martin Delateur, Consultant, 8/16/2007
Yes, semiconductor performance does change with temperature. |
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Avalanche: Overwhelming input voltage sets off cascade of process-controller failures
By Walter Lindenbach, 7/19/2007
Semiconductor junctions have a “reverse breakdown voltage” at which a reverse-biased junction begins to conduct. This situation is unhealthy for sensitive op-amp input transistors. |
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The eyes have it: Failing amplifier boards no match for engineer's keen vision
By Jerome Johnston, Cirrus Logic, 6/21/2007
When all else fails, don't forget to eyeball the board. |
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Silence in the sanctuary: Quieting a suddenly noisy electret microphone
By Dick Neubert, Electronics Engineer, 6/7/2007
Why did a formerly quiet mic fall victim to electrostatically coupled noise? A church sound man's intervention yields divine results. |
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The power of the hot seat: Engineer vanquishes signal-integrity problem, red tape
By Reed P Tidwell, Xilinx, 5/24/2007
Getting this multimillion-dollar flight-simulator system out the door required massive rework, persuasion of upper management, and a frantic signoff process. |
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Beware of what you think you know: What's silencing this digital guitar-amp design?
By Kenneth Ciszewski, Tech Electronics, 5/10/2007
Showstopping bugs can arise even in seemingly elementary design tasks, such as generating a serial connection clock or programming some EPROMs. |
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Answers can be anywhere: Unlikely culprit takes down test system
By Clark Robbins, GS Engineering, 4/26/2007
Is a software bug to blame for a failing automated-test system, or could the problem lie elsewhere? Sometimes it pays to listen to any suggestion—even one from a student. |
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Fooled by a thermocouple: Temperature sensing gone awry
By Ken Whiteleather, Sparton Corp, 4/12/2007
What can explain an infrared temperature sensor's unique "proximity-sensing feature," whereby the measured temperature rises whenever someone approaches or touches the system? |
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The smallest change necessary: Wise boss imparts important design principle
By Robert Cravotta, Technical Editor, 3/29/2007
Re-engineering a system from the ground up may be tempting, but seasoned designers know the wisdom of changing only enough to accomplish the objective at hand. |
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Serendipity revisited: Fortuitous capacitor solves RF-reception problem in garage-door opener
By Marvin Collins, 3/15/2007
A former radio-station engineer recalls how a capacitor in his pocket helped keep peace on the homefront. |
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RF emissions and FCC Part 15: EMI woes and cures
By Glen Chenier, Teeter Totter Tree Stuff, 3/1/2007
My first exposure to EMI (electromagnetic-interference) measurement was in trying to make my multiport, unshielded-twisted-pair Ethernet-hub card comply with FCC Part 15 Class A in a multicard chassis that leaked RF like a sieve. |
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In the days of old, when engineers were bold
By Lynn Smith, 2/15/2007
An intermittent problem in the current model causes a watchdog timer to reset a security-monitoring system, resulting in disturbing false alarms. Is hardware or software to blame? |
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You're gonna do what with an LCR bridge?
By Paul L Schimel, Fairchild Semiconductor, 2/1/2007
A long time ago, when I still thought I was smart, I had just finished a transformer design and handed it off to the in-house magnetics shop. There, I learned about a technique that left me a little baffled. |
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One man's trash: How I made a tidy profit on unwanted VMEbus card cages
By Marty McGrath, McGrath Technical Services, 1/18/2007
The kicker came when I got a frantic call from a purchasing agent from the same company from which I had originally obtained the nine pallets. |
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Testing our reliance on testing: Worst-case scenarios in mixed-signal design
By Bob Mason, Schneider Electric/Square D, 1/4/2007
This situation was another example of why not to rely on testing to determine a design's limits: You will rarely encounter worst-case parts. |
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Hit the ground running- Detective work revives vintage vector voltmeter
By Walter Lindenbach, 12/1/2006
Something in the unit had degenerated. So, I measured every waveform and voltage that could pertain to the PLL. |
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Where does the energy go?
By Ron Mancini, 11/9/2006
Replacing failed TO92 transistors with TO5 transistors reduced the failure rate from 60 to 1.5%. But failing 1.5% of the time is still garbage in my book. |
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Serendipity saves the day: Capacitor tames mysterious MRI noise gremlin
By Billy Sevel, Fairchild Semiconductor, 10/26/2006
Years ago, I was a design engineer for a medical-imaging company producing MRI (magnetic-resonance-imaging) equipment. Even though I was not an RF engineer, the designs I worked on had to deal with RF-noise problems all the time, mainly within the shielded room where the magnet resided. |
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Sidebands be gone, or let there be (no) light
By James Long, PhD, 10/12/2006
The prototypes had come in, and I was pleased with much of the design. There was one problem, though: spurious sidebands on the synthesizer output. |
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Specs: Sometimes timing really is everything
By Margery Conner, Technical Editor, 8/17/2006
Be careful if you rely on device performance that you've merely observed and not specified. |
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Sweating blood over hardware-interface routines
By Peter Hiscocks, Syscomp Electronic Design Ltd, 7/20/2006
In the 1980s, I obtained a number of consulting contracts to put the Vinten aerial photo camera and various other sensing devices into fixed-wing and helicopter aircraft. |
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Targeting multifarad backup capacitors (and tricky clients, too)
By Jerry Durand, Durand Interstellar Inc, 6/22/2006
Every contract-design company has at least one "interesting" client who presents you with unique and difficult challenges. |
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Version inquiry
By Robert Cravotta, Technical Editor, 3/2/2006
I was supporting the system-build and -integration effort, in the field, of an R&D flight system. The system was an iterative evolution of a quick and dirty proof-of-concept vehicle that the team had demonstrated several months previously. |
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Hardware designer on an electric chair
By Thomas Blinn, Siemens AG, 2/2/2006
My engineering team was designing a signal-processing board for the mobile-radio infrastructure. The board integrates a number of DSPs and ASICs for number-crunching. |
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Valuing uncertainty
By Robert Cravotta, Technical Editor, 1/5/2006
Dealing with uncertainty is fundamental to being an engineer, and there is usually a positive correlation between the seniority of an engineer and the amount of uncertainty he needs to deal with in his job. |
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Skunkworks project ends up smelling like a rose
By Danis Carter, Tyco Healthcare, 12/5/2005
A fellow project team member encountered difficulty stabilizing a pneumatic valve developed from a skunkworks effort. His voice-coil-driven valve offered a new technology to our industry, and we were looking at the feasibility of using it as an exhalation valve in a new medical ventilator. |
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Parts are parts
By Charles Clark, Pratt & Whitney Rocketdyne, 11/10/2005
In the mid-1960s, when I began designing circuits for military applications, many military-rated parts were available. We still had to occasionally qualify a "nonstandard" part, but it was not a huge ordeal, because manufacturers made the parts mostly in the same way as the military parts—with semiconductors, many capacitors, and other parts in hermetic packages. |
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Coping with changes of employment
By Charles Clark, 10/13/2005
A few weeks ago, Boeing completed the sale of the Rocketdyne operation, where I work, to Pratt & Whitney. P&W (part of UTC) is the ninth company I've worked for in the last (almost) 40 years. I carefully picked my first job in 1966, interviewing with and comparing dozens of companies. |
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Something from nothing
By Jim Williams, Linear Technology, 9/15/2005
In the early 1980s, as Linear Technology was just beginning, we had a fundamental problem: products in development but none to sell. But, we wanted prospective customers to know our name and what we were up to. Our public-relations company glibly urged "controlling the press" and "getting our message out" but offered little real substance. |
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Shedding light on radiation testing
By Charles Clark, The Boeing Company, 8/18/2005
We recently designed a 2-kW, more-than-93%-efficient power converter for a manned space application. The design uses the latest generation of 500 and 200V power MOSFETs, which are available as commercial encapsulated plastic parts, for both converter-drive and synchronous rectification. |
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Watching the currents flow
By Dmitrii Derevensky, 7/21/2005
It was late Sunday evening, and we were still trying to trace why the embedded DSL modem was feeding a strange 50-MHz carrier into the network—much stronger than -40-dB noise allows. And no 50-MHz signal existed on the design! |
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Baby steps stop the crying
By Danis Carter, Tyco Healthcare, 6/23/2005
Sometimes, a seemingly insignificant part tempers the thrill of a technical accomplishment. That's what happened to me recently when I designed and built a Battlebot that I thought was verified and ready to run. Instead, repeated failures brought me to my knees. |
