Michael Dunn

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EiC

Michael Dunn is editor-in-chief of EDN, and has been messing with electronics almost as long as he's been walking. He got his first scope around age 15, and things have been going downhill ever since. The scopes now vie with wine racks, harpsichords, calculators, and 19th century pianos for space. Over the years, he's designed for the automotive, medical, industrial, communications, and consumer industries, as both freelancer and employee, working with analog, digital, micros, and software. Since 2000, he's run the TekScopes Yahoogroup, now with over 5,000 members. He was previously editor-in-chief of Scope Junction: http://edn.com/collections/4422580/Scope-Junction-blogs


Michael Dunn

's contributions
  • 03.07.2017
  • Measuring appliance power consumption
  • I wonder if there's a universal algorithm to calculate power factor. Must be. Though as I mentioned in my 12V adapter article, a Kill-a-Watt can be fooled: http://www.edn.com/electronics-blogs/benchtalk/4441809/My-kingdom-for-a-12V-adapter "Interesting sidebar: I plugged the XY1205A into my “Kill-a-Watt”, and calculated a conversion efficiency of about 110% based on the wattage reading! (PF=0.52) This must be a Kill-a-Watt issue with more outrageous current waveforms."
  • 04.01.2016
  • Designer's Notebook: Discrete Logic
  • I remember a crazy experience bringing up that synthesizer module. The design used a couple of 4-bit comparator chips, and the only CMOS parts I could find were part of a "slightly" proprietary line from a company I forget (Unitrode or something similarly exotic). I remember the part number to this day: 40085 (not 4085 as you might expect). My understanding was that this had the same functionality as the common 7485 TTL part. It did...sort of. I turned the module on for the first time, and that part of the circuit simply wasn't behaving in any reasonable way. Could the chips be bad? Remember, this is ~1978...I couldn't just hit the Web. But eventually I got my hands on the official pinout of the 40085. It *did not* match the 7485! Argh. What it *did* match was the 74L85!!! For reasons I may never know, the low-power TTL sub-family used different pinouts than all the other sub-families. Understandably, the 40085 maker figured that 74L85 replacement could be a lucrative market, so they copied that pinout instead of the normal one. Amazingly, the ICs survived their miswired application.
  • 03.01.2017
  • Grammar and the engineer
  • Perhaps that's how it was back in the 1930s. Note that the little-used deca (10) & hecto (100) prefixes are also lower-case (hectolitres are sometimes seen (e.g., in viticulture)). https://en.wikipedia.org/wiki/Metric_prefix And as far as I'm concerned (especially in this day and age of ELECTRONIC typewriters and other such marvels), "u" is never an acceptable substitute for "µ".
  • 02.03.2011
  • Control an LM317T with a PWM signal
  • The ripple will be ~0.2% FS, which might be bearable. If not: - Increase f(pwm), and/or - Increase RC, and/or - Optimize PWM waveform (MLS, bit reversal (see "Free DAC" link above))
  • 03.01.2017
  • Grammar and the engineer
  • A highway sign in my neck of the woods announcing an upcoming restaurant reads: Pasta's Burger's Lobster's etc. Always good for a chuckle, I try not to let it make me crazy.