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John.Dunn

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Consultant

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John.Dunn

's contributions
  • 04.22.2014
Two-Pi Winding
  • 04.08.2014
Too Ideal
  • 04.01.2014
  • 2 Comment(s)
Finding Stuff
  • 03.25.2014
  • 3 Comment(s)
Gold
  • 03.06.2014
  • 4 Comment(s)
Ohms per square
  • 02.20.2014
  • 13 Comment(s)
Speaker Wires
  • 02.10.2014
  • 1 Comment(s)
Pull-up Resistors
  • 02.20.2014
  • Speaker Wires
  • I've gotten this claim viva voce from the occasional audiophile. I've not seen written claims from cable manufacturers themselves, but on the other hand, they do make and sell the stuff.
  • 02.10.2014
  • Pull-up Resistors
  • If only to drive home a point, I have JUST come across a newly designed product in which the SN7414 is used.
  • 01.20.2014
  • LEDing it hang out: The downside of higher efficiency
  • Let's not forget about traffic signals made with incandescent lamps that don't ice up to the point of invisibility in the winter storms. Then comes the scary thought that some municipalities plan to use LEDs for street lighting too.
  • 11.30.2013
  • The R175A
  • It's rather humbling to realize that the R175 and R175A have rather complex structures that were developed at a time when there were no network analyzers or other sophisticated RF test equipment that we take for granted today. Somebody really had to have put in a lot of time in getting it right.
  • 12.26.2013
  • The Pythagoreans' beautiful fallacy
  • Courtesy of Pythagoras, please take a look at: http://licn.typepad.com/my_weblog/2011/07/the-unsolvable-problem-john-dunn-consultant-ambertec-pe-pc.html
  • 01.04.2014
  • Two-point-two tau
  • A mnemonic memory aid for this is that "tpct" equals "Tau" times the natural logarithm of the ratio of the total excursion (in this case "100") divided by whatever part of the excursion remains to be covered at time "tpct" (in these cases, "pct" for the falling curve or "100-pct" for the rising curve).
  • 12.22.2013
  • Ground Fault Protection
  • The transformer winding impedance is indeed low, but it isn't zero so it doesn't take too low a ground fault impedance to cause the two windings to produce a detectable alarm signal output.. Also, it's the low-side fault that is so insidious because there needn't be pyrotechnic events happening. You can have a current path there and not even know it. (Surprise!) By the way, this is not anything new. I once read a patent on the idea that dated back to 1969. The trouble is, I can't recall who the patent holder was.