Anyone who has ever watched a thunderstorm is aware of what sparks can do underneath the fitting circumstances, the identical goes for anybody who has ever watched the Boris Karloff film, “Frankenstein”. Nevertheless, improperly extrapolating these observations to the lab bench is just not a good suggestion.
I’m going to vent a little bit bit right here so prepare.
There was this microwave energy meter which was having operational failures that had been wrongly blamed on damages to its energy sensing thermistors. That was not really the case. The thermistors themselves weren’t being harmed by something.
Finally I made circuit design revisions which solved the working drawback at hand. However till that was performed, fictitious suppositions have been being improperly bandied in regards to the firm and, to make use of a typical vernacular, “They’d legs.”
A falsehood can go across the globe ten instances whereas the reality remains to be attempting to go away the parking zone.
Thermistor energy was really fairly low with DC bias currents down within the milliamp vary. Sadly, an ill-informed colleague unfold a narrative to inept firm administration saying that when energized, the thermistor assemblies have been being disconnected by unplugging them from their cable connectors, sparks have been occurring on the parting connector pins and that these sparks have been delivering damaging power to the thermistors (Determine 1).
Determine 1 The inaccurate thesis on why the microwave energy meter was having operational failures. Supply: John Dunn
If there had been any sparking occurring as in Determine 1, the impedance(s) of these sparks would have arisen in sequence with the impedances of the thermistor, the resistances of the wires, the supply impedance of the driving amplifier and the enter impedance of the monitoring circuitry.
Such hypothetical sparks wouldn’t all of the sudden be dumping some saved reserve of power. No matter present may need been flowing simply earlier than connector pin separation might solely go downward, not upward. Thus, the thermistors have been fairly secure from that alleged supply of hurt.
Even so, the corporate’s technologically inept administration (I might have used extra precisely descriptive although much less well mannered terminology) was led to consider that there should in some way have been some form of harmful power discharge occasions occurring just like the ½LI² of an car ignition coil getting all of the sudden open circuited or the ½CV² of a charged capacitor getting all of the sudden quick circuited. Administration turned completely and wrongly satisfied that I simply wasn’t trying on the concern correctly.
Truly, the thermistor monitoring circuits have been themselves at fault which was the issue I fastened whereas ignoring my colleague and whereas ignoring administration. I made a number of design revisions which corrected a number of operational issues.
The end result was successful! All the pieces labored okay from then on.
“Reality at all times prevails ultimately.” -Lord Acton, English Thinker, Editor and Professor of Fashionable Historical past at Cambridge College, 1834-1902.
After all, when the reality doesn’t prevail…
John Dunn is an electronics marketing consultant, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York College (MSEE).
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