Oh boy. All these years I’ve been waiting for my wife to ask how this plane stays up in the air. But alas she never does. I try to explain why the tires need to be checked in the winter but no comprende’. I say what if I’m not around? And I get the reply “I’d just hire someone”. I can only imagine the joy of someone really interested in the secrets of life. What the heck is a Kelvin scale though? Is that like a fixed asset?
It’s a temperature scale used by physicists. Zero degrees Kelvin, called “absolute zero” is that theoretical point at which all atomic activity ceases. As atoms nears absolute zero, their behavior changes dramatically. That’s some of the stuff theoretical physicists ponder, the behaviors of subatomic particles as they approach absolute zero. If you’ll pardon the pun, it’s cool stuff.
the behavior or materials at extremely low temps is really interesting stuff.
I don t believe in dumbing down conversations to suit the audience. too often we underestimate people. the wording may have to be adjusted to fit the vocab. of the listener, but the theory is usually understandable to most people if you take the time to explain it and use terminology that they understand.
acronyms and technical jargon are only understood by folks who already have some knowledge of a subject. the common computer terms used online are often mysteries to me, as I chose (stupidly) to avoid computers until last year. that does not mean I don t understand the capabilities of computers, as I kept myself well informed and read two or three newspapers a day for many years, I just don t know how to utilize those capabilities and don t know many of the technical terms used to describe computer functions.
I can read 17th and 18th century English without trouble. ben franklins autobiography is brilliant stuff, and relevant today, but would be hard for a casual reader to read because many of the words had different meanings back then. the basic theories and lessons are simple, its just the wording that make it hard for many to read. i have to use old, old dictionaries when playing scrabble or many of my words will not be listed. I grew up with a book in my hand always, and have even walked into a lamp post once, while reading, when i was in elementary school, but a computer manual is unhelpful at times because I don t know the jargon or understand how to accomplish he simple things that they take for granted that I already know.
I often type out things, instead of using abbrev. on this site, just so the casual visitor is not lost in acronyms and auto jargon, as I sometimes am myself.
Disconnecting the output (big red) wire from the alternator breaks the drainage path, no need to un-ground the alternator.
Hang an ammeter or test light from the wire to the alternator terminal to measure for drain.
@Bing, blow up a balloon with air and put it in the freezer. That’ll show wifey why we add air to tires in the winter.
Smokey Yunick (I’m reading his autobiography) on tires (tars), wet vs dry air and nitrogen:
“[In the late '40s & 50’s]We used regular compressor air. Yup, with lots of moisture, which caused the tire pressure to build up, say ten pounds. Well, this was supposed to be bad regarding handling. The harder the tires, as a general rule, the less your lateral traction will be. So I tried nitrogen. My observation was, hell, that didn’t help. Maybe made it even worse. How come?That nitrogen was not totally moisture free so we got a little better lateral traction, but blew and blistered worse. Why? The wet air out of a compressor on a hot humid day would condense the moisture to steam in the tire. Water boils at 212 degrees at sea level, right? Tire air temperature 250 to 300 degrees F, so even at 50 pounds pressure the moisture turns to steam, the steam evened out the hot spots in the tire. This gave us a few more miles before the shotgun went off. Yup, that is how it sounded. You could hear it over the engines.”
Eyes glassing over . . .
Under normal conditions those extra diodes won’t pass any current because the peak voltage on the center tap is half of what’s on the outer arms.
Maybe they come into play during spikes or surges.
On pre-computer cars that center tap voltage was used to turn the dashboard alt warning light OFF.
Like I said, I’m a parts replacement guy. If I think a part is bad I just replace it. Once in a while do some looking for burned components or obvious evidence of failure just to impress family. Its been over 40 years since anyone tried to instruct me on reading schematics and I’m pretty happy with that. Now ask me about ROI or net present value or something interesting.
The Kelvin scale is the same as the Celsius scale, except that 0 Kelvin is about -273 Celsius, and therefore 0 Celsius is about +273 Kelvin.
By definition, 0 Kelvin is the complete absence of heat, meaning that it is absolute zero, the very coldest temperature possible anywhere.
As for the 8 diodes, it looks to me like the two diodes coming from the neutral are there only to improve reliability. With them installed it would take a failure of at least two diodes to make the rectifier stop working.
I wish I would have known that last winter in Minnesota. I could have told the wife, its not cold, its about +200 degrees out.
Eight diodes, no so new. From the 1978 MOTOR Auto Repair Manual:
For the record, 200 Kelvin, or -73 degrees Celsius is about -100 degrees Fahrenheit.
If that’s really how cold it was, you can tell her whatever you like, she’s gonna insist it’s cold!
The seperate parts you mentioned will likely cost considerably more than a quality rebuilt alternator these days @Bing. And as for those Kelvins, it’s way to much trouble to scale them. Get a good fillet knife.
Jay, that point at which there is no temperature IS that point at which all atomic activity ceases. That is how absolute zero is defined, and how absolute zero is determined, by the absence of atomic activity, the activity having ceased.
re: conversions, the attached link might interest you
bump
One variation I have seen in the rectifier bridge is zener diodes in the 3 gounded diodes. This was in a GM alternator.
The phase voltage of the stator winding would appear across those diodes when the diode to the positive output terminal was conducting. If the field current was excessive, any overvoltage spikes would be clipped by tho zener diodes, saving the electronics from the spikes.