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Quote:
Originally Posted by Rich-n-Texas
Mr. Irwin, my high school electric shop teacher got pretty angry with me when I answered a test question with what I posted above. That's the honest to Gawd truth. On the bench's instrument panel in front of me, the voltmeter had the banana jacks with the ground connection on the left and the positive connection on the right. I did ultimately pass the test though. :o
Oh yeah? What about on the other side of the equator - huh, huh? :) :) :)
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Originally Posted by hermanv
I hate to be picky (Not true, I love being picky). Electrons flow from negative to positive, current flows from positive to negative.
hermanv, stop being so picky :D
In electronic schematic labeling, by default the direction of current (+ to -) is shown as oppose to direction of electrons (- to +). This way negative or ground can be used as a reference point (0 V).
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Quote:
Originally Posted by Smokey
In electronic schematic labeling, by default the direction of current (+ to -) is shown as oppose to direction of electrons (- to +). This way negative or ground can be used as a reference point (0 V).
Does your handle refer in any way to what you do for relaxation? :D :D :D
Seriously though, the highest voltage is usually drawn on top. For the majority of designs that is the positive supply (like in all tube circuits). For telephony -48VDC is the highest voltage so it is drawn on top. Unseasoned fresh graduates often draw it with negative 48V on the bottom, they are sneered at by old hands.
The telephony people learned quickly that buried wire dissolved due to electrolysis when the minus battery terminal was grounded. By tying th positive terminal to ground the -48V on the buried cables causes the conductors to slowly get bigger.
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Quote:
Originally Posted by hermanv
Does your handle refer in any way to what you do for relaxation? :D :D :D
That is for me to know, and for you to find out :p
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For telephony -48VDC is the highest voltage so it is drawn on top. Unseasoned fresh graduates often draw it with negative 48V on the bottom, they are sneered at by old hands
That make sense too, as again 0 Volts (ground) is used as the reference. The only difference is that current flow is now reversed and hopefully new graduate label it as so. Current now flow from the ground :)
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The telephony people learned quickly that buried wire dissolved due to electrolysis when the minus battery terminal was grounded. By tying th positive terminal to ground the -48V on the buried cables causes the conductors to slowly get bigger.
That is interesting. When you are refering to -48DCV battery terminals, is ground (0V) positive or negative terminal?
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Originally Posted by hermanv
Oh yeah? What about on the other side of the equator - huh, huh? :) :) :)
"Warning, warning!" "Danger, danger!" "Danger Will Robinson!" "That does not compute!" "That does not compute!" :crazy:
Quote:
Originally Posted by Smokey
That is for me to know, and for you to find out :p
"The truth will set you free" :biggrin5: Hey Smokey, how 'bout participating in my Iron Man... thread? I might just go see it tomorrow night. I think it's getting pretty good reviews. :thumbsup:
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Quote:
Originally Posted by Smokey
<snip>
That is interesting. When you are refering to -48DCV battery terminals, is ground (0V) positive or negative terminal?
Sorry I wasn't clear. Occasionally in the rush to post a reply you say what seems quite clear at the time and when you look at it later it was crap.
If you ground the negative terminal all the telephony wires end up positive with respect to Earth ground, so if the negative battery terminal was grounded the wires slowly dissolved. For modern telephony the positive battery terminal is the one that's grounded, leaving the wires with a net negative charge.
To understand what's going on, loop up electroplating. Atoms (Ions actually) are leached from the positive electrode and deposited on the negative electrode. In this case when the battery negative terminal was grounded, copper was removed from the wires and distributed into the dirt surrounding the cable and when the battery positive terminal was grounded, atoms moved from the dirt to the wires.
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Originally Posted by Rich-n-Texas
""The truth will set you free" :biggrin5: Hey Smokey, how 'bout participating in my Iron Man... thread? I might just go see it tomorrow night. I think it's getting pretty good reviews. :thumbsup:
Saw that thread and reason I didn’t participate was that haven’t seen previews or the movie, so really didn’t know what to say. If you see it, please give us a review in FF :)
Quote:
Originally Posted by hermanv
If you ground the negative terminal all the telephony wires end up positive with respect to Earth ground, so if the negative battery terminal was grounded the wires slowly dissolved. For modern telephony the positive battery terminal is the one that's grounded, leaving the wires with a net negative charge.
To understand what's going on, loop up electroplating. Atoms (Ions actually) are leached from the positive electrode and deposited on the negative electrode. In this case when the battery negative terminal was grounded, copper was removed from the wires and distributed into the dirt surrounding the cable and when the battery positive terminal was grounded, atoms moved from the dirt to the wires.
Learn something new everyday. Thanks for info.
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Like I said, I EVEN HAVE TROUBLE getting people to beleive that current flows from negative to positive (which is the case) :1:
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Quote:
Originally Posted by Rich-n-Texas
"Warning, warning!" "Danger, danger!" "Danger Will Robinson!" "That does not compute!" "That does not compute!" :crazy:
"The truth will set you free" :biggrin5: Hey Smokey, how 'bout participating in my Iron Man... thread? I might just go see it tomorrow night. I think it's getting pretty good reviews. :thumbsup:
It is, and Paltrows legs are getting even better reviews:1:
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Originally Posted by pixelthis
Like I said, I EVEN HAVE TROUBLE getting people to beleive that current flows from negative to positive (which is the case) :1:
Current flows from positive to negative, electrons flow from negative to positive.
http://www.mste.uiuc.edu/murphy/Hole...tricFluid.html
Actually no one cares. :)
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Originally Posted by hermanv
current IS electrons, voltage the "pressure" in a water pipe.
I saw a cartoon in todays paper, people were walking into the "cemetary of last words",
on one tombstone it said "wheres the ripcord?".
On another it said "AC or DC , whats it matter"?
So some should care :1:
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