Join Early Retirement Today
Reply
 
Thread Tools Search this Thread Display Modes
Old 06-25-2014, 08:16 PM   #41
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: Sep 2005
Location: Northern IL
Posts: 18,278
Quote:
Originally Posted by Fermion View Post
Here is a little tidbit. Did you know that electrons in a wire only move about 3 inches an hour? Talk about slow!
Right, it is a wave (but I actually was unaware of those numbers - interesting).

But it it so much more 'fun' to imagine our little electrons zipping through the wires in their little hot rods, leaning into the tight turns!

But like this little desk toy, the center balls barely move, but the wave propagates very quickly.





ooops, I missed a bunch of posts while I was writing this and doing other things! Oh well, it might still fit.


-ERD50
__________________

__________________
ERD50 is offline   Reply With Quote
Join the #1 Early Retirement and Financial Independence Forum Today - It's Totally Free!

Are you planning to be financially independent as early as possible so you can live life on your own terms? Discuss successful investing strategies, asset allocation models, tax strategies and other related topics in our online forum community. Our members range from young folks just starting their journey to financial independence, military retirees and even multimillionaires. No matter where you fit in you'll find that Early-Retirement.org is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with our members, see fewer ads, upload photographs, create a retirement blog, send private messages and so much, much more!

Old 06-25-2014, 08:21 PM   #42
Thinks s/he gets paid by the post
 
Join Date: Sep 2012
Location: Seattle
Posts: 2,905
To understand better EM propagation, especially in a vacuum (where there is no obvious medium like the water in the hose example), try Richard Feynman's book, "QED, The Strange Theory of Matter and Light".

I haven't read it in a long time. I should reread it. It is like $11 on Amazon.
__________________

__________________
Fermion is offline   Reply With Quote
Old 06-25-2014, 08:26 PM   #43
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
NW-Bound's Avatar
 
Join Date: Jul 2008
Posts: 19,403
Quote:
Originally Posted by imoldernu View Post
Re: electron flow... I had it explained to me, that the electrons don't actually move on a wire, but rather are absorbed by the atoms that constitute the transmission medium (in this case wire)... and thereafter being thrown off to the next atom, and so on down the line...
Yes. Each copper atom has one free electron (not all electrons can escape from their orbit), and this free electron can jump from one atom to the next.

By the way, in contrast with electron speed in a wire, free electrons inside a CRT of the old TVs do actually move very fast in a beam. I remember speed numbers like 1/4 the speed of light.

Knowing that electrons in a TV CRT are accelerated by a potential of 20+KV, I can sit down and verify the above speed number, but will not. I have problems with placing decimal points, as you have seen.
__________________
"Old age is the most unexpected of all things that can happen to a man" -- Leon Trotsky
NW-Bound is offline   Reply With Quote
Old 06-25-2014, 08:30 PM   #44
Thinks s/he gets paid by the post
target2019's Avatar
 
Join Date: Dec 2008
Posts: 3,705
When you're looking at costs and savings, the next kWh you save is more expensive than the average. Say my average is a dime, I use 15 cents when I calculate the cost of running an additional fan, for instance.
__________________
target2019 is offline   Reply With Quote
Old 06-25-2014, 08:35 PM   #45
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: Sep 2005
Location: Northern IL
Posts: 18,278
Quote:
Originally Posted by NW-Bound View Post
True.

But how do you explain in simple terms to a layman ....

shhhhhh! You don't explain it in simple terms to a layman! Don't you remember the oath we all took? How are we going to make the big bucks and seem 'special' (yes, I'm throwing an easy one across the plate, trying to make it too easy to be worth an 'attack'!) if everybody understands this stuff?

One more slip, and you will be sent back for 'reprogramming'.


Quote:
Originally Posted by Fermion View Post
Harder to explain to a layman is an electric field propagating in a vacuum. Actually that is hard to explain to a EE student.
Or even someone who hasn't thought much about that since he was a student, a long time ago.

-ERD50
__________________
ERD50 is offline   Reply With Quote
Old 06-25-2014, 08:39 PM   #46
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: Sep 2005
Location: Northern IL
Posts: 18,278
Quote:
Originally Posted by target2019 View Post
When you're looking at costs and savings, the next kWh you save is more expensive than the average. Say my average is a dime, I use 15 cents when I calculate the cost of running an additional fan, for instance.
Depends. If you are not on tiered rates, that's not the case. And if you have fixed fees and are on a single rate, the marginal rates are actually lower than average, but it's rather meaningless if you can't do anything about the fixed rate portion. But mathematically, that first kWh is expensive.

-ERD50
__________________
ERD50 is offline   Reply With Quote
Old 06-25-2014, 08:42 PM   #47
Moderator Emeritus
 
Join Date: Oct 2007
Posts: 4,929




Reduction to practice is an exercise left for the reader.
__________________
M Paquette is offline   Reply With Quote
Old 06-25-2014, 08:53 PM   #48
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
NW-Bound's Avatar
 
Join Date: Jul 2008
Posts: 19,403
Just mention electrons and a thread starts drawing in nerds like you couldn't believe...
__________________
"Old age is the most unexpected of all things that can happen to a man" -- Leon Trotsky
NW-Bound is offline   Reply With Quote
Old 06-25-2014, 09:03 PM   #49
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
Lsbcal's Avatar
 
Join Date: May 2006
Location: west coast, hi there!
Posts: 5,677
Quote:
Originally Posted by Fermion View Post
To understand better EM propagation, especially in a vacuum (where there is no obvious medium like the water in the hose example), try Richard Feynman's book, "QED, The Strange Theory of Matter and Light".

I haven't read it in a long time. I should reread it. It is like $11 on Amazon.
I have it but got distracted. Probably by NW-bound in some stock market threads.

Guess I don't have any excuses now. Thanks for the pointer.
__________________
Lsbcal is offline   Reply With Quote
Old 06-25-2014, 09:20 PM   #50
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
NW-Bound's Avatar
 
Join Date: Jul 2008
Posts: 19,403
I had a few books by Feynman, but not that one.

Arghh... Why would I want to get back in something like this? I begin to wonder if I will ever build anything again, or write any more software or firmware. Two scopes, 4 signal generators, two spectrum analyzers, only one has been turned on recently.

I like money too much, and counting it is easier. Actually Quicken does all the counting, as I do not even have to add up the numbers. I am getting soft, really soft...
__________________
"Old age is the most unexpected of all things that can happen to a man" -- Leon Trotsky
NW-Bound is offline   Reply With Quote
Old 06-25-2014, 09:31 PM   #51
Thinks s/he gets paid by the post
 
Join Date: Sep 2012
Location: Seattle
Posts: 2,905
I bought a 3000 series Agilent 500mhz 4 channel MSO and haven't turned it on in five months. They might not even be called Agilent anymore by the time I turn it on again.

Life gets in the way of engineering. Or thinking about early retirement.

I tend to go in spurts though. Nothing for a couple years then I will get into some digital or analog project and spend every waking minute on it.
__________________
Fermion is offline   Reply With Quote
Old 06-25-2014, 09:41 PM   #52
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
Lsbcal's Avatar
 
Join Date: May 2006
Location: west coast, hi there!
Posts: 5,677
Quote:
Originally Posted by NW-Bound View Post
I had a few books by Feynman, but not that one.

Arghh... Why would I want to get back in something like this? I begin to wonder if I will ever build anything again, or write any more software or firmware. Two scopes, 4 signal generators, two spectrum analyzers, only one has been turned on recently.

I like money too much, and counting it is easier. Actually Quicken does all the counting, as I do not even have to add up the numbers. I am getting soft, really soft...
A clear market top signal.
__________________
Lsbcal is offline   Reply With Quote
Old 06-25-2014, 09:51 PM   #53
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
NW-Bound's Avatar
 
Join Date: Jul 2008
Posts: 19,403
Yep. In a few more months, may have to get back in the game to make a living when the market craters.

"Have scope. Will travel".
__________________
"Old age is the most unexpected of all things that can happen to a man" -- Leon Trotsky
NW-Bound is offline   Reply With Quote
Old 06-25-2014, 11:25 PM   #54
Thinks s/he gets paid by the post
Telly's Avatar
 
Join Date: Feb 2003
Posts: 1,448
Quote:
Originally Posted by NW-Bound View Post
The following site has more info on the ringing voltage and waveform: Telephone ringing circuits.

As a kid, I opened up a telephone and traced its internal wiring. Found that there was a capacitor in series with the electromagnet coil of the ringer. The cap was to block DC current, but I assumed that it would also resonate with the inductance of the coil for more power to toggle that hammer.

I have not thought about this in years. I do not know if I care to hook up my scope to the phone line to see if they send down sinewave or squarewave to ring it, though I am sure either would work. If there's money in it, I would do it. Getting lazy here...
.
That link is very broad, and has some incorrect/misguided info!

The purpose of the cap in the ringer IS to block DC current flow, or else the ringer would be detected as an off-hook.
Some multiparty ringing schemes of old used resonant ringers (Decimonic, Synchromonic, Harmonic). The 4-party divided ringing scheme did not, and neither does single-party.

Ringing is ~90 - 130 RMS VAC sine wave. Even in the old days. Regardless of the frequency used. A square wave is to be avoided, as the steep transitions are loaded with high-order harmonics, which radiate all over and couple into everything.
__________________
-- Telly, the D-I-Y guy --
Two fools dancing on the hands of time
Telly is offline   Reply With Quote
Old 06-26-2014, 04:06 AM   #55
Thinks s/he gets paid by the post
 
Join Date: May 2014
Location: Utrecht
Posts: 2,212
Quote:
Originally Posted by imoldernu View Post
No good place to start, so:

1. Do you know how to calculate your base cost for electricity? Ie. can you give a single answer for the question: What was your total cost per Kilowatt Hour last month. Total cost... not the delivery, not the equalizer, not the taxes, not the contract cost or the state taxes or any other part of the confusion that could make up you electricity bill. Answer should be like this:
$.124 /KWH.
Since I rent all-in regardless of what I use, one could argue my cost per kilowatt hour is zero.

That said, commercially costs in NL are around $.135 / kwh (including all costs). Retail most pay around $0.20 or so.
__________________
Totoro is offline   Reply With Quote
Old 06-26-2014, 07:46 AM   #56
Thinks s/he gets paid by the post
target2019's Avatar
 
Join Date: Dec 2008
Posts: 3,705
Quote:
Originally Posted by ERD50 View Post
Depends. If you are not on tiered rates, that's not the case. And if you have fixed fees and are on a single rate, the marginal rates are actually lower than average, but it's rather meaningless if you can't do anything about the fixed rate portion. But mathematically, that first kWh is expensive.
To be honest, I don't understand my bill. It is very complicated, and has a comparison rate, like .10 per kWh.

This page gets updated with costs by state, so probably more useful to those who need the average cost of a kWh.

EIA - Electricity Data
__________________
target2019 is offline   Reply With Quote
Old 06-26-2014, 08:10 AM   #57
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
travelover's Avatar
 
Join Date: Mar 2007
Posts: 9,880
Re USB charging, I've noticed that the iPad won't charge off a cheap 0.5 or 1.0 amp 12 volt converter. It needs at least 2.0 amps or it won't attempt to charge at all. I'd expect it to charge, but more slowly.

My Nook HD Plus won't charge off any USB except the Nook provided wall wart - evidently it senses non-Nook branded chargers and just deactivates the charging function.
__________________
Yes, I have achieved work / life balance.
travelover is offline   Reply With Quote
Old 06-26-2014, 08:30 AM   #58
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
NW-Bound's Avatar
 
Join Date: Jul 2008
Posts: 19,403
Quote:
Originally Posted by Telly View Post
...
Some multiparty ringing schemes of old used resonant ringers (Decimonic, Synchromonic, Harmonic). The 4-party divided ringing scheme did not, and neither does single-party...
Spoken like a telephone expert.

I have never heard of these terms. I guess fewer and fewer will know about the above. I have wondered about your screen name, but it might also mean TV.
__________________
"Old age is the most unexpected of all things that can happen to a man" -- Leon Trotsky
NW-Bound is offline   Reply With Quote
Old 06-26-2014, 08:47 AM   #59
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
NW-Bound's Avatar
 
Join Date: Jul 2008
Posts: 19,403
Quote:
Originally Posted by travelover View Post
Re USB charging, I've noticed that the iPad won't charge off a cheap 0.5 or 1.0 amp 12 volt converter. It needs at least 2.0 amps or it won't attempt to charge at all. I'd expect it to charge, but more slowly.

My Nook HD Plus won't charge off any USB except the Nook provided wall wart - evidently it senses non-Nook branded chargers and just deactivates the charging function.
Most likely, the iPad charging starts up and tries to draw 2A. This exceeds the capacity of the little charger, which shuts down to save itself. The "negotiation" for a lower charging current has to be by design, and obviously is not built-in.

I bought a long 12' USB cord to charge my iPhone. It apparently had a miswiring, and when plugged into the phone caused it to announce "Charging is not supported with this accessory".

I thought it was nice that the phone could detect the malfunction but I did not know by what mechanism. Usually when a cable is broken, nothing would happen. I meant to trace the cable to know more, but have not gotten around to it. The USB standard has only 4 wires, but the tiny connector at the phone end has 30 contacts, and this does not make it easy.
__________________
"Old age is the most unexpected of all things that can happen to a man" -- Leon Trotsky
NW-Bound is offline   Reply With Quote
Old 06-26-2014, 10:33 AM   #60
Full time employment: Posting here.
misanman's Avatar
 
Join Date: Apr 2008
Posts: 535
There is much more to USB than one would think. See USB - Wikipedia, the free encyclopedia for some in depth discussion, including power handling and charging.
__________________

__________________
"The best thing about the future is that it happens one day at a time." -- A. Lincoln
misanman is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Saving money on electricity cute fuzzy bunny Other topics 89 02-03-2008 12:50 PM
This one makes the most sense. Electricity is needed. newguy88 Other topics 2 01-24-2008 10:49 AM
Some General Questions Cubitt Hi, I am... 8 12-26-2007 04:36 PM
General questions (while I'm young!) theguyonthecouch Hi, I am... 7 01-25-2007 10:14 AM

 

 
All times are GMT -6. The time now is 04:15 AM.
 
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.