On Sat, 17 Dec 2005 19:32:34 UTC, Sawney Beane
wrote:

When he asked if my tape was steel, I caught on. I had read
somewhere about the signal voltage in rails. That made it worse
because now I couldn't honestly claim ignorance. If anything could
have made the situation more embarrassing, it was to realize I had
started explaining about my invisible friends, Click and Clack, who
had told me to do it.

Do that round here and you'll get more than embarrassed - more like
several hundred volts!

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

On Sat, 17 Dec 2005, TKM wrote:

"Car Talk" is a syndicated radio show in which the Tappet Brothers,
Click and Clack, answer questions about automotive mechanics.

No, it's an NPR radio show in which those two buffoons give reliably
incorrect car advice in between drunken-bum guffaws at their own dumb
jokes.

Well, they did one good thing at least. I met my a woman via their web
site who later became my wife -- some seven years ago now.

Congratulations. Serendipity is a wonderful thing. Click & Clack are still
morons.

"Sawney Beane" wrote in message
...
"Daniel J. Stern" wrote:

On Fri, 16 Dec 2005, Sawney Beane wrote:

"Car Talk" is a syndicated radio show in which the Tappet Brothers,
Click and Clack, answer questions about automotive mechanics.

No, it's an NPR radio show in which those two buffoons give reliably
incorrect car advice in between drunken-bum guffaws at their own dumb
jokes.

I have not found their advice or their brain teasers to be reliably
incorrect. That's why they've taken me in so many times.

Our RR gage came from the width of Roman chariots? (I wrongly
called the width the wheelbase.) The evidence for the myth is that
ruts in the Roman pavement coming out of a stone quarry are as far
apart as modern rails. Saying that was the width of chariots is
like saying jeeps and humvees have the same width as each other and
as eighteen-wheelers.

Maybe each of the early railroad builders used a different Roman
chariot as his gage, and that's why there were so many widths.
They may have been relatives of Click and Clack.

The outside measurement of modern rails is very close to five feet.
I think the original specificaton, in the days of wooden rails,
was for wheels five feet apart at the outside. Wheels and rails
evolved, but new wheels had to fit old rails and new rails had to
fit old wheels. I think that evolution is why the outside
measurement is slightly different from five feet nowadays.

In the US, the most widely used gage was 4' 8 1/2" measured between the
*inside* faces of the rails. This was chosen because most of the early
locomotives were brought over from England, and that was the gage used
there.

Some other gages were used for specialty service, such as mining and
logging. When railroads started interchanging, they had to standardize and
they chose the most common gage. So for the US and Canada, it has been 4' 8
1/2" now for over a hundred years.

daestrom

"Sawney Beane" wrote in message
...
Ioannis wrote:


Your are giving the previous poster reasons to do some serious damage,
particularly if he tries it with a Chinese "CE certified" fluorescent
chord
luminaire!

Never mind what the police will think if they see a guy in the dark
swinging
a fluorescent tube:

"What are you doing there?"

"I'm trying to observe the stroboscopic effect..."

"The WHAT?!"

"You know, when the light goes on and off at 120 Hz, and the phosphors
have
this persistence, see, and you can...by rotating FAST the lamp..."

"Arrest him. He is dangerous"...


"Car Talk" is a syndicated radio show in which the Tappet Brothers,
Click and Clack, answer questions about automotive mechanics. Each
week they read a brain teaser. One week they gave the number of
inches between railroad rails in America and asked how that had
become the standard gage.

There are different parts of a rail to measure from, so I took a
steel tape to measure the track alongside the municipal parking
lot. While I was there, the crossing arms came down and traffic
backed up and no train came.


Big grin!!! The crossing arms are triggered by oncoming trains by shorting
the two rails together and completing a circuit. You did the same thing
with your steel tape (it isn't very much current, just a ma or two).

I watched a front-end loader clearing snow a few years ago in a nearby town.
He wanted to cross the road often to dump the snow on the other side, but
traffic was always a problem for him. Well, he was working across a
railroad track that serviced a small factory and had the usual red lights
and crossing arms. When he was ready to cross the road, he lowered the
bucket down to touch the rails. Bingo!, the lights would flash, the arms
would drop and traffic came to a stop. He'd lift the bucket, cross the road
and dump, and return while the crossing arms were finishing their cycle and
rising back up. He had learned to 'work the system'. But I don't think CSX
approves of such chicanery.

daestrom

"daestrom" wrote in message
...
[snip]

Big grin!!! The crossing arms are triggered by oncoming trains by
shorting
the two rails together and completing a circuit. You did the same thing
with your steel tape (it isn't very much current, just a ma or two).

I watched a front-end loader clearing snow a few years ago in a nearby
town.
He wanted to cross the road often to dump the snow on the other side, but
traffic was always a problem for him. Well, he was working across a
railroad track that serviced a small factory and had the usual red lights
and crossing arms. When he was ready to cross the road, he lowered the
bucket down to touch the rails. Bingo!, the lights would flash, the arms
would drop and traffic came to a stop. He'd lift the bucket, cross the
road
and dump, and return while the crossing arms were finishing their cycle
and
rising back up. He had learned to 'work the system'. But I don't think
CSX
approves of such chicanery.

When I was a teenager, the local railroad used a much more primitive system:

S1-------------Bars-------------S2

Oncoming train would trip switch S1 (or S2) and the bars would lower.
Leaving train would trip switch S2 (or S1) and the bars would go up.

Taking long walks on the railroad tracks was one of my favorite activities
in the summer, so one day I discovered S1. After I pressed it with my foot,
I knew it was some sort of switch, but didn't know exactly that it was S1,
until walking back I saw a heap of stopped cars at the crossing, the drivers
yelling at the the railroad crossing attendant, who was running for some
strange reason towards the opposite side of where I was coming from.

He was of course going to trip the opposite switch, so that the bars would
go up.

On first thought, a funny connundrum. On second thought, a potentially _very
dangerous_ situation, because, IF, while S1 was tripped, a REAL train came
and tripped S2, you can imagine what would've ensued.

Naughty kid :-)

daestrom
--
Ioannis
http://ioannis.virtualcomposer2000.com/
Eventually, _everything_ is understandable

Bob Eager wrote:

On Sat, 17 Dec 2005 19:32:34 UTC, Sawney Beane
wrote:

When he asked if my tape was steel, I caught on. I had read
somewhere about the signal voltage in rails. That made it worse
because now I couldn't honestly claim ignorance. If anything could
have made the situation more embarrassing, it was to realize I had
started explaining about my invisible friends, Click and Clack, who
had told me to do it.

Do that round here and you'll get more than embarrassed - more like
several hundred volts!

I've read that even where rails carry traction voltage, they can
still carry signal voltage. It has something to do with impedance,
but I haven't read how it works.

daestrom wrote:

"Sawney Beane" wrote in message
...

Our RR gage came from the width of Roman chariots? (I wrongly
called the width the wheelbase.) The evidence for the myth is that
ruts in the Roman pavement coming out of a stone quarry are as far
apart as modern rails. Saying that was the width of chariots is
like saying jeeps and humvees have the same width as each other and
as eighteen-wheelers.

Maybe each of the early railroad builders used a different Roman
chariot as his gage, and that's why there were so many widths.
They may have been relatives of Click and Clack.

The outside measurement of modern rails is very close to five feet.
I think the original specificaton, in the days of wooden rails,
was for wheels five feet apart at the outside. Wheels and rails
evolved, but new wheels had to fit old rails and new rails had to
fit old wheels. I think that evolution is why the outside
measurement is slightly different from five feet nowadays.

In the US, the most widely used gage was 4' 8 1/2" measured between the
*inside* faces of the rails.

Now you know why I had to go back and measure again: I got confused
between inside, outside, and center-to-center.

This was chosen because most of the early
locomotives were brought over from England, and that was the gage used
there.

Two locomotives were brought from England in 1829. They were too
heavy for American tracks. In England, Robert Stephenson
demonstrated the Rocket in 1829. In America, Peter Cooper
demonstrated the Tom Thumb in 1830. Robert Stephenson and Company
built the Stevens, now known as the John Bull, for the Camden and
Amboy RR. It went into service in 1831. It's the earliest
surviving steam locomotive, and it has the 4' 8.5" gage.

Not many locomotives were imported. American locomotives were
lighter than English ones and rode American rails better because
the frames were inboard of the wheels.

This page tells where Stephenson got his gauge:
http://www.straightdope.com/columns/000218.html

In the part of England where Stephenson worked, wagons averaged
about five feet because that was the approximate width of two
horses' asses. He laid his rails five feet apart, outside. They
were two inches wide, which put them 4' 8" apart, inside. For
practical reasons he widened it another half inch. I think it had
something to do with flanges and binding.


Some other gages were used for specialty service, such as mining and
logging. When railroads started interchanging, they had to standardize and
they chose the most common gage. So for the US and Canada, it has been 4' 8
1/2" now for over a hundred years.

daestrom

The Federal Government said the gage of the Transcontinental
Railroad would be 4' 8.5". That became the national standard in
the 1880s.

"Sawney Beane" wrote in message
...
Bob Eager wrote:

On Sat, 17 Dec 2005 19:32:34 UTC, Sawney Beane
wrote:

When he asked if my tape was steel, I caught on. I had read
somewhere about the signal voltage in rails. That made it worse
because now I couldn't honestly claim ignorance. If anything could
have made the situation more embarrassing, it was to realize I had
started explaining about my invisible friends, Click and Clack, who
had told me to do it.

Do that round here and you'll get more than embarrassed - more like
several hundred volts!

I've read that even where rails carry traction voltage, they can
still carry signal voltage. It has something to do with impedance,
but I haven't read how it works.

Traction power is carried between the normal rails and a third rail. Never
done just using the two normal rails. So the normal rails only make up one
half of the power circuit. The crossing gate signal is between the rails.

Block signaling is done with an AC signal, transmitted down the rails to the
next signal station. If the next station doesn't receive it (because it's
shorted out by a piece of rolling stock), that signal changes to 'red'/stop
status and transmitts a different AC signal to the next block, which will
display 'yellow'/approach. That's an example mind you. There are about as
many different signaling conventions/circuits as there are railroads.

daestrom

In message , Andrew Gabriel
writes
BTW, here's a nice experiment you can carry out to observe this effect
in a fluorescent lamp. Take a lamp firmly fixed to a long cord (such as
a car service/inspection lamp), and go out into a large dark area (e.g.
outside at night) where there are no objects for many feet in any
direction. Switch the lamp on, and swing it round and round over your
head on the end of the cord. As it passes in front of you each time,
you will see the stroboscopic effect of the different colour components
which make up the white light, and in particular you will notice how
they are all out of phase with each other, with some of the phosphor
components having much longer persistance than others. Obviously be
careful here -- if you manage to hurl a car inspection lamp through
your neighbour's window, don't come crying to me...

Hmm. I just tried this with a dual lamp 8' fixture and it disintegrated
when I got up to approximately 120rpm. It's made a real mess of the
patio.

--
Asa Rimmer.

In message , Sawney Beane
writes
There are different parts of a rail to measure from, so I took a steel
tape to measure the track alongside the municipal parking lot. While I
was there, the crossing arms came down and traffic backed up and no
train came.

I guess the crossing might detect the trains approach when the rails are
shunted. By a metal measuring tape for instance?

--
Clive Mitchell
http:/www.bigclive.com

In message ich.edu,
Daniel J. Stern writes
Congratulations. Serendipity is a wonderful thing. Click & Clack are
still morons.

Bitter, bitter, bitter. Just because the "Daniel Stern automotive
lighting show" got rejected for being excessively technical and
alienating all the "dude" listeners because it continually bashed blue
tinted headlights.

--
Clive Mitchell
http:/www.bigclive.com

In message ,
TKM writes
Well, you've probably figured out that your steel tape completed a
circuit between the two rails within a "block" (an electrically
isolated stretch of rails that controls a set of signals). The circuit
is powered by batteries, but I've forgotten the battery voltage.
However, it's not enough to cause electrocution should you straddle the
rails with bare feet. If you look at the rail joints, you will see a
braided wire fastened to each side so the circuit is continuous and
reliable. The system has been used for many years and is standard in
the U.S. Today, there's probably a line to a computer somewhere that
indicates which blocks are active (indicating the presence of a train
or a fault. Maybe that's what brought the railroad truck and its
hostile occupant to check you out.

Now I'm getting evil thoughts about a little black box with two flying
leads that powers itself from the sense voltage and obligingly provides
a quick shunt every hour or so.

Hmm, a bridge rectifier for polarity independence, a darlington for the
shunt and a PIC12 for simplicity.

--
Clive Mitchell
http:/www.bigclive.com

In message , Bob Eager
writes
Do that round here and you'll get more than embarrassed - more like
several hundred volts!

Or 25,000v if you measure the height to the overhead lines. (Just
500vDC for trams though.)

I've just been out measuring the height of a 500kV power pylon. For
some odd reason the measuring tape exploded. I'm going to take it back
and complain to the DIY store tomorrow.

--
Clive Mitchell
http:/www.bigclive.com

In message 1134944455.694231@athnrd02, Ioannis
writes
On first thought, a funny connundrum. On second thought, a potentially
_very dangerous_ situation, because, IF, while S1 was tripped, a REAL
train came and tripped S2, you can imagine what would've ensued.

If it's a dual rail system then there are separate switches on each
track that have overlaid control on the signals.

--
Clive Mitchell
http:/www.bigclive.com

"Clive Mitchell" wrote in message
...

In message 1134944455.694231@athnrd02, Ioannis
writes
On first thought, a funny connundrum. On second thought, a potentially
_very dangerous_ situation, because, IF, while S1 was tripped, a REAL
train came and tripped S2, you can imagine what would've ensued.

If it's a dual rail system then there are separate switches on each
track that have overlaid control on the signals.

No Clive. I remember the setup. One fixed box approximately 1-2 kilometers
away from the bars, and the same for the opposite direction.

Of course that was 26 years ago. I expect things to have changed by today,
some.

--
Clive Mitchell
--
I.N. Galidakis --- http://ioannis.virtualcomposer2000.com/

In message , Clive Mitchell
writes
In message , Andrew Gabriel
writes
BTW, here's a nice experiment you can carry out to observe this effect
in a fluorescent lamp. Take a lamp firmly fixed to a long cord (such
as a car service/inspection lamp), and go out into a large dark area
(e.g. outside at night) where there are no objects for many feet in
any direction. Switch the lamp on, and swing it round and round over
your head on the end of the cord. As it passes in front of you each
time, you will see the stroboscopic effect of the different colour
components which make up the white light, and in particular you will
notice how they are all out of phase with each other, with some of the
phosphor components having much longer persistance than others.
Obviously be careful here -- if you manage to hurl a car inspection
lamp through your neighbour's window, don't come crying to me...

Hmm. I just tried this with a dual lamp 8' fixture and it
disintegrated when I got up to approximately 120rpm. It's made a real
mess of the patio.


You failed the Darth Vader test then

--
geoff

In message , raden
writes
You failed the Darth Vader test then

Yeah. I wonder how many innocent 4' tubes have died during that test.


"Vvvvit, Vvvvvvvvit" POP.... tinkle clatter.

(Particularly those ones with the coloured plastic sleeve!)

--
Clive Mitchell
http:/www.bigclive.com

On Thu, 22 Dec 2005, Clive Mitchell wrote:

You failed the Darth Vader test then

Yeah. I wonder how many innocent 4' tubes have died during that test.
"Vvvvit, Vvvvvvvvit" POP.... tinkle clatter.

(Particularly those ones with the coloured plastic sleeve!)

....and those being wielded after having been filled with petrol and set
alight by a couple of brainless idjits in Hemel Hempstead, Herts.
http://news.bbc.co.uk/1/hi/england/b...ts/4575291.stm

Palindr?me wrote:

Andy Hall wrote:
On 28 Nov 2005 12:42:50 GMT, (Andrew
Gabriel) wrote:


In article ,
"David Lee" writes:

Clive Mitchell wrote...

Subsequently my mum foolishly gave me a battery and torch lamp to play
with and it all went wrong from there.

I wonder how I managed to survive! My grandparents had a drawer full of
mains plugs and sockets that they used to give me to play with as a toddler.
That was fine but, sometime between the ages of 5 and 10, I gleefully
discovered a similar stash in my father's workshop but together with lamps
and cable!

Snap!
My grandfather had a box full of mains lampholders, bulbs, cables,
plugs, etc, and I played with these, connecting them up in series
and parallel whenever we visited them, and observed effects of
different wattage bulbs in series, etc. I would guess this was when
I was between 7 and 10 years old (he died when I was 10). I don't
ever recall giving myself an electric shock in the process.



Likewise.

I had access to a similar stash at about 4 and was given a ball of
string and a screwdriver to wire them up with. I was using a
soldering iron at about 8 or 9 and going on my own to places like
Henry's in London to buy components at about 10. I still have one of
my early Veroboard projects - a timer made using geranium transistors.

I remember fixing an old Bush TV22 obtained from a jumble sale at
about the same time and learned about the concept of live chassis
products.

http://bakelite_world_2001.tripod.co...know/id48.html




Don't forget GW Smith's in Lisle Street... I nearly got arrested there
as a teenager -the policeman took some time to convince that I was
really after a wobbulator..


And then you had to explain what a "Wobbulator" was. Were you
building a sweep generator, or just jamming the TV channels? Sigh,
using a varicap just isn't as much fun, is it? ;-)

I have a 1968 Smith's Catalogue in near-mint condition, if anyone wants
to /really/ reminisce.

--
Sue


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida