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VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


twosideddice posted:

That's pretty fascinating. Have you got any links for how one of these engines actually worked? As far as I understand the way turbine engines work, they rely on shooting air out the back of them at high speed, which wouldn't really work on a train. So obviously it's something else and I'm pretty curious.
It is an electric locomotive. It just has its own power plant on board.
Turbine referrers to the fact that the steam rotates a turbine ( sort of like a propeller) instead of pushing a cylinder in a traditional steam engine.

Almost forgot that content:

A rotating current train. It needs three overhead lines. Although some models got around with two lines, by putting a voltage directly on the actual tracks.

VictualSquid has a new favorite as of 18:45 on Jun 28, 2013

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VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


This was the first commercially successful public electric tramway:


If you look closely you notice that there is no pantograph and no third rail.
It was simply supplied with those 160V DC current through the tracks themselves. The uninsulated tracks running through the middle of Berlin.

After too many incidents of people and horses getting electrocuted, they put up a fence and tried to turn off the current on the crossings if no train was nearby.

But there still were various incidents of people and horses getting shocked.
The city youth also found a new hobby of throwing wires between the tracks to watch them spark and melt as a nice cheap firework.

It operated like this for almost 10 Years. Then the pantograph got invented.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


So this is not actually obsolete, it still has some niche uses. But it used to be pretty big and crazy awesome.

There is a piece of technology called a Motor-Generator. It used to be the easiest way to transform DC to AC, AC to DC, AC to AC of a different frequency, and DC to DC of a different Voltage. These days ( since the 80s) this is done electronically.

They are still used for converting extremely high AC power to a different frequency. So the left over ones are big, this one converts 50Hz network power to 16.7 Hz for use on the German railway net. :


A common variant is this:

This looks like three different motors/generators on the same axis. Because that is what it is.
Motor 1 drives the axis using power from the normal net.
Generator 3 generates a small voltage which is used to excite the coils in Generator 2.
Generator 2 generates DC power.

This power is pretty stable and easily controllable by controlling the exciter voltage. It can be made more stable by adding a flywheel which would be replace by a capacitor in a modern setup.


Now one place where you would want controllable high power and voltage DC current is to drive the motors on a train.
So you would send your voltage through that set before sending it to your engines, if you are designing an electric train.

Another somewhat similar quirk was the idea to generate the low voltage needed to run the lights on a train from a generator attached to a empty running wheel. But people very quickly noticed that this was a bad idea.

So if you want to turn on the lights on your train:

A turbine turns in the power plant driving an axis.
This axis goes in a generator to make some current.
The current turns a Motor in a traction substation.
The Motor turns a Generator in the same substation.
The current turns a Motor on a train to turn an axis.*
This Axis creates a current in Generator.
This current excites another Generator to Generate a Power.
This Power turn the motors driving the train.

and if we get really crazy:
This movement turns an undriven wheel on the same train.
This creates Power in a Generator.
Which you use to turn on the lights.

I have heard, that British Rail used those much more even after the had become outdated. So maybe Axeman Jim can supply some better pictures.

* On a modern train there would be a switching power supply here to drive the wheels and the onboard current.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Geoj posted:

But can you use it as a life raft in the event of flooding?




Sun still makes those. I was using one for work until 2 years ago. It even was attached to a semi-dump terminal.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


TotalLossBrain posted:

I am not sure what it really is, but it sure looks like a horrible mechanical Furby face.

It looks like a signal monitor station for TV-Transmitters. It shows the modulation-trapezoid and the TV signal.
The modern ones look almost exactly the same, until digital TV took over.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Have you considered using actual cash money.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Jerry Cotton posted:

What the God drat gently caress are you even talking about?
It means that here in the socialist paradise of Germany if I see an advertising/pricetag of 10, I know that I can put 10 on the counter and walk out with the product. If the shop complains he is committing advertising fraud.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


I remember reading an old engineering thesis where the author included thanks to his girlfriend for writing in the math in a readable way after he typed the text.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Also, when I was in school I learned how to use those in my technical drawing course:

https://en.wikipedia.org/wiki/Lettering_guide
You traced one letter/number after another with your ink-pen. It was surprisingly fast with even a bit of practice.

That intermediate time where most normal text came through computers and printer, but anything unusual was made by hand and then optically copied was quite strange.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Cojawfee posted:

What are the red lines for?
To make it easier to find the correct distance between two letters.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Stencils used to be very popular.
I used one of those through college, it probably still is in some moving box in storage.


Back in those days there were supply stores near colleges and tradeschools with large racks of useful stencils, right next to the crayons for the younger kids.
Starting from the common stuff, like circles or metric screwheads.
Ending with more exotic stuff like NATO symbols or hydraulic logic circuits.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Cojawfee posted:

Electricity and math combined is just great when you get to AC stuff. You know how complex numbers are a + bi? Well, you can't use that because I is current because C is the speed of light. So you use j. But the j also goes in front. So it becomes a + jb. Then when you're figuring out phase angles, you use phi, except for when you use theta, and then sometimes you use both theta and phi because each one represents a phase angle for a different component, but then later on they become the same and you add them together.

And then you specialize in the wrong subfield and nobody talks about current I because the current density j is much more useful. And you still stick with j for the imaginary number.

VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Fun fact: the good TI calculators used the same Motorola 68k cpu that also powered the Sega Genesis, Commodore Amiga, Atari ST and early Apple Macs.

I actually had a teacher who used to work on analog computers back in the SU. According to him, those were generally more accurate then computations with 8 bit numbers and cheaper/faster then computation with larger word-sizes.

That reminds me, anybody remember the octet? Back in ancient times byte referred to what is called a word these days, and was machine dependent. So telecoms and network people decided to call 8-bits an octet.

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VictualSquid
Feb 29, 2012

Gently enveloping the target with indiscriminate love.


Kwyndig posted:

I remember reading about an engineer who set his alarm up so it could only be disabled by a keypad in another room by entering today's date on it.

Nothing stopping you from going back to bed though.

The android app thread used to have recommendations for several different apps that do that. In the thread title.

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