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'[EE] Anyone know anything about galvanometers?'
2012\05\21@161903 by William Couture

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Someone I know picked this up, but can't tell if it is complete, or
how to put the
pieces together.

Clues?

http://imgur.com/a/U7V0d

Thanks,
  Bill


-- Psst...  Hey, you... Buddy...  Want a kitten?  straycatblues.petfinder.org

2012\05\21@164041 by Spehro Pefhany

picon face
At 04:19 PM 5/21/2012, you wrote:
>Someone I know picked this up, but can't tell if it is complete, or
>how to put the
>pieces together.
>
>Clues?
>
>http://imgur.com/a/U7V0d
>
>Thanks,
>    Bill

Does this help?

http://www.abdn.ac.uk/~nph126/BSHS%20Display/BestofBritish/slides/ABDNP200975a02.html

Is there a mirror visible through the window?

2012\05\21@165339 by John Ferrell

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flavicon
face
The Galvanometer is a null detection device usually used in a Wheatstone Bridge circuit. The balanced bridge is detected at zero volts and therefore does not load the circuit under test. There is generally a light source involved to project a shadow of the indicator on the screen. You may not be able to detect the motion of the movement without significant magnification or by projecting its shadow. The adjustment screws are to level the device and the protective cover (Can?) protects the movement from drafts. There should be some meas of clamping the movement in transit to protect it from damage. Although it is obviously very fragile, all that I have seen are not to difficult to repair. The lubricant I use on pivots is kerosine, only as much as you can carry on the tip of a sewing needle.

Try to help it find a good home, they don't make them any more... I disposed of mine because I did not want them to wind up with an uncertain fate in my estate!

On 5/21/2012 4:19 PM, William Couture wrote:
{Quote hidden}

-- John Ferrell W8CCW
“During times of universal deceit,
  Telling the TRUTH becomes a revolutionary act”
     George Orwell

2012\05\22@001229 by John Gardner

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I know galvanometers were the detectors used in trans-Atlantic
telegraphy circa 1860. Don't have a reference handy, but imagine
the reactance of  an uncompensated 3000 km cable would limit
bandwidth to a few WPM...  That first connection failed after a
few weeks, and was not restored until after the Civil War.

Probably just as well; @ 300 baud GB might well have decided
to jump in,,,  :


'[EE] Anyone know anything about galvanometers?'
2012\06\08@164340 by Barry Gershenfeld
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On Mon, May 21, 2012, John Gardner wrote:

> I know galvanometers were the detectors used in trans-Atlantic
> telegraphy circa 1860. Don't have a reference handy, but imagine
> the reactance of  an uncompensated 3000 km cable would limit
> bandwidth to a few WPM...  That first connection failed after a
> few weeks, and was not restored until after the Civil War.
>

This Wired article could serve as a reference.  The data rate, which they
didn't really like to talk about, was more like one word per minute.  This
guy Whitehouse was something of a crackpot, and hatched the grand notion
that long cable problems could be solved with more voltage.  At 2,000
volts, he shorted it out permanently.

William Thompson developed the mirror galvanometer in response to this
long-cable problem, and when the new one was laid, it was an instant
success.  For a recounting, see:

http://www.wired.com/wired/archive/4.12/ffglass.html?pg=20

For more entertainment, go back one page and read the last paragraph.

If you have been hooked and want to read all about undersea cables, read
the entire article in the printable version, the link to which is found at
the top of each page

2012\06\08@190738 by John Gardner

picon face
!  Thanks...

Jac

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