Does anyone know what this is?

[barge sara]

Are there any ancient electrical engineers out there who might recognise this?

 

 

It stands about 12 inches high, disc is calibrated in 400 segments but no units given.

 

Made by Seimens Bros & Co. London.

Edited February 22, 2010 by barge sara

[luctor et emergo]

Is it a controller for a vey early railway set?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

coat...

[NB Willawaw]

What is the knob connected to beneath the card - is it rotating a coil within another wound coil which is shown at the bottom of the picture ?

[Boatgypsy]

Are there any ancient electrical engineers out there who might recognise this?

 

 

It stands about 12 inches high, disc is calibrated in 400 segments but no units given.

 

Made by Seimens Bros & Co. London.

It looks like it might be an old potentiometer. Does that help?

[Roger Gunkel]

Could it be a tuning coil for some sort of early radio system>

 

Roger

[Albion]

Are there any ancient electrical engineers out there who might recognise this?

 

 

It stands about 12 inches high, disc is calibrated in 400 segments but no units given.

 

Made by Seimens Bros & Co. London.

 

If the dial moves an iron core relative to the coil could it be some sort of variable inductance? But, I'm no expert so it's only a guess.

Roger

[Kez]

an disconnected electrodynamometer i think. we've got one in our 'box-of-old-stuff'

[NB Willawaw]

I was getting there, I was getting there

 

Very good

 

http://physics.kenyon.edu/EarlyApparatus/E...ynamometer.html

[barge sara]

an disconnected electrodynamometer i think. we've got one in our 'box-of-old-stuff'

 

I was getting there, I was getting there

 

Very good

 

http://physics.kenyon.edu/EarlyApparatus/E...ynamometer.html

 

That seems to be the one - thank you very much for all suggestions.

The large coil can rotate just enough to move the front pointer between to stops about half an inch apart, and the knob appears to apply a force to resist the turning force via a light coil spring under the dial. Presumably the reading on the disc can then be related to the electric current?

 

Just one of several odd bits of kit found in my Dad's study after he died last year.

[twocvbloke]

an disconnected electrodynamometer i think. we've got one in our 'box-of-old-stuff'

 

oooooh, say that again....

[Kez]

oooooh, say that again....

 

Its sad isn't it? I shouldn't know that, I should be out hot-wiring cars or playing computer games...

[twocvbloke]

Its sad isn't it? I shouldn't know that, I should be out hot-wiring cars or playing computer games...

 

Nah, only those that lack confidence do that...

[WotEver]

So what's the knob for?

 

Is that design a 'peak measuring' instrument and the knob is for resetting it to zero?

 

Tony

 

Edit to say no (Google was my friend).

 

If I've understood the below correctly, the knob was turned to zero the coil, and the current was then measured from the rotation required. Here's another picture

 

Siemens Bros., London

In an electrodynamometer the magnetic field is provided by a current carrying coil instead of a permanent magnet. It was invented in 1845 by Wilhelm Weber (1804-1891), Professor of Physics at Leipzig and Göttingen. This is operated in the null mode, i.e., the fiber suspending the rotating coil is turned so as to bring the coil back to its rest position, the current then being read from the angle of rotation of the fiber. This was a secondary standard for current measurement until the 1920s when it was replaced by the more convenient direct reading meter patented by Edward Weston.

References: John T. Stock and Denys Vaughn, The Development of Instruments to Measure Current, Science Museum, 1983, p.39-40; Gustav Wiedemann, "Die Lehre von der Electricitat, 1895, pp. 64-66; Whipple Museum Catalogue 8: Electrical and Magnetic Instruments, 1991, No. 151.

Edited February 23, 2010 by WotEver

[John Orentas]

Looks a little different to the normal type but generally called a "Variac".. A variable transformer produced as a test/ development device.. Powered from a mains typ. 230 vac the output is selected on the big dial..

 

Just a simple device for obtaining a low current selectable voltage, often permanently connected to a voltmeter for a more accurate reference.

[WotEver]

Looks a little different to the normal type but generally called a "Variac".. .

Nope, it's definitely an electrodynamometer - otherwise known as an ammeter

[twocvbloke]

Nope, it's definitely an electrodynamometer - otherwise known as an ammeter

 

Didn't have the same effect that time...