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Question Identification required please

2 months 1 week ago #41505 by Technician Q
I found this under the workbench in the preproom. I think it must be something to do with investigating the resistance of different materials but one of my predecessors made a lot of stuff and was a hoarder so I don't actually know if it is complete, unfinished, missing a bit or broken!

Any ideas? Thanks.

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2 months 1 week ago #41506 by SteveKeys
Hmmm... Interesting one. First thing I thought was a piece of kit for graphing equipotential which is in the SHAP A Level Physics course. Then I noticed the 4mm plugs and the diagram. That Voltmeter on the schematic looks very much like it's in series not parallel. If this is the case it could be absolutely anything you want it to be for how well it will work!!

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2 months 1 week ago #41508 by Baldilocks
Interesting TQ. At first sight I thought that it might be a bin filler but looking a bit closer I thought that it could be an UFO - Unidentifiable Frowing Object.

Any chance of a close-up of the diagram? Is it copper, any idea what the black bit is?

Ian

“Do not believe everything you read on the Internet.” -Abraham Lincoln

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2 months 1 week ago #41509 by Baldilocks
Interesting TQ. At first sight I thought that it might be a bin filler but looking a bit closer I thought that it could be an UFO - Unidentifiable Frowing Object.

Any chance of a close-up of the diagram? Is it copper, any idea what the black bit is?

Ian

“Do not believe everything you read on the Internet.” -Abraham Lincoln

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2 months 1 week ago #41510 by D.B.Ferguson
My guess (as suggested earlier):
It looks like a home made (or lower quality) version of : www.personal.psu.edu/ref7/apparatus/2002...n/PJ%20Ouseph-IL.htm
You may need more carbon coated paper (Teledeltos). There are more modern methods using this paper.
A close up of the circuit diagram could confirm this,

Technicians: providing solutions and more.

David Ferguson B.Sc.

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2 months 6 days ago #41512 by Technician Q
Hope the close up is clear enough. The orange bit looks very much like copper to me and the black is conductive paper. Having wired it up the reading on the voltmeter drops as you move the fly lead away from the bottom red connector until you reach the copper when it drops suddenly to near zero.

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2 months 6 days ago #41514 by D.B.Ferguson
That is as I would have expected.
Place some ordinary paper under neath the conductive paper with a sheet of carbon paper (may need to go to a stationers) with the carbon side on the plain paper.
When done, connect up.
Using the volt meter as a guide press firmly down at regular voltage intervals.
Do this for various points all over the conductive paper.
What is marked on the paper underneath is a plot of equipotentials.
Should look like the plots in a text book!

Technicians: providing solutions and more.

David Ferguson B.Sc.
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2 months 5 days ago #41524 by Technician Q
The conductive paper is stuck down.

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2 months 5 days ago #41529 by D.B.Ferguson
Ahh, I see.
The only thing I can suggest then is to plot voltages as a function of angle and distance.

This could be done without affecting the paper by using a marker ( type may make a difference?).
Concentric circles at fixed distances.
And lines at, say, 10 degree intervals.

Technicians: providing solutions and more.

David Ferguson B.Sc.

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