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Old 2nd Jul 2022, 9:39 pm   #1
broadgage
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Default Wimshurst machines.

Many of us will be familiar with these machines whereby extremely high voltages at minute currents may be produced.
Used to demonstrate electrostatic principles in school labs.

But did these machines ever have any real uses ? was there any machine or device that used Dozens of kilovolts at minute currents. Early night vision equipment perhaps.

A large and probably lethal peak current could be obtained from a bank of Leyden jars charged by a wimshurst machine.

Winding the handle would soon become tedious, but an electric motor or large clock work motor could be used.
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Old 2nd Jul 2022, 10:18 pm   #2
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Default Re: Wimshurst machines.

When I was at university, circa 1969, the high voltage lab had a high stability 800kV generator made by the French company SAMES. Externally it was just a big cylinder with the high voltage lead emerging at one end but we were told that it was built on the same principle as the Wimshurst machine. It was used to measure pre-breakdown currents in the nano amp - micro amp range.

I believe that internally the disc of the Wimshurst machine was replaced by a cylinder with a hundred or so segments along the axis, each which was split into several sectors.

I have no idea how many were made or if the technique was used by other manufacturers.

Regards,

Roger
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Old 2nd Jul 2022, 10:36 pm   #3
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Default Re: Wimshurst machines.

There's a liquid version using falling water droplets which works by the same principles, Google 'Kelvin Generator' for details!
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Old 2nd Jul 2022, 10:54 pm   #4
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Default Re: Wimshurst machines.

I have a facsimile volume of the Model Engineer for 1904 which has several illustrated examples of reader's home-constructed X-Ray apparatus which use Wimshurst machines to provide their operating voltages.
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Old 3rd Jul 2022, 6:02 am   #5
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Default Re: Wimshurst machines.

I am not sure if it's a real application, but I saw (I think in the London Science Museum) a gas lighter which had a little Wimshurst machine inside. The trigger spun the disks which generated enough voltage to cause a spark at the business end, thus lighting the gas jet.
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Old 3rd Jul 2022, 9:38 am   #6
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Default Re: Wimshurst machines.

I do remember that at my school the physics staff had a machine that could generate electricity that would pass through multiple people and give you a shock. I think the person at each end had to hold onto a brass tube connected to it and I think it generated pulses. It was quite small but I don't think it had a large rotating disk, I really can't remember.

I would be interested to know what it might have been.
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Old 3rd Jul 2022, 9:55 am   #7
Dave Moll
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Default Re: Wimshurst machines.

The other common static electricity generator was the Van de Graaff generator, which used the friction of a rotating belt to charge up a large metal sphere. Was this what wireman remembers?

For comparison, here is a Wimshurst machine (unfortunately non-functional) I bought at RetroTech in May.
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Old 3rd Jul 2022, 10:09 am   #8
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Default Re: Wimshurst machines.

Quote:
Originally Posted by wireman View Post
I do remember that at my school the physics staff had a machine that could generate electricity that would pass through multiple people and give you a shock. I think the person at each end had to hold onto a brass tube connected to it and I think it generated pulses. It was quite small but I don't think it had a large rotating disk, I really can't remember.

I would be interested to know what it might have been.

It was the Wimshurst machine. My Physics master did the same trick with the class. I opted out since playing regularly with scopes and valve amplifiers I already knew what a shock was like.
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Old 3rd Jul 2022, 10:59 am   #9
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Default Re: Wimshurst machines.

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Originally Posted by barrymagrec View Post
It was the Wimshurst machine. My Physics master did the same trick with the class. I opted out since playing regularly with scopes and valve amplifiers I already knew what a shock was like.
I would have remembered anything large and with an obvious mechanism. I can remember the Van der Graaf setup for example. I wondered if it was something like a victorian electric shock/therapy machine which may or may not have used the same principle.

As a possibility I found this example on the web:

https://collection.sciencemuseumgrou...electrotherapy

If anyone wants to feel and see the effects of static electricity I can recommend a visit here: https://www.mos.org/live-presentations/lightning
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Old 3rd Jul 2022, 11:47 am   #10
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Default Re: Wimshurst machines.

The small item was probably an induction coil. In the 1950's and 60's I remember seeing them in adverts in the papers by a company that used to sell magic tricks (illusions) and jokey things (Ellisdons?).
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Old 3rd Jul 2022, 12:05 pm   #11
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Default Re: Wimshurst machines.

Wasn't a rather large Wimshurst machine demonstrated on Tomorrows World, where a car was driven around the towers? They were checking that the vehicle acted as 'Faraday' cage, in that the lightning strikes hitting the vehicle would disipate safely and not injure the vehicle occupants nor cause the vehicle to malfunction, or even ignite the fuel. I think that they used to do something similar for aircraft. Perhaps other members might remember the tv program.

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Old 3rd Jul 2022, 3:53 pm   #12
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Default Re: Wimshurst machines.

Quote:
Originally Posted by emeritus View Post
The small item was probably an induction coil.
Something like this?

Using the back EMF from a trembler to generate the shocking voltage.
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Old 3rd Jul 2022, 5:54 pm   #13
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Default Re: Wimshurst machines.

I still have my antique 1920 Wimshurt machine in my storage shed. It was working perfectly. I purchased in 1991 as a student from an antique shop in Convent Garden, Central London. I was crazy and paid £230 for it. At the same time, I also bought a new Van der Graff generator from a school scientific supplier. I think I had a thing for high voltage at that time which sowed the seeds of me building solid-state and spark gap tesla coils a few years ago. I also have a 40kV electrostatic volt meter that has only mechanical parts.

The Wimshurst, Toepler-Holtz influence machines were used for x-ray machines. It is possible to generate x-ray using hand cranked wimshurst machine:

https://carlwillis.wordpress.com/200...ranked-x-rays/

Alternatively, a rectifier valve and a small wimshurt machine can be used to generate weak x-ray.

It is possible to buy a mini motorised Wimshurst machine this guy in New Zealand:

http://www.sparkitelectrostatics.com/
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Old 3rd Jul 2022, 6:11 pm   #14
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Default Re: Wimshurst machines.

Well at least my memory has been corrected as it seems that the large lightning units must have been Tesla coils.

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Old 3rd Jul 2022, 6:41 pm   #15
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Default Re: Wimshurst machines.

Hi Dave, a good clean and dry, possibly new foil pads and a good re varnish and you machine should be up and running again

Ed
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Old 3rd Jul 2022, 6:52 pm   #16
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Default Re: Wimshurst machines.

If you're referring to my machine, it also needs a repair or replacement of the front drive belt.
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Old 3rd Jul 2022, 8:25 pm   #17
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Default Re: Wimshurst machines.

I have to claim bragging rights here!

Where I worked we had a Cockcroft-Walton generator. 2.4Mv peak* (yes Megavolts!) for lightning strike simulation on power cables, you certainly weren't holding hands in a circle touching that one.

At school we had that usual trick played on us by the physics teacher, I think he also used the Van de Graaff generator to make the hair stand up on some of the longer haired scuffions.

* we had tiddler unit in another part of the lab (actually more like an aircraft hanger than a lab) but that only went up to 1.2Mv. Meh.
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Old 3rd Jul 2022, 8:40 pm   #18
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Default Re: Wimshurst machines.

I remember our school physics-lab Van de Graaff generator, where the teacher put a piece of furry-skin [supposedly a catskin, more likely rabbit or squirrel] that had been used in an earlier static-charge demonstration where glass and ebonite rods were rubbed vigorously with the skin to generate a static-charge] on the big ball atop the VdeG column, then wound-up the motor.

When the critical static-voltage was reached, the furry-skin twitched around the edges, then levitated itself from the ball, and floated off into the enthralled audience!

The school Wimshurst was used to generate charge to light a six-foot fluorescent tube; we had competitions to see who could best crank the handle to get the brightest glow.
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Old 3rd Jul 2022, 8:41 pm   #19
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Default Re: Wimshurst machines.

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I think he also used the Van de Graaff generator to make the hair stand up on some of the longer haired scuffions.
As our school was co-ed and the boys weren't allowed hair long enough for this demonstration, our teacher used the girls instead.
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Old 4th Jul 2022, 5:18 am   #20
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Default Re: Wimshurst machines.

I recall Wimshurst machines in an old science fiction story. A large Wimshurst machine was driven by cycle type pedals and the output used to propel a very small spacecraft by means of an ion rocket. Not an enclosed vessel, operator had to wear a pressure suit.

Not a practical means of travel, more of a futuristic sport or competition.
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