|
|||||||
|
|
|
|||||
|
|
|||||||
![[the prototype wimshurst]](w1side.gif)
This has to be the single most difficult, and time-consuming project that I've yet to tackle in my high-voltage pursuits.
Built during my Sophomore year, it was the completion of a very long struggle, learning a great deal along the way. Hence, the "prototype". I am currently nearly finished with a much improved device, using 12" plexiglass discs. The prototype was built simply to prove that I could build an influence generator. I spent as little money on it as possible, basically using only what I had available to me in my high school's metals tech room, what I had laying around, and what i could get from friends/relatives.
Using a pair of 10" bakelite 78rpm records, I began to fashion this contraption in my mind. I abandoned the want to make it motor-driven rather swiftly, settling on a more classic hand-cranked approach. The only part I was really worried about was how I was going to make the discharge terminals movable, for obvious reasons. This I solved in a simplistic manner, by running my two HV buss rods through a section of 1/2" thick plexiglass, and drilling a second set of holes down into the plastic, so a rod set into the open holes would rest on top of the HV carrier, making contact. With a little bending of the rods supporting the terminals themselves, I set them up so that they might be easily adjusted by swiveling in thier bases.
The whole thing was mounted on a piece of particle board, With two upright supports being the only connection to the wood. These were held in place with a set of metal braces I made. Originally I tried to use a section of wooden dowel to support the two discs, which both rotated freely on the same fixed axel, as I afraid that if I used steel it would present a problem. But i had to dispense with the wood; it flexed a little too much, and the discs touched eachother at their top edge, while remaining over 1/4" apart at the bottom edges. Steel rod was neccesarily substituted, and doesn't seem to present much of a problem to the operation.
Each disc is cemented onto a lexan boss turned on the lathe, with three layers of thin rubber gasket sandwiched in between the discs and the bosses. The bosses were center-bored to rotate feely on a 1/4" shaft. When the fixed steel axel was set accross the two upright supports, the discs sat level enough that they wouldn't progress at all when spun. I happily dispensed with the springs I had been trying to use to compress the discs towards one another, along with the collection of washers I had added. All of that squeezing and slipping added an unwanted amount of resistance.
Each disc boss had a pulley-like groove set into its narrowest part, for the drive belt to rest in. The bosses were driven by belt from a set of larger pulleys fixed to a shaft running through the uprights near thier base. For the belts, I used a pair of extra-long heavy-duty rubber bands, which I kind of regret as they aren't very sturdy, and while I haven't had one break on me, they do produce copious amounts of fine red powdered rubber. It sticks to everything and I KNOW that it has to be hurting the generator output. So that the discs spin in opposite directions, one belt makes a figure-eight while the other does not. A simple crank is attached to the end of the pulley drive shaft, though I made it attach by threading part of it on, so it can be removed easily. This allows for the possibility of rigging a motor drive for it, as I did once... ...thing squeaked like a banshee.
![[The motor drive]](w1mtr.gif)
Each neutralizer is adjustable, locking onto the same axel that the bosses turn on with plastic shaft collars and set screws (both made by me). I used 1/16" copper rod to form the supports for the blades, and the blades themselves were fashioned from the serrated metal strips that make the cutting edge on seran-wrap, wax paper, or aluminum foil boxes. The tip nearest the edge of the disc on each blade was coated in silicone sealant, to try to reduce the leakage I saw there.
![[The w1, from an angle above]](W1UP.GIF)
I kept the high voltage collectors as simple as I could... ...perhaps too simple. They are just a section of 1/4" steel rod bent into a "U" shape, with the rod continuing out of the "U", sort of making an "S", but stopping midway through the bottom horizontal line. They there make a right angle turn, to run through a piece of 1/2" plexiglass that supports them. This plexiglass was mentioned earlier, so I'm not going to describe it again. Each terminal is made from aluminum, one being a large ~3" ball, and the other a double ball terminal, havin 1 ~2.25" ball and a ~1" ball. All the balls were cast by hand, then filed, sanded, and buffed to a high sheen. With that, and no leyden jars, the thing produces sparks about 1.5" long in relative humidity.
Hmm... Did I forget anything? If I did, let me know
eemail: electrophile@juno.com