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Is our group still alive?
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Hi Friends For about three years no more messages came? Is everybody ok?
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good materials to use with latex exercise bands
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Looking for recommendations for bottom and top roller material for use with the cheap 600mm 25mm exercise bands. thanks
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5 photos uploaded
#photo-notice
The following photos have been uploaded to the VDG varia photo album of the [email protected] group. 3810989767_e79ba9d3ee_o.jpeg IMG_0946.jpeg Karoli_Simoni1951.jpeg trumpVDGmeek.jpeg VDG 1 MV Budapest .jpeg By: Antivolt <lyonelb@...>
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23 photos uploaded
#photo-notice
The following photos have been uploaded to the VDG Phywe photo album of the [email protected] group. IMG_2826.jpeg IMG_2828.jpeg IMG_2823.jpeg IMG_2824.jpeg IMG_2825.jpeg IMG_1619.jpeg IMG_1618.jpeg IMG_1617.jpeg IMG_1616.jpeg IMG_1615.jpeg IMG_1611.jpeg IMG_1610.jpeg IMG_1609.jpeg IMG_1608.jpeg IMG_1607.jpeg IMG_1606.jpeg IMG_1605.jpeg IMG_1604.jpeg IMG_1602.jpeg IMG_1601.jpeg IMG_1600.jpeg IMG_1599.jpeg IMG_2803.jpeg By: Antivolt <lyonelb@...>
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Wondering if anyone has taken a chance on a solid state tesla coil, either as a kit or fully assembled. This technology has come a long ways and now seems to generate pretty big sparks comparable to the time-tested spark gap method coils. I use the rule of thumb that the spark length should be around a 1:1 ratio to the secondary coil length. As an example, here's one from Ebay that claims such a ratio but it's so easy to fake pictures these days. It's also only 8 1/4 inches tall. It's very easy to think it's much bigger than it really is. It's pretty expensive for such a small coil. And it's called a DIY kit, so I wonder just how much assembly is required. Is the coil factory wound? Another thing, and this is completely unbelievable, is the claimed average rated power of 250 watts! Looking at the wallwart PS in another listing gives the voltage as 18 volts. It must be a switcher, but I still can't see it producing much more than 4 amps, so that's not even 100 watts. AC 110V/220V DIY SSTC Tesla Coil Music High Power Plasma Horn Speaker Electronic | eBay
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Van de Graaff prime season; where is everybody?
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This is the peak of the season for electrostatics with low humidity and less competing outdoor activities. Where is everybody? Let's have a little noise on this group! Be the first to post (other than moi) in 2020 before the month ends.
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Lichtenberg Figures
https://photos.app.goo.gl/GuKVSEsAgJjQq1Nk7 ( https://photos.app.goo.gl/GuKVSEsAgJjQq1Nk7 ) click on the google photo image when it comes up for a larger version. The top two figures that look like fireworks are from positive discharges and the bottom five are from negative discharges. An aluminum cigar tube was placed open end down on the plastic and a charged pie tin was brought near the cigar tube until a spark discharge occurred. The cigar tube was then removed and the plastic was dusted with baking power. The pie tin had an insulating handle and was charged with a Van de Graaff generator. This is almost exactly how G. C. Lichtenberg did it in 1777 only, he used and electrophorus for charging, different powders for dusting and gum-lac, resin for the plastic surface. I'm now charging a 2 nF salt water cap and discharging it through the same cigar tube placed on 2 mm thick acrylic sheet. I started grounding the cigar tube before I pick it up and discovered that this grounding was causing a smaller second discharge of opposite polarity to the first. These next two photos are with out grounding the cigar tube before removal. Positive on the left and negative on the right. https://photos.app.goo.gl/ooJa3hBvpdrTjsh19 ( https://photos.app.goo.gl/ooJa3hBvpdrTjsh19 ) https://photos.app.goo.gl/eET8rr1S2dCK8fmQA This photo is with grounding the cigar tube before removal. https://photos.app.goo.gl/5MpABG1qwAz7DJTh9 ( https://photos.app.goo.gl/5MpABG1qwAz7DJTh9 ) The small inner ring of the positive discharge is the second negative discharge. The negative discharge on the right, has an inner positive discharge that is almost as large as it is. This is because positive figures are much larger than negative for the same voltage. The following two photos show positive figures over 10 cm in diameter using the 2 nF cap on a 11 x 15.5 cm acrylic block 24 mm thick. The count was about 12 seconds charging time. Assuming the VDG is a constant current source of 4.5 uA (which is only approximate because of leakage at these high voltages) the voltage is about 27 kV. https://photos.app.goo.gl/A8XefrTsjtURstbh6 https://photos.app.goo.gl/WQLipRSz6KdHtPVC7 ( https://photos.app.goo.gl/WQLipRSz6KdHtPVC7 ) This is one of the more “artsy” figures. Positive discharge thru 48 mm diameter metal sphere resting on 2 mm thick acrylic with grounded back plane. After discharge the sphere was accidentally grounded and rolled a little toward the upper left. Blobs of negative discharge can be seen as the sphere rolled. click on image for larger view. https://photos.app.goo.gl/qYZXZoethD3YFVBCA ( https://photos.app.goo.gl/qYZXZoethD3YFVBCA )
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Fun way to puncture a plastic bottle
https://photos.app.goo.gl/SpJTSY4UyBUt5HC6A click on gif to enlarge.
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Lightning screen and HV AC power supply
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Doug, This feeding of an auto spark coil through a fairly large series cap with line voltage AC is new to me. Is the basic idea to just eliminate the expense of a step-down transformer that would normally be used to drive the coil? With the lightning screen, is the front plate glued on? Hank
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All of these are for sale at modest prices. https://www.youtube.com/watch?v=h8qnanrSMkE https://www.youtube.com/user/dr043042/videos Doug
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This was given to me by a retired physics teacher. It's a Science First product and may look here a little bigger than it is. It's 20 inches top to bottom; top terminal 8 inch diameter at the widest point; and only about 8 1/2 inches from the lower edge of terminal to the upper surface of the plastic base. It's certainly not a beanpole which is nice, but it should be able to make a spark as long as 8 1/2 inches. The top terminal is really appealing because my prized Harold Strand 5 inch diameter terminal machine /g/VanDeGraaffGenerators/album?id=146073 produces about 12 inch monster sparks, and this SF one is quite considerably bigger at 8 inches. When received the belt was in awful shape: really gummy and gooey to the touch. This gum residue was even coating both pulleys. Cleaning off the belt and pulleys did not get a trace of voltage out of this poor thing. That was back in humid weather so maybe now it might at least have a feeble response, although I tried the hot air trick on it to counter the humidity. I didn't go any further then to fabricate a brand new belt, but I guess now is a good time. There are certain things about this model that I think mechanically could be done better. It appears as if it has a bit of the flavor of improvised design to it. The top electrode does not seem to have been manufactured for the exact purpose of being coupled with its plastic belt column. Looks to me like it's meant to be fitted to a larger diameter column. The top and bottom halves of the sphere, despite being made with a very nice stepped diameter joint, are permanently joined together. :( Hank _____________________________________________________________________ Both these pictures are from the internet.
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VDG build article
Hi group, some years back I posted a VDG tutorial on instructables.com. Below is the link to that article. https://www.instructables.com/id/Homemade-Van-De-Graaff-Generator/ It contains some good info, hope someone in the group can make use of it. Todd Atwood
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High voltage and electrostatic gizmo builder
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[submitted for Doug by VDG moderator] Doug Johnson here, a long time member of VDG group with many pictures on that site. I have spent many hours experimenting with different materials involved with building the VDG's. Best I have found to date are Nylon bottom roller and Teflon top roller, which gives a negative collector. Belt material is natural gum rubber, BY FAR. Collectors are not the conventional like most use but conductive poly bag material used in anti-static bags, just barely in contact with the belt. Only six machines I have built are left, as Grand Valley U. science dept. has been pilfering some of my toys, i.e. a VDG machine, a Tesla coil, a Wimshurst machine, a VDG (belt-only system), and some other toys. I have many videos on my youtube page [non-monetized]. Please feel free to contact me with any questions you may have. Doug J. dr043042 dr043042 My channel is all about high voltage and electrostatics.
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Welcome to the new Van de Graaff group
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Welcome to the new VDG site at groups.io. I'm the group owner and Derrick will continue as a moderator. A big thanks to Derrick for starting this Yahoogroup almost 16 years ago and helping to make this move possible. The site is being built from scratch by hand, without any automatic transfer services provided by groups.io (now costing $220), so it will take a while to attain its final form. Most of the files, and about a third of the photos are already here, though. The historic message database will be the last component to be restored. Hank
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