Well, I think there might be a way to make it work with pumped oil. But, as I mentioned before, charge is usually stored on SURFACES. So, if you mixed air with the oil, so it was a stream of bubbles in the oil, that might enable it to carry charge. You could use metal screens that the oil/air mix flowed through to inject/extract the charge.
Jon
My suspicion is that oil isn't a good enough insulator, especially in practice with a pinch of dirt and water in it.
Joe Gwinn
I don't think that will help. That was my specialty, at American Machinist and at Sodick, and I've probably read all of the papers. It's a straighforward capacitor situation until it becomes ionized and permits a spark.
I don't recall any suggestion that the oil dielectric carried a charge itself.
Hmmm. Conductive rubber balls might work, if they're the right density and small enough to pass through the pump. Actually, I don't think they need to be very conductive because of the high voltage and low current. Slightly conductive would be enough.
It would be interesting to know how quickly the charge spreads to the outer surface of the oil column. Too fast to pump it up beforehand, I suspect.
Chris
Interesting thought. It might be possible to create a churning mixture of oil and air.
This could be true. I need to find figures for the resistivity of used transformer oil. I can make sure it's visually clean, but clean room standards won't apply.
Hi Mike,
That's interesting to hear that someone has already tried it. I'd be keen to hear a little more about the details of the design and materials, if you can recall them. There might be a fundamental problem, but it might just be a minor design issue which could be resolved.
Best wishes,
Chris
==========
-jsw
Tweak, Cramolin blue/Caig DeOxit, Stabilant-22A and -22L, and US patent #4696832 are all variants on this theme. End-user products have lots of other ingredients, and some are soap/alcohol/grease mixtures (used to be chlorinated hydrocarbons).
Insulating oils (I've used Shell Diala AX) are inexpensive. Just buy a can. Used oil, presumably, is recycled (re-refined), and won't be easy to locate.
-jsw
How about inverting the generator so you could charge drops of oil and they would fall to the rounded aluminium terminal.
Dan
Never mind
Dan
Do a Google search for "oildag". I used Aquadag to make a conductive coat on fused quartz. Was used inside a Ion Chamber that flew in the early days of the space program.
This may be of interest to some folks. Back in the 60's there was an electronic device for creating an echo/reverb effect for electric guitars and such.
It could replace tape recording devices for a delay effect, at least to some extent. It was generally referred to as an oilcan echo/reverb
Oil-can delay method
An alternative echo system was the so-called "oil-can delay" method, which uses electrostatic rather than electromagnetic recording.[1]
Invented by Ray Lubow, the "oil-can" method uses a rotating disc made of anodized aluminium, the surface of which is coated with a suspension of carbon particles. An AC signal is sent to a conductive neoprene "wiper", which transfers the high impedance charge to the disc. As the particles pass by the wiper, they act as thousands of tiny capacitors, holding a small part of the charge. A second wiper reads this representation of the signal, and sends it on to a voltage amplifier, where it is mixed with the original source. To protect the charge held in each capacitor and to lubricate the entire assembly, the disc runs inside a sealed can with enough of a special oil (Union Carbide UCON lb65) to assure that an even coating is applied as it spins.
The effect resembles an echo, but the whimsical nature of the storage medium causes variations in the sound that can be heard as a vibrato effect. Some early models featured control circuitry designed to feed the output of the read wiper to the write head, causing a reverberant effect as well.
Many different companies marketed these devices under various names. Fender sold the Dimension IV, the Variable Delay, the Echo-Reverb I, II, and III, and included an oil can in their Special Effects box. Gibson sold the GA-4RE from
1965-7. Ray Lubow himself sold many different versions under the Tel-Ray/Morley brand, starting out in the early sixties with the Ad-n-echo, and eventually producing the Echo-ver-brato, the Electrostatic Delay Line, and many others into the eighties.
The Technology of Oil Can Delays Updated 7/1/02
Copyright 1999-2002 R.G. Keen. All Rights Reserved.
Before digital delays, before analog bucket brigade delays, there was an effects technology that subbed in for tape delays that was portable and relatively easy to use for floor mounted items. This was the rotating oil can delay, and here's how it works.
Everyone is familiar with magnetic storage - you move a substrate containing magnetizable particles past a recording head that has an alternating magnetic field in it. The magnetic field polarizes the magnetic direction of the particles on the substrate and an "image" of the magnetic field alternations is thereby stored in the particles. Reading is the reverse - you run the substrate past a pickup head with many turns of hair-thin wire and the magnetic field in the particles causes a voltage to be induced in the coil of wire, reading the info that was recorded.
There are usually "dual" operations for all magnetic and electronic operations, interchanging electric field for magnetic field and capacitors for inductors. This is no exception. If you put charge into a capacitor, it holds the resulting voltage, a crude form of storage. If you have many incredibly tiny capacitors, you can start making a fairly good representation of a varying voltage. This is in fact the way bucket brigade delay chips work.
There is another way to do electrical field storage. Insulating materials can be given an electric charge, as we all know. Just wear rubber soled shoes and walk across pile carpeting on a dry winter day, then touch a doorknob. The motion of the shoes across the carpet stored a charge on the shoes (and then you) that was expressed visibly and audibly when you touched the doorknob.
In a similar way, if we have a fine brush of conductive wires, and arrange an insulating belt to be moved past, just touching the brush, we can put a large AC voltage on the brush and some of the electric field will be captured on the surface of the belt. Since the belt is an insulator, the charge can't go anywhere, so the electrical charge forms a replica of the voltage on the brush. Each tiny area of insulating surface is in fact acting like a micro-miniature capacitor, storing the value of the voltage from the brush at the instant the brush moved away from it, just like the magnetic particles in a tape machine store a replica of the magnetic field from the record head.
The tiny voltage-carrying capacitors are carried off as the insulating belt moves. The voltage would eventually leak off into the air if we let it. We can instead choose to keep it in a dry environment for a while, and "read" it later with a very high impedance amplifier. It turns out that vacuum tubes are ideal for both the writing (at high voltage) and reading (very high impedance) of such capacitive storage, and indeed the first oil can delays were tube based. Later as semiconductor technology got better, transistor and FET read and write amplifiers were made for the oil can delays.
So why the oil? What's that do? Remember that business about leaking into the air? The oil provides a sealable insulating layer over the insulating belt so the charge is trapped inside and has a hard time leaking into the air. The brushes reach right through it to put in/take out charge, and the voltage is protected from leaking away.
The oil is the center of a controversy - the original oil is reputed to be a hazardous material, carinogenic, etc. Is it? Maybe. The best insulating oils available at the time the oil can delays were designed were transformer insulating/cooling oils. These were definitely polychlorinated biphenyl based - the same "PCB's" that are now banned from all use as containing deadly dioxins. The only question is whether the oil can delay makers used that stuff or something else entirely.
If you're restoring an oil can delay that is now dry, what oil do you use? I've heard of using mineral oil from a pharmacy, Singer brand sewing machine oil, even 20 weight motor oil, all said to work to some degree. However, the reports have been decidedly mixed.
I recently stumbled onto the Tel-Ray page
The principals in the Tel-Ray page have now confirmed some of my guesses, and have graciously extended the info a great deal. From the patents, it is clear that the original oil can delays were just as I guessed, capacitive storage devices. However, the second and third patents delve further into the lubricating medium. It seems that by carefully dinking with the lubricating/insulating oil and doping it with various things to get conducting particles spread out in the oil, you can make for a higher signal level stored in the rotating capacitor, and hence better signal recovery, lower noise, and all-round better performance.
Zak Izbinsky, Richard Bills and Jamie Ray dug out the detailed info, as displayed at the Tel-Ray site. The "real stuff" replacement oil for the oilcan effects is Union Carbide "Ucon" LB-65 oil. It is not carcinogenic, and not PCB oil.
This is the exact same substance as was originally used by Tel-Ray in the 60's as specified on the third patent. It is still available through Union Carbide/DOW and is reputed to be only $200 a gallon. ... GAK!!!
However, the guys at Tel-Ray have helped out. They bought a supply and will parcel out just enough for your oil can for about $25. Check them out.
The second method
I've also come across a second method for "oil can" delays. I put the quotes in because it doesn't use any oil. I got a Vox Echo-Reverb model V807 recently. It had a typical oil can delay... until I looked further. There's no oil, but not only that, it looks like there never was any. Multiple spring contacts are held against a rotating disc in a machined aluminum housing with a counterbalancing spring mechanism to keep them all just touching. It looks like this one is intended to get around the Tel-Ray patents. I'll know more when I get the bugs fixed and get it running.
R.G.
Interesting. Reminds me of a Wimshurst machine a little.
Chris
Thanks for all the interesting answers. My gut reaction is that this concep t wouldn't work easily. It's not clear to me if it's possible to readily tr ansfer charge to the bulk of the oil, or if the charge would spread to the outside of the oil column too quickly to be carried to the top. The resisti vity of the oil might also be a problem.
Having said that, I would still like to build an electrostatic machine whic h uses a fluid to convey the charge. It would be novel. If anyone has furth er thoughts or experience, please let me know.
Just now I had the idea of using particles conveyed by a gas. Powder fire e xtinguisher style. I need to think that one through. Metal particles would be like sandblasting and would probably destroy the machine, but some other powder might work.
Chris
Yeah, like ice pellets. The charge transfer between small ice pellets (caught in an updraft) and larger ice pellets (too heavy to move upward) is (the, a?) cause of lightning. There's a charge-segregation at the surface of ice (which is why ice is slippery), that lies at the heart of the phenomenon.
Hi Chris, If I were you, I'd post some of the questions raised over in sci.physics and alt.sci.physics. They will have an answer about oil and charge carrying capacity. And a whole lot more.
Mikek
Are you talking about "flow batteries" or something else entirely?
replying to Christopher Tidy, Brian wrote: Chris it is amazing that you reached the same conclusion I did, that oil could replace the charge belt. In a conventional Van De Graaff generator, the lower end of the charge belt is exposed to a static charge leaking onto the belt, from a series of sharp needles. The upper end works the same way, but in reverse - the charges leak off the charge belt, and onto another row of needles. So. if you replace the charge belt with oil pumped upward into a cavity at the top with that needle thing again, I think it would work. I have heard, that Johnson's Baby Oil, which is a mineral oil, has very high insulative properties, and would work well as a charge pump?
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