At that low of frequency, and at the (implied) low current I would be thinking of driving the plates with active devices. I suspect that there are IGBT's that will do the job, and if not I have some VT-4C's in my attic that should be able to stand 3kV on their plates.
Please note that I will have _nothing_ to do with this if you kill somebody. Safety is your responsibility, not mine. If you sue me do it in Kansas*. All of the safety measures that are implied by sticking someone's head between a couple of plates carrying 1kV between them should be observed (or even sticking a dog's or sheep's head in there whilst and at the same time holding onto the animal). In fact, find a few extra safety measures and stick to them, too.
- - - -
My sister lived there for a while. While many of their cultural norms make this agnostic, non-conformist west-coaster gag they do have the refreshing opinion that if you do something stupid with someone else's property it's your mistake to pay for, not McDonald's or my insurance company.
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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
If you don't think it's too dangerous, that's a very bad sign.
You mention 3kV/m with 0.3m plate spacings, which works out to 900V. My latest HV amplifier design does +/-1200V, which would meet those specs, but I think I'll not give you the details! Ahem. Here's a +/-4kV amplifier on eBay ... However I recommend against it in your case,
I want to do some experiments on the effects of HV VLF electric fields on the brain. The frequencies involved are 4Hz upwards and I'd like to use a sine rather than spike waveform. Voltages to be approx 3000V/m upwards (values found during thunderstorms).
The tentative setup would be to feed the AC signal to two large insulated conductive plates, probably around 500mm x 500mm with a separation of at least
300mm, probably quite a bit more. The head would placed between them.
Now, transformers are not esp efficient at 4Hz, but then again I do not need to drive much current (I think). Can anyone suggest what the transformer would look like eg turns, core etc? Suggestions for driving circuit also welcome.
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Dirk
The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
Well, I want sub mA current flow on short circuit, so it shouldn't be too dangerous. I suspect your method might lead to instant lobotomy at best in case of accident.
I suppose I'll have to work out the ballpark capacitance and stuff...
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Dirk
The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
How do you propose exposing the brain to the electrostatic field? The skull and tissues of the scalp will be a pretty good electrostatic screen at those frequencies.
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~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Probably. However, they will not be perfect. I'm interested because I have not seen anything documented on the effects of HV fields, or lack of effects.
I assume that there will still be a polarising effect that extends through the head. Apparently even a few hundred mV applied directly can cause quite noticeable effects.
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Dirk
The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
If the electrodes are exposed, they're dangerous to the touch. You don't believe that? If the electrodes aren't exposed, on account of insulation, most of the electric field ends up being developed across the insulator, and not across the conducting subject matter, the head and brain.
If you want to induce 500uA electrosleep currents in the head, use electrodes: "The electrodes may be saline-gauze sponges over metal plates applied between frontal and occipital locations."
There's also the electrosleep band. "Musically electrosleep assault and dazzle the listener with dueling guitars, cascading keyboards and manic vocals." No electrodes needed... Here's a sample:
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Also, I found this: "I would advise against making your own machine unless you are a very good electrical engineer with a good bio-medical background. Good luck in finding a doctor who won't laugh his narrow- minded, prejudiced, priest-like ass off when you mention this."
Well, as part of the expt I will also be trying VLF modulation of kHz fields.
Because I know about that technology already. Armchair theorists say all kinds of things are not possible, until some experiment shows they are. Then it's a case of "...of course it will work if XXX is taken into account". An ounce of experiment is worth a tonne of theory.
google, electrosleep
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12000 hits
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Dirk
The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
How much is the intrinsic capacitance of 0.2m diameter sphere? How much is the resistivity of human tissues. Evaluate the time constant. Then you can have an idea of the voltage gradient wrt to your frequency.
But I know in my bones, err... preferably in yours, that it'll be almost nothing.
But then, if you do want to induce some real E field, why don't you put the electrodes directly in contact?
I guess Joerg can give you some advice on building a debrainillator...
Well, we have Fred saying how there will be no effect whatsoever, and you implying that it's a suicide machine. Care to elaborate? Bear in mind that electrosleep machines have a very long and safe history when it comes to actually passing sub mA current through the head.
You think the electric field alone will be more dangerous?
And I *do* know how to build amplifiers that will pump out kV and kW - it's just that I don't actually want high power and complexity. Hence the transformer question.
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Dirk
The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
Not if they are powered at 900V with a short circuit current not exceeding 1mA That's why I don't think your amp is of much use to me. And it is why I asked a question about transformers at VLF. Certainly not efficient, but I don't want efficiency. The voltage is only going to insulated electrodes with a capacitance in the pF so the current should be negligible at sub 10Hz frequencies.
Probably. And it will *probably* have no effect, but it's worth trying as part of the expt. The other part of the expt involves modulating a kHz kV waveform with VLF.
No, been there, done that.
Actually, I do have a doctor friend who doesn't laugh at such things. However, this has nothing whatsoever to do with medicine.
--
Dirk
The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
Well, I got a very respectable jolt once from a car coil that I had hooked to a toy train transformer: 19 VAC, 60 HZ to the primary, and making fun arcs with what came from the secondary, until I got my thumbs on opposite terminals. BZZZZAAAAAAAT!!!
Of course, that had nothing to do with my current mental condition, nope, no brain damage at all, not a bit, nope, nope, nope, nope.....
If he is actually wanting the high electric field inside his flesh, then obviously there will be a problem. Providing he is investigating the effect of the head being placed in a volume of air which has an electric field in it, then he should be fine. I think it would be possible (but tedious) to do this in a way that meets all appliance safety regulations. (e.g. TV sets can cause high electric fields in front of the glass.) I thing that if the plates are insulated behind 6mm of polypropylene (or whatever thickness one is legally supposed to use for the voltage in question), then the electric field in the gap between the plates will hardly be affected by the insulation, (at least for AC fields). Since the dielectric constant of the insulating sheets will be greater than that of air, the insulating sheets will drop less AC voltage than the same thickness of air would.
Actually this idea of applying high voltage AC fields to the head sounds a bit like the electrostatic headphones I built, adapted from from some in a '70s Wireless World magazine. I think I had about 500Vp-p (1kVp-p differential) of audio on each set of perforated plates (which were just
100mm square plates of single sided FR4 with lots of 3mm holes, and etched sections around the edge), with a piece of kitchen cling-film stretched over spacers in between the plates, the cling-film was charged to about 1kV DC, through a resistor of a few tens of Megs made out of many resistors in series so that several could fail quite safely. I connected several high voltage ceramic capacitors in series with each amplifier output (each one rated for more than the supply voltage), with a DC bias resistor from the headphone connector to ground. The amplifier output stages were common emitter with resistive loads so the resistors would stop it from killing me anyway even if all of the many series connected caps were to fail. The AC signal current from the amplifier was not dangerous, it just tickled if you touched it, since it could only provide enough current to drive the couple of hundred pF of the headphones.
The headphones sounded really good. With the voltage of my amplifier they weren't quite loud enough, and had a tendency to collect dust inside, so they needed frequent disassembly and cleaning.
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