I would like a help with an experiment. I would like to make two objects attract and/or repel each other with electrostatic phenomenon, using arduino and two objects of any kind (ie it doesn't have to be a conductor). I don't want to make it with friction or other mechanical way, just pure electronics. In essence, it would make one object positively ionized, and another negatively ionized, so in the end, they would attract each other. I was thinking about a transformator with large ratio, and it would produce a large voltage, maybe million volts, so it will make electrons move towards/away from transformator, making object ionized. Any suggestions?
charlieamer:
Sorry for a bad description, I've edited the main post, with better description
No you haven't. WHAT are you trying to do, specifically. Certainly you aren't just throwing out a wild-ass idea. You must have a specific goal and requirement in mind. What is it?
Essentially, two ionized objects attracting/repelling each other. Ionized meaning it would lack electrons, or it would have excess of them, doesn't matter if it is iron, or any other material.
It is going to be a bit difficult to get a DC high voltage via electronics versus something like a van de Graaf generator, but it can be done. Do you know what a voltage multiplier is? It is a configuration of diodes and capacitors, you feed it AC and it multiplies voltage. You can start with a transformer to step up the voltage to a hundred or so volts, then follow that with a voltage multiplier. Still, a bit difficult to get millions of volts DC in this way.
It is going to be a bit difficult to get a DC high voltage via electronics versus something like a van de Graaf generator, but it can be done. Do you know what a voltage multiplier is? It is a configuration of diodes and capacitors, you feed it AC and it multiplies voltage. You can start with a transformer to step up the voltage to a hundred or so volts, then follow that with a voltage multiplier. Still, a bit difficult to get millions of volts DC in this way.
Maybe I shouldn't go with DC anyway ... so theoretically, if I had a metal ball on one side, at some small distance (like 1cm), and if connect positive multiplier on one ball, negative multiplier on the other, it is possible that thay would attract each other ? Or one would simply statically discharge to the other (like a lightning).
Charlie, Lookup Leyden Jar and read the cautions. Building up enough charge to move, even small, objects can get lethal real quick; and you don't sound like you have much high voltage experience/knowledge.
If you are going to mess about with high voltage generation, then at least current limit the output (mod to multipliers attached) or you may just become a recipient of a Darwin award and your Arduino will get a honorary mention as well.
charlieamer:
Essentially, two ionized objects attracting/repelling each other. Ionized meaning it would lack electrons, or it would have excess of them, doesn't matter if it is iron, or any other material.
That's not "ionized", that's "charged".
Ionized mean the atoms have been torn apart into electrons and positive ions, and you
really don't want that as ionized gases conduct and leak away electrostatic charge.
The only practical ways to separate charge are induction machines like Wimshurst
and Van der Graff generators, although the Kelvin water-drop generator is rather cool
too.
You could have an Arduino control the motor of a VdG generator I suppose,
but you'd have to protect it from any high voltage discharges.
Now, in general, it is difficult to demonstrate electrostatic effects using conventional electronics. You run into too many practical details like: semiconductors stop working. Insulation on wires isn't thick enough to avoid breakdowns. The length of wire needed to get the number of turns in the transformer secondary has a resistance that is overwhelming at the scaled currents involved...
This is why electrostatic generators like Van de Graff, Wimshurst, or Dirod, look so much different than conventional electronics.
You can get "some" high voltage electronics that is unlikely to kill you: CCFL inverters (get them while they still exist!), "Ion Generators", Geiger counter power supplies, HeNe Laser power supplies, and so on. Typically these will generate up to a couple of thousand volts, which MIGHT be enough to show some effects. They're probably about as controllable from an Arduino as a house-lamp (not very.)
"A couple thousand volts" is not much by electrostatics standards; you've seen the lovely spark gaps - air has a breakdown voltage of about 30000 V/cm. You could presumably control the motor of a mechanical electrostatic generator.
There are all manner of folk experimenting with electrostatics and publishing info on the web. I really want to make a wimshurst-like machine out of CD blanks (and other people have done it!)
A lot of electrostatic publications (even Moore) are pretty weak on "quantitative" information. Let's try some calculations.
Columb's law says F = kq1q2/r^2 Force is proportional to total charge and inverse square distance apart.
So, for a force of 1g between charges 1cm apart
.0098 = 9e9q1q2/1e-4 (9e9 is "Columb's constant")
q1q2 = .00981e4/9e9 = 1.1e-8
or for equal and opposite charges, q1=-q2= 1e-4 C.
So we need enough voltage to push 1e-4 C of charges within 1cm of each other. Approximately. It's sorta like charging a capacitor. So, q=CV, and V = q/C
But what's "C" for our charges, 1cm apart? Capacitance is k2A/d Where A is the plate area and d is the distance between them. For practical capacitors, d is typically MUCH smaller than 1cm. Let's give our hypothetical capacitor a capacitance of 10pF. (There is also the capacitance of an isolated sphere (4piepsilon0*R), which wikipedia says is about 20pF for a 20cm van de Graff sphere. So 10pf is probably "close"; off by no more than a couple orders of magnitude
So we have: 1e-4 = 10e-12 * V or V = 10e6V - 10 million volts!
So you can see that the forces involved tend to be very small. That's why electoscopes have leaves made of very thin foil (or gold leaf!) And that's why capacitors don't usually crush themselves...
The 1960(!) World-book encyclopedia had an ion-based rocket engine that hooked an automotive ignition coil with a car battery to a series of pointed rods on the end of a wire. The spark would ionize the air and the positive rod would push against the negative air, giving a little pulse.
At least it was supposed to work like that. Mine never worked, probably because I used a charger instaed of a battery and my primary current was probably pretty weak.
Ion engines are very weak when you consider the force in Newtons. Most are less than one Newton.
They are interesting because they have a very high specific impulse compared to chemical rockets. If you have the time, they are worth it.
