kelseymh

Google is your friend. Fourth hit.

Nah! Some of us just have too much free time during the winter break ;-/

Definitely, provide that (a) your 800 mah battery supplies the correct voltage (3.6V), and that it has the right contact pattern for your device (modern batteries have more than just +/- contacts, so that the device can monitor the charge, and for doing current-control on recharging).

1) Polishing is a well-known ancient technology, at least 4000 years old (polished Egyptian and Sumerian jewelry). Getting a hard stone (like granite) from a rough surface finish to a fine polish is done with automation today, but can be done by hand, using a series of finer and finer grits mixed with water.Lathes are also at least 3000 years old (1300 BCE Egyptian lathes are known).2) The Nazca lines are not "perfectly straight", although woo merchants love to make that claim. They are certainly straight to the eye at ground level (visible along lengths of a few hundred meters), but show deviations from an ideal path consistent with step-wise surveying. The artwork is _not_ on mountain tops (please cite a reliable source), but rather on the surface of the Atacama desert, a…

1) Polishing is a well-known ancient technology, at least 4000 years old (polished Egyptian and Sumerian jewelry). Getting a hard stone (like granite) from a rough surface finish to a fine polish is done with automation today, but can be done by hand, using a series of finer and finer grits mixed with water.Lathes are also at least 3000 years old (1300 BCE Egyptian lathes are known).2) The Nazca lines are not "perfectly straight", although woo merchants love to make that claim. They are certainly straight to the eye at ground level (visible along lengths of a few hundred meters), but show deviations from an ideal path consistent with step-wise surveying. The artwork is _not_ on mountain tops (please cite a reliable source), but rather on the surface of the Atacama desert, and have survived this long primarily because the desert is extraordinarily dry, and was not part of any major trade routes.3) Nearly all the pyramids need to have "hidden voids" in them, in order to reduce the load borne by flat ceilings of known shafts and chambers (Egyptian technology did not include arches or vaults, just post-and-lintel). We just haven't found most of them. The shape of a pyramid is very simple, an artificial hill. Why would multiple cultures _not_ come up with an "artificial hill" structure as a representation of power or authority?4) Pareidolia is a dangerous game to play. Just because something "looks like" your favorite futuristic technology doesn't mean it is.7) Please provide reliable source citations for your various Antarctic claims, especially for anything "well above freezing."

There are "bidirectional" or "double acting" hinges available, though they seem to be rather pricey (US$15 to $50). With such a hinge, you wouldn't need to do a dual "french door" design, just a side-mounted swinging cat door.In doing this search, I tried "side hinged pet doors", and ran across this:https://www.moorepet-petdoors.com/Saloon-Dog-Door-...It seems expensive to me, but the pictures might inspire you to build your own. In place of actual double-acting hinges (above), you might consider a pivot post (a dowel which extends above and below the door into the frame), maybe with trim magnets to hold the door closed when not in use.

If you're using methanol to clean your circuit boards, then a quick rinse with distilled water (*NOT* tap water! and not deionized water, either) will carry away the methanol, and you can dry with a lint-free wipe.

If you have U.S. "standard" rectangular wall/ceiling registers, made of sheet metal, you can buy magnetic sheets which seal them over extremely well.https://www.amazon.com/Accord-AMAGCOV815-Magnetic-...You can also get large vinyl magnetic sheets and cut them to shape yourself.This method allows you to avoid having to open up the ductwork to install valves, or to access the valve controls via a crawlspace or holes in the ceiling.

And it seems that it has been. Thanks!

You don't seem to have a very clear distinction between different sources of radiation. Electrons are not neutrons. Your "uranium beads" are not neutron sources. They emit electrons (beta particles) which can heat up materials and break chemical bonds. Beta radiation does not cause induced radioactivity.

McMaster-Carr uses "ball detent" (which was my first search attempt) for something entirely different! Namely, the kind of clevis pin that has a little ball near the end to keep it from working loose. It also sells set screws with a similar little ball at the end, which it also calls "ball detents."

McMaster-Carr calls them "dog-leg quick release connectors" (go figure), and says they're also called "snap buttons and tubing buttons." See https://www.mcmaster.com/#button-clips/=171vn6b

[ Sorry for the delay; I've been on vacation and offline... ]Ah, that is much more reassuring! The Crookes tube was invented in the 1870s, so the technology was definitely there. In fact, it was exactly the fact that the apparent beam of light inside was deflected by a magnet which led Thompson to realize that they were little charged particles, and to measure the (negative) sign of that charge.Cloud chambers are definitely within the bounds of that technology (you can make one at home with dry ice and alcohol).Tesla coils and van de Graff generators can produce hundreds of megavolts of potential, which is easily enough to accelerate electrons to produce gamma rays, and to pair-produce.I think you can definitely build a satisfactorily realistic scenario for your story using period techn…

[ Sorry for the delay; I've been on vacation and offline... ]Ah, that is much more reassuring! The Crookes tube was invented in the 1870s, so the technology was definitely there. In fact, it was exactly the fact that the apparent beam of light inside was deflected by a magnet which led Thompson to realize that they were little charged particles, and to measure the (negative) sign of that charge.Cloud chambers are definitely within the bounds of that technology (you can make one at home with dry ice and alcohol).Tesla coils and van de Graff generators can produce hundreds of megavolts of potential, which is easily enough to accelerate electrons to produce gamma rays, and to pair-produce.I think you can definitely build a satisfactorily realistic scenario for your story using period technology. Just don't try building it at home!

You really, REALLY, do not want to do that with any kind of source. If you build a multi-MeV particle accelerator (which is what you will need to get the >> 1 MeV gamma rays needed for pair production), you're going to be dealing very serious shielding issues. The level of your questions imply some lack of expertise in this area, which will lead to non-trivial hazards to yourself and to others.If you want to observe pair production in a cloud chamber, you can get that reasonably well, at a low rate, just from cosmic rays. If I were doing it (the way we did in my undergrad HEP lab about 30 years ago), I'd use a muon hodoscope as a trigger to backlight the cloud chamber and shoot a digital camera image.A hodoscope is a couple of plastic scintillator paddles with photodetectors, pla…

You really, REALLY, do not want to do that with any kind of source. If you build a multi-MeV particle accelerator (which is what you will need to get the >> 1 MeV gamma rays needed for pair production), you're going to be dealing very serious shielding issues. The level of your questions imply some lack of expertise in this area, which will lead to non-trivial hazards to yourself and to others.If you want to observe pair production in a cloud chamber, you can get that reasonably well, at a low rate, just from cosmic rays. If I were doing it (the way we did in my undergrad HEP lab about 30 years ago), I'd use a muon hodoscope as a trigger to backlight the cloud chamber and shoot a digital camera image.A hodoscope is a couple of plastic scintillator paddles with photodetectors, placed vertically, and with a stack of metal (lead or steel) to act as an energy filter. You connect the two (or more) photodetectors in a coincidence circuit. If both the upper and lower ones fire, then you know you have a particle going both in the right direction and with enough energy to do what you want. You can put another sheet of steel below the hodoscope to hep with gamma production.

Bremsstrahlung ("braking radiation" in German) is medium to high energy X-rays produced when electrons are suddenly decelerated. They're the main way that X-ray tubes work: accelerate electrons to high voltage and direct them onto a thin metal foil. The electrons stop, and X-rays come out the other side.You're not going to see electrons, and you're going to have the safely issues of an unshielded X-ray source.

It sounds like, especially from your citation of "1917 materials" is that you want to build a Crookes' tube. This is similar to a CRT, in that the electrons are emitted and accelerated from a cathode, but it doesn't have magnets or electrostatic plates to produce or direct a beam. I would recommend starting with the Wikipedia article, so you can see what one looks like and understand the general principles. You can then follow the links from there to get some guidance on building a simple one.

McMaster-Carr calls them "multidirectional acetal wheels" (https://www.mcmaster.com/#omnidirectional-wheels/). They sell 2-in (5 cm) diameter wheels for $16 each, close to your budget.The ones you found from RobotShop are probably your best deal.You should be able to make an almost trivial adapter using square rod and drilling or milling a 5 mm hole down the axis.

Why don't you built it yourself and see what happens? You are claiming a "balanced seesaw." 1) That means that you have the same mass, as dead weight, on one arm of the seesaw as the total mass of flashlights at the other end.2) That means that when you use your arm to "shake" the deadweight end of the seesaw, you (or whatever magic motor you build) will have to exert the same total force as shaking all the flashlights at once (so ten flashlights = ten times the effort).3) The energy stored by a shake-weight generator (like your flashlights) is much smaller than the energy required to do the shaking. There is a lot of waste involved.Just because you don't believe in math or science is really irrelevant. Reality is what it is, and wishing won't make it any different.

So you're not even interested in wasting your own time on this foolishness, but you want someone else to do it for you? That is certainly, er, "ambitious."

Been there, done that. Doesn't work. The system will come to a stop quickly when the forces on either side balance. It is very easy to fool yourself if you only have a partial understanding of physics, and don't want to go to the trouble of computing something that might prove you wrong.http://www.lhup.edu/~dsimanek/museum/unwork.htm

I'm not sure what you're asking. Such an object would most certainly not "look" the same, if you are talking about actually viewing it, with your eyes, or camera, or whatever. There will be definite distortions because of the high rotational velocity.However, for small objects, its _motion_ under a static gravity field won't be affected its rotation. For small objects, the motion is governed by its center of mass, not by the distribution of that mass. This assumes the gravity field is changing (spatial gradient, not time-varying) slowly enough that tidal effects across the object are negligible. If tidal forces are not negligible, then the rotation will have an effect.