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Externet

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Everything posted by Externet

  1. Hi everyone. From what I remember, the highest electronegativity differential between two metals, the larger the voltage obtainable in a battery when those metals are used as its anode and cathode. Did I remember well? Using easy to get and cheap materials; as aluminium, copper, iron, carbon, lead, zinc... which two would yield the highest potential ¿lead and copper? Am trying to build a simple seawater cell to activate an ultrasonic beacon at expense of the electrodes. An electronic circuit transforms the cell output to a higher voltage for circuit operation. Current capability is proportional to electrodes area. Thanks, Miguel
  2. Hi. How many millions of years has our sun been burning ?... All that mass reduction being consumed to radiate energy for that lenght of time, has reduced its gravitational force attraction, and keeps happening, is it? Then, its pull is not a constant ! For the earth to maintain orbit on a decreasing solar gravity pull, the orbit diameter has to continuosly diminish accordingly, does it ? Or the orbiting speed slowing, does it? Miguel
  3. Hmmmm. Naming as a compass the points on the drawing to have some reference... Being N&S an independent voltage source from W&E ; the positive S is such only respect to negative N. The positive S has no potential respect to either W & E and no arcing should occur in that direction. Miguel
  4. Hi. If I understand the graphic, the high voltage sources being paired in diagonals, the double arcing will occur in cross fashion, as sources are independent. Very good question, I suspect there will be collision of the arcs. No attraction, no repulsion, just crossing paths sharing a central point. Start edit, adding : <Re-thinking,... each arc creates a magnetic field which would affect the crossing point position of each other by forced deflection, and the polarity would determine if one arc passes above or under the other on direct current. Then there would be repulsion or attraction due to magnetic and not to electric fields. If alternating current, there would be a alternating cross path above and under. A similar behavior is an oscilloscope in x/y mode. Vertical defflection plates do not affect horizontal deflection plates electrically.> end edit Perfectly controlled conditions to do the experiment may be unstable. Please come back with observations. Another similar situation could be a neon tube cross, with independently powered straight arms. Miguel
  5. Hi. Once I browsed a ~400+ page book of formulas with the detailed procedures to manufacture hundreds of real generic commercial products, I remember was over $2000 and well worth them. Examples: formula and process to make brake fluid, detergent, artificial pigment, fly-sticky paper, deodorant, chlorine for pools from seawater... all kinds of things... It is not a household remedies book. Cannot remember the publisher, author, title. Any clues ? Thanks, Miguel
  6. Hi. A refrigerator compressor makes the best of all easy to get vacuum pumps. It really sucks ! You will be able to distill at room temperature. Many are discarded in good working condition. Get one, the size of choice, it is simple to plug and runs nearly silent and u$ually free. Keep its rubber mounts. Miguel
  7. Hi. It is a common suggestion to get rid of ice on a windshield by pouring cold water on instead of warm; there has to be a relation to the behavior Am from Barcelona too, and I pretend to know something... sometimes. Miguel ¿Why do my posts show a checkmark on rating? I have not done anything bad !...
  8. Hi. No.- water vapour, water, heat, cold, did not cause any alteration to the tinting; neither was affected by window cleaners nor showed any aging. At edges where the deposited film remained thicker, it was clearly observable micro puddling areas and dried beading. Was not water based. Imagine wetting an almost horizontal glass, water runs off but the lower edge forms a thicker non-running bead by whatever cohesion reasons. This was no Mickeymouse film job at all. Am very sure it was a liquid applied onto the glass surface. I had a conversation with the person that developed the product and there was not much magic in it; he just had his successful formula and made a side living out of it. The reason the glass had to be removed and laid flat to dry the ink was exactly because was so thin and fluid, that could not be applied to vertical surfaces as most of it would drip and make a big mess. Most customers were reluctant to have the glass dismantled from their cars, but the guy was soooo good, experienced and careful not to miss a clip or lose a screw and keep alignments that I had zero problems, zero complains about the job. The only similar process I am aware of, is gradual tinting in "degradé" done to eyewear lenses, were the lenses are repeatedly vertically dipped onto a solution, at gradually different dephts to dye the upper portion of the lenses darker. Seen it done. Miguel
  9. Hello. 20 years ago, I had my car windows glass tinted overseas by a guy that removed the glass from doors, applied an ink to the inner surfaces by dipping -or spilling onto- (masking the exterior surface); let 24 hours to dry in a dust-free place and reinstalled them. The somewhat involved job result was a superb, yes, superb hard surface with no visual distortion, scratch resistant, UV filtering and unable to peel off. There was half a dozen hue choices in smoke, grey, clear, goldish, bluish, greenish... Several years later, by accident, a bottle of alcohol leaked inside my car parked under the sun and some areas of the ink "crackled" with the fumes. Does anyone knows how to prepare such product? Or ever heard of such process ? Thanks, Miguel [edited: changed the word "crackeled" to the appropiate "crackled" to accurately describe the effect of solvent fumes]
  10. Hello, thanks for responding. Good question; I did not consider this dye to be too dangerous as was to be prepared by young experimenters with common sense in that book from the fifties/sixties; but realize the world has changed a lot since and it has to be taken in account. If there is a choice, would like to avoid caustic, poisonous and restricted access chemicals, maybe the regular compounds those complete hobby experimenter's chemical sets used to have many years ago, could be good, not the lean kits available of today. Cannot really answer the question properly, any suggestions or options would be fine. It may be something similar to fluoresceine, used to trace underground aquifers and their surfacing points; and believe fish and plants are not harmed from it. From the little I remember, it was a liquid as a result of some simple process of mixing a few chemicals. Miguel
  11. Hello. As a kid in the sixties I read on a chemistry and physics experimenter's book written for young readers, a simple process to home make something like what is now named rhodamine, capable of dying a whole pool water red with a few drops. Cannot find it now... Does anyone know how to make such a highly concentrated dye/ink/colorant with simple compounds ? Sort of remembering borax as one ingredient, but not sure after 45 years. Oh, those days with no television, no internet... and plenty of good books to discover ! Thanks, Miguel
  12. Hi Matt. That has nothing to do with my question. What is the shape of the focus on a catenary reflector? It should not be a point. Is it a line, is it a circle, or...? Miguel
  13. Hello. It's been over 30 years since my days at the university and have trouble thinking... I believe a catenary reflector has a focal area -locus?- instead of a focus point as a parabolic reflector has. Is it a circle ? The intention is to place a pipe of the same section at the locus of a catenary reflector trough, to be insolated and boil water circulating in it. The center of the locus must be centered between the ends of the catenary. The catenary lenght is 4 feet. What would be the correct catenary span or depth? Thanks, Miguel
  14. Same as the net force acting on the water. Will not be buoyant, will not sink. Miguel
  15. Hi. Stolen from http://groups-beta.google.com/group/sci.chem/browse_thread/thread/e953efcde574ddf/dfadde77d600eed7 : The reason that stainless steels are corrosion resistant, even though they consist mainly of iron, is because they contain a minimum of 12% chromium, usually along with some other metals. Ordinary iron and steel alloys rust quickly because atomic iron is much smaller than oxides formed by interacting with atmospheric oxygen and/or oxygen dissolved in water. The oxides formed during rusting create a loose layer that flakes away, exposing fresh metal to the corrosion. Chromium, along with other metals ( such as nickel ), are added to stainless steel alloys to help improve physical propeties and corrosion resistance. The chromium in the stainless steel combines with oxygen, forming a very thin passive film of chromium-containing oxides. The sizes of chromium atoms and their oxides are similar, so they bind together on the surface of the metal, producing a thin oxide layer only a few atoms thick. If the surface is rubbed or damaged and the passive film is broken in air or water, more chromium oxides will immediately form and recover the exposed metal substrate surface, protecting it from further oxidative corrosion. Note that the oxide film is not physically strong, it just forms rapidly, and weakly adheres to the alloy, thus protecting the metal below from further corrosion. It can be disrupted and displaced easily by abrasion, so many common stainless steels aren't suitable for corrosive situations where the surface is continually swept, and special alloys, with other elements are used.. The passive film requires oxygen to self-repair, so stainless steels can have poor corrosion resistance in situations where there is limited oxygen or other elements or species will compete with the oxygen. The smelly active sulphur species in garlic and onions; the volatile selenides in garlic, cabagge, and broccili; and also the chlorides in salty water will all attack and destroy the passive film of most stainless steels more quickly than the film can be repaired in a low oxygen environment. Some of the smelly compounds will bind to your hands ( onto proteins, lipids etc ) and will become non-volatile ( non-smelly ), but the number of binding sites is limited, hence any excess of smellies results in smelly hands. By binding to the metals in the stainless steel bar, the unbound smelly compounds on the surface your hands are transformed into non-volatile ( and thus non-smelly) compounds and complexes on the surface of the stainless. The new surface layer, which is weakly adhering and fragile, will be continuously abraded off by the active rubbing of the bar and replaced by oxides using oxygen from air or water. For many stainless steel items, especially those in contact with chemicals or water, passivating metal finishing processes are applied ( such as treatment with nitric acid ) when fabrication is complete. This ensures they start life with a good, thick layer of oxide. Otherwise corrosion may start in any crevices, scratches, or heat-affected areas ( welding ), and unprotective deposits ( eg smutty black sulphur layers ) may form in low oxygen environments, such as water. I hope the above is more understandable, and addresses your questions. (by Bruce Hamilton)
  16. Hi. At least this will be good for science fiction... The earth and our moon are in a very delicate and precise balance of speed and interacting gravity maintaining their position. In theory¿? any force applied to the moon can change its orbit a given amount. Assumming feasability of assembling a large enough upside down propulsion rocket on the visible side of our moon (or a smaller one for long enough time) and pushing it out of orbit until it is gone, gone...spiraling out no longer on earth's orbit. Yes, many catastrophic consequences implied here, but keep the imagination on. Doing the same with Titan, if a convenient atmosphere and water and other amenities are found there, bring it aiming precisely to start orbiting the earth as replacement. Well, another place to overpopulate and pollute would be available. With proper technology, time and calculus; is there any tiny chance for this to be not fiction some day ? Miguel
  17. I have deleted my own poorly expressed post, where I should had said the atomic clocks are less related to earth's rotation now after the Ninetyeast ridge quake. Miguel
  18. Yes, you are lighter at equator; by two reasons; the increased distance from the center of earth gravity and the centrifugal force. http://www.madsci.org/posts/archives/mar97/857469722.Ph.q.html http://www.madsci.org/posts/archives/mar97/857469722.Ph.r.html What I don't get is if an object on top of a scale at equator determines the force of gravity there or the force of gravity less the centrifugal force. By figures from a post above, 9.78 = G(eq) minus 0.0337 In other words, the weight of a body at the equator does not obey only to the gravity constant there but also the centrifugal force; then the pure gravity constant figure measured at the equator is inexact because the centrifugal force was not taken in account.... I think... Miguel
  19. Hello everyone... Sound propagates in air at 340m/s by the sucessive compression/expansion of the highly compresible gas medium due to soundwaves; ¿ How do solids propagate sound with such diminished compressibility ? ¿ What is the typical range of sound progagation speed in plain soils ? Much faster ? And further ? and with less attenuation ? ¿ Are earthquakes detected by microphony or motion transducers or both ? There was once a web site and group dedicated to sense underground noises, I would appreciate any clues to locate it. Thanks, Miguel
  20. Hi. Trying to learn on the subject, found some good literature and principles of the process but I have this doubt: -Assuming plain water and not extreme vacuum ; the vacuum pump creates 24 inches of mercury, enough heat supplied to the liquid. The vapor starts filling the vacuum above the liquid surface, decreasing the vacuum reading or not? In other words, the vacuum pump must operate constantly and not only to achieve an initial amount? If the vacuum has to suction all the time to maintain said 24"Hg , why is an internal condenser used inside the distillation chamber ? The condensation could be collected at the vacuum pump discharge. Thanks for the light. Miguel
  21. Hi. From my poor understanding, a cesium clock could then be made to work also at other characteristic transition frequencies ? Hello atinymonkey. The link referred does not work, received this : " Invalid Thread specified. If you followed a valid link, please notify the webmaster " ¿Can you please confirm it was properly copied? Miguel
  22. Hello. Can someone direct me where to look for a list of the characteristic frequency, vibration or oscillation of the elements? From atomic clocks information I was able to collect figures for only 3: Rubidium = 6.834,682,612 GHz Cesium = 9.192,631,770 GHz Hydrogen = 1.420,...,... GHz Am looking for the rest, or whatever is known. Thanks, Miguel
  23. Hi everyone. As I am not a thermodynamics guy, but an electronics guy, I beg for your asistance on this forum on my lack of heat transfer thinking. Planning to drill a ~100m deep well in my backyard, it is supposed to reach well beyond a stable ~20°C thermal layer; circulate water trough a long 2" U shaped polyethilene pipe to provide home cooling in ~30°C summers and help warming in ~0°C winters : A convection geothermal heat pump. What are the effects of the water velocity on amount-of-heat transfer ? From analogies on internal combustion engines, the faster the flow the greater the heat transfer - that is why racing engines have high flow coolant pumps- . On the other side, a slow flow speed allows the circulating water to reach the stable temperature and deliver all its potential temperature. What is more convenient ? A small mass flowing at a higher temperature differential or a larger mass flowing at a lesser temperature differential ? Seems to my ignorance that any will work equally, as the amount-of-heat would by Q=mass x (t2-t1) ; leaving good convection radiators, low losses, proper insulation of pipes, system efficiency to determine its effectivity. Is the ideal flow speed the one that will allow the flow to reach within a couple of degrees to ensure there will be heat transfer at all times? Thanks, Miguel
  24. Hello YT2095 Would had been a nice try if some results were obtained. The aperture is narrow, yes. Solar stills with plain flat glass do produce a respectable amount of drinking water with the same temperature differential. No bottlenecks there. The intention is to find a distilling application recycling the zero cost PET disposable beverage bottles, for the third or fourth world to get some drinking water using many of these contraptions. The bottom sun exposed bottle is flat flack, the necks mating has a condensate collection ring and aquarium hose outlet. All that seems fine. Ideas to make the vapors rise to the upper bottle are needed. Maybe venting the top bottle as in distilling colums would help by producing a tiny agitation of the water surface ¿? Miguel
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