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Externet

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Everything posted by Externet

  1. Hi. Mixing two cells in series -one charged, the other not- is not a good idea as the charged one may overheat, or dry out. You would be exceeding its charging recommendation time. Two cells in parallel is not a good idea either, as by any unbalance reason current may pass mostly into one and poorly into the other. Cells in parallel is fine for lead-acid and Lithium-ion, but not for Nickels. So what is the charging current measured? I believe for AAA cells should be under 20mA and the red LED can work just fine. If the charger is really limiting the current, should work equally well with only one cell on the bay. Measure the current! It is the case of a shorted cell put to charge; it should not damage the charger nor affect its companion cell, then a resistor or a short could work equally well. Miguel
  2. Hi. Depends on what the batteries chemistry requiere for charging; constant current or constant voltage, and which type of charger it is. No way a common capacitor can be inserted in place of the missing cell. Measure the current on a bay with 2 cells under charge and place a resistor to obtain the same current in place of the missing cell bay. A light bulb could be used too, and if the charge current is under 20mA; a red led could take its place too, as it would provide ~1.5V drop and handle the current. Miguel
  3. Oooops. Sorry, goofed distracted following the refrigerator word stuck to the request. Get a split airconditioner. Will work for distant rooms as the insulated hoses can be of a good lenght; both have already built-in fans for circulation, and provides both heating and cooling areas. Visit your AC shop for an unwanted one going to the dumpster. Miguel
  4. Hi. A working old refrigerator with interior damages should be available free at any refrigerator repair shop. A good way to use it would be inserting the refrigerator in a polyestirene wall dividing areas from your reptiles and your plants, the heat releasing condenser part to keep warmth in one side; and -door removed- the cooling side for the plants. If its thermostat control is working, you are prerfectly set by just adding a fan to the evaporator cooling side... and defrosting periodically. Miguel
  5. This place needs no Mentos... http://www.scienceexperiment.co.uk/experiments/ Enjoy.
  6. Hello 5614 ..."We're talking about making our own charger here"... -->Yes, apply 4.100v to each cell. If you want to make it 'not-home-style'; pick the chip of choice: http://search.national.com/iphrase/query?query=liion+charger&render=1&categories=Product+Folders ..."I don't think it matters whether it is 4V or 4.2V"... --> Yes, it matters. The voltage has to be the one matching the cell chemistry; If too high; degradation takes place; if too low, will not reach full charge. That is why circuitry inside battery packs are so precise, microcontrolled. ..."I would assume they all have equal resistances"... -->Wrong assumption. Miguel
  7. If 4.1001 V are applied to charge that Li-ion cell, it would be a violation of the manufacturer specifications to charge such cell. There is other chemistries of Li-ion, 4.2000 V is the voltage for those. As the question does not specify which, am answering on the safe side. --->..." I don't see an issue charging in series as long as you have the correct voltage across each cell "... And how will you ensure that on a series connection ? Miguel
  8. I thought NaPalm was sodium palmitate, a blend of sodium and palm oil, no orangy juices there. Miguel
  9. Hi. I was one eye half open, the other not; on midnight TV were showing a hen whose eggs where replaced with goose eggs while being incubated. Did anyone see such report and can explain details? Later, the baby geese were following mom, never near water, and on a different diet. What if hen eggs were incubated with mother goose; would the chicks be drawn to water by mom and drown? Miguel
  10. Each cell must be charged independently by itself. If they are all healthy, can be charged in parallel. To charge, connect a regulated supply of exactly 4.1000 Volts at any current that cells will not get warm with. Miguel
  11. And... how does a fireball happen when there is no oxigen?
  12. 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 deep red with a few drops. Cannot find it now... Does anyone know how to make such a highly concentrated water soluble dye/ink/colorant with simple compounds ? Sort of remembering borax as one ingredient, but not sure after 35 years. Oh, those days with no television, no internet... and plenty of good books to discover ! Thanks, Miguel (YT had a good suggestion using oriental food dyes, but still trying to find the elusive formula; maybe new members at this forum have other clues now.)
  13. Hi. To be able to function, feed the body, perform properly, what differentiates between eating a $1/lb plain beef steak and a $ 8/lb NewYork steak ? And a plain lettuce, compared with the fanciest and pricey one; chicken compared to pheasant; what are the nutritive differences? A common cheap bean, compared to expensive kinds; tilapia fillet compared to yellowfin tuna fillet; peanuts compared to brasilian nuts... Do they really deserve the price because of nutritive content or is it all about taste or nearly only taste ? Miguel
  14. What am unsure of is what you mean by 10 stages... 2 branches of 5 or 2 branches of 10. A similar circuit without one branch would mean 10 stages using 20 diodes; i think. On this one, a single resistor should be at the centre 'in' to function equally on the entire cycle but the 'out' terminal could be tapped without the resistor. For low energy requierements, just use much, much smaller capacitors; still will yield same tension with barely inrush current. Miguel
  15. I believe it does; Half cycle is handled by one branch of the circuit, the other half on the other branch, equivalent to a continuos voltage applied in the amount of the RMS value of the AC. The actual charge voltage in the capacitors will be more like the peak voltage of the AC, but the charge time is independent from voltage and will not be affected. Miguel
  16. I would say 10 stages x resistance in Ohms x capacity in Farads = time in seconds to reach 66% of final tension. Miguel
  17. You are missing some promising possibilities... Remove engine and all extra iron and : -Install a sail; it will be smooth sailing; -Cut off floor pan, get sturdy shoes and do the jogging; will save a lot of money otherwise spent on the gym; -Install a wind-up motor, charge the spring every morning; do not use music-box type, the tune will get annoying soon; -Tie a zillion helium balloons, then the weed wacker motor will make you fly; -Connect the exhaust pipe of the old engine to the exhaust pipe of your new car; then by feeding the fumes, the old engine will turn in reverse with the pressure and convert the fumes into pure air and gasoline. It's ecological and makes some money too. For sure there is more ways, just think a little ! Miguel
  18. Hi Gene. I sent you a private message but unsure if I did it right. Miguel externet @ inorbit . com
  19. Hi. I have somewhere among my spider webs, a gadget that I have never used, it is smaller than a pack of cigarettes, divided in two sections. One is a transmitter and the other a receiver. The transmitter half is meant to be attached to a kid (or a briefcase) and you keep the receiver in your pocket. If the distance between the halves exceeds ~5 metres, reception is lost and the alarm sounds. When not in use, one half attaches to the other turning both off. Miguel
  20. Hi. Why arcing ? All bodies will have the same charge polarity in order to be repelled. The rings would have to be suspended with strings, the cylinder vertical - Is that the way you envision? Miguel
  21. Hi. I have some idea of how they work, but never inspected one closely nor played with one. Question; what do you think would happen if bits and pieces of plastic are fed to it instead of sugar? Would it produce some "plastic wool" ? -Similar to fiberglass ?- (am not joking) Miguel
  22. Or the fuse in the current meter already let the smoke out in another previous goofing... Miguel
  23. Hi. The French had a plausible intention, but goofed big time with the development of the metric decimal system; not because of the metre, but because left the work unfinished and we are stuck to a senseless not decimal system in too many fields. Being the worst of all, the time measurement. A second should had been 1/100 of a minute; A minute should had been 1/100 of an hour; an hour should had been 1/10 of a day as example. The non decimal system is the one that is in need of a mission-impossible redefinition. And who came up with latitude and longitude not being decimal? Go spank those. Leave the metre alone and better think on fixing these really stupid non-decimal systems. Redefining the decimal metre based of a non-decimal second is a very wrong idea. If the British want to keep their liquid ounces, furlongs and grains, let them mess with their stuff as the urinal capacity of king such and such being the gallon standard.
  24. Hi Swansont. I said that just because someone may say the kinetic energy from the projectile dissipated into heat at the spring -or rubber- and will not move the car much because of the energy loss. As in another extreme example, the bumper with a layer of play-dough to avoid the bounce and drop after; someone can say the dough converted energy to heat in the deformation. JustStuit: Thanks for your calculations. If the projectile bounces back and still has some speed after the impact, isn't because did not deliver all of its kinetic energy ? and thus, the car will not move as much as in the case of the projectile that did not have energy left after the impact because it delivered all of it to the car ? Miguel
  25. Hi all. I do not see why the bounced projectile speed matters for the response, but if a figure is preferred as clarification, just say the projectile bounces back at 30% of the speed it had before impact. And some other detail if needed later; assume there is no thermal loss in the impact onto the springy or rubber bumper (the rubber -nor the projectile- will not heat up upon collision by deformation) Miguel
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