Externet

Hi. Do this: connect the speakers from your stereo together; (no amplifier at all involved) gently push/tap one cone and observe the other following nearly the same motion. With sound, the motion is much less, but happens. The sound becomes an electrical signal , goes trough the wires and becomes again vibration at the other speaker. Miguel

No, your question is not idiot, but perhaps lacks the words "fully reversible" There is no such thing; there is always losses, its one of the laws of physics, you just need to read more about the basics; and in the future when you re-visit this same post, will understand the responses. No, you cannot inject heat, carbon monoxide and smog into an automobile exhaust pipe to make the engine turn and expel clean air and fill the gasoline tank while getting a ride. Even with piezoelectric or motor/generator, cannot recover the same amount of electrical energy by reversing the action. Miguel

Hello. If I understand your question, you are trying to electrically heat something in the most efficient way. To heat water (or something else) as you say, there is NO more efficient way. Any electrical heater will work THE SAME. How many Watts you put in; and the temperature will rise the same amount with a modern ceramic heater, or a carbon resistor, a light bulb or a 1920 coffe brewer. The efficiency can be improved by confining the heat and eliminating heat losses with insulation, but a given power will always produce the same amount of heating. Go to a store and look for plain room heaters, you will see many models. If all are 1500Watts, all will yield the same heat, no matter if modern or antique or whatever the advertisement in the box says. Hope it helps, Miguel -I do not know what you mean by USB-

Hi. If you only have wire and a piece of iron; and cannot read schematics, forget about building an inverter. Go to a computer service center and politely ask for a discarded Uninterruptible Power Supply UPS. They are usually discarded when batteries fail, but all the guts still may work. The guts are exactly what you want: an inverter. Miguel

Hi. This is not my field of expertise at all, am begging your assistance. In a gasoline automobile engine, given the intake manifold absolute pressure, the displacement, the revolutions per unit of time, the air temperature and a throttle position reading ; is it possible to precisely calculate the air mass flow ? Or more information would be needed ? Miguel

The excavator won't be capable to push it in ? Then have the excavator removing soil from nearly under it until it falls into the hole. Gravity always works. Miguel

Hi. Hard drive motors do not have enough torque to use them as propulsion on a RC car. But they could be used for RC airplanes. The plan to use hard drive motors just because you have them at $0 is not a good decision as they add too much complexity to your project. Their control circuitry is meant to spin them at a steady speed to ensure data stream uniformity which does not go well with other applications. Miguel

Hi. Dig a huge hole in the ground next to the rock, and push it in. Then spread the soil all over the yard or where needed. Will take you 15 minutes of excavator rental. Miguel

Hi. Three terminal hard drive motors are three phase motors. You will not make them spin applying 12V DC to them. Follow the traces of those three terminals and do a web search for the integrated circuit that connects to. Look for its application notes and then you can saw-off the portion of the board containing the circuit and ancillary components to make it run. Miguel

NOPE !! The refrigeration compressors -or pumps if called that way- do NOT pump ANY liquids. They handle ONLY gas. The compressed gas becomes liquid AFTER it is cooled in the condenser stage downstrean the compressor outlet. After they absorb heat in the refrigerator evaporator, the refrigerant becomes gas again and that is what enters the compressor inlet. Compressors do not compress liquids. They are almost incompressible. Miguel

Hi. Yes, gases as refrigerant gases, air, etc. Seen it done to evacuate chambers; and can be improved as shown here: http://www.sas.org/E-Bulletin/2003-12-12/labNotesAS/body.html Miguel

Hi. Use the inlet side of a compressor rescued from a discarded refrigerator. It really sucks ! Miguel

Hi. Use paraffin as a filler in a box sorrounding the electronics instead. And consider a tethered robot if you want real time video. Miguel

.... And if you use the laptop on batteries, does the television gets interference ? If it does, you will be chasing your tail with the wall outlets; the interference is radiofrequency emitted by the laptop and picked by the television receiver with not much to do with the electrical wiring. Miguel

Hi. Yes, what you describe is commonly used to heat homes. But you do not need mirrors, you need the pipes painted black in a sealed box with a glass cover. If you circulate air trough the pipes, it will heat the home during the day. If you circulate water, it can be stored hot in tanks and its heat released also during nights. You can obtain about 1 KWatt/m². Make it 5m x 5m on top of your roof and your home will stay toasty all winter. Search for "solar heating" Miguel

¿ Why trying to find the complex way to do things ? You want a spark plug to spark, use a spark plug transformer from a car, motorcycle, lawnmower, whatever. Apply 12 VAC to it and watch where you stick your fingers. Miguel

Do not use polyestyrene foam as packaging. Use sponge instead. Only 50 metres? -piece of cake!- Helium balloons will do it, but there is risk the 50 metres can become 50 kilometres and get the first prize plus too many extra bonuses. A tiny leak with an aquarium hose valve on the helium balloon can be set for shorter distances and a very smooth landing and may need very little protection. If a strict path has to be followed by the rules ot the contest, a second air ballon can provide propulsion to the helium carrier while riding captive on a string from start to goal line. Miguel

------------> http://www.scirus.com/srsapp/

-----------> http://www.scirus.com/srsapp/

Very interesting, Samphire. If the tiny currents the neurons carry make equally tiny magnetic fields, varying magnetic fields should produce currents in them ! Then, the magnetic fields of soooo many electronics surrounding us should induce stray currents in our neurones, interfering with the nervous system, making us... crazy ? Miguel

JC1 : You will really, really bang yourself your head against a wall to bleeding when you grow up and read your post a few years from now. Miguel

Many pictures on the news show the discharge ends of the pump pipes at 10 -if not more- feet above the surface. The brutal flow reduction and increased amount of fuel makes no sense. And that pumping operation is conducted by "experts" ? The discharge ends should be as close as possible to water level to be efficient, probably doubling flow. SHAME ! -The land of waste- Miguel

Hi. The first; what size of a mylar mirror "umbrella" held by a reasonably far positionable satellite could produce a ~500 Km Ø shadow on earth? And the other; would such shade cool the sea surface a few degrees if projected several days on a path, enough to somewhat decrease the intensity of a hurricane ? Miguel

Hi. I left out a factor in the formula, am sorry. The correct one is here: http://www.imagineeringezine.com/e-zine/capacitance-3.html Miguel

70 feet² = 65032 cm²