Engineering

Any place where i can find information about helicopters with 2 propellors you know the two fan ones. I'm planning to make one (wired) with 2x 15000rpm 12v motor and some thermocol(styrofoam) and two plastic propellers. Any tips or suggestions. Also will the fan regulators(SCR) work in DC.

Anyone know anything about Dilution fans?

I found some free useful webcasts and resources (technical white papers) on this website and would like to share: TechOnline is an educational resources for electronics engineers mostly and alot more in the field of engineering and computer science. cchea

Can someone tell me the difference between using the units of pressure "bar" and "barg"?

If there was a giant magnet orbiting around earth is it possible to get into space simply by riding in a magnetic rocket? Or is there something that will make it impossible? Please reply.

ive been taking apart old harddrives and now have several of the motors used to spin the disks. id like to play around with them and im curious how to do it without burning them out. they all have three electrical contacts, so i need to know what each of the contacts are, so i know how to wire it, and what voltage i need to use. can anyone help me out?

Hi guys, I have been hearing a lot about Zinc-Air batteries lately. Do you guys have any ideas on how to build a powerful enough homemade one? Thanks ahead of time.

This is a project that is classified, but i need some help wiht it. yes, i know, some of the questions that will be asked here will sound very elementry to you, but i (even though i "only" have a 11th grade education and barely any handson experience in engineering) do have the skill to put things together without prior study. all i need to know are things like (Ex: "i know i need a battery to power a machine, i also know how to hook the battery up, but i just don't know what size battery i need to use) the basic components. can yo guys help me out? give me some links? somehting? this is all that i am allowed to post:

have we come up with any propulsion to use in space yet besides rockets or ion engines?if not y?

How about glass fiber for the construction of space habitats? Manufacture the fiber on the moon, wind it on spools, run it through a fabricator that can "weave" the fiber into structural parts and impregnate it with some kind of silicone or similar material to seal in air. Can we then manufacture a space habitat that can maintain its structural integrity for thousands of years? The trouble with any metal is that it will eventually corrode away, and silicon dioxide and silicate minerals are a lot more common and may be easier to use this way. A thick matrix of fiberglass would be very hard for anything to pierce. If the material is "woven" using fibers of lengths of h…

hey guys, this is my first post on the site. its probably a newbe question and im not sure if this is were it should be.... but here it is.... I am making some modifications to my computer case and i want in install some LED's. I know that when installing LED's you typically need to use a resistor to drop the voltage. I have two green LED's rated at 2.1V (2.8V Max) 30mA each. Could i simply solder them in series and connect them to my 5v form my PSU? I have been told this will work. I have also been told this will not work and to use resistors ranging from 1 ohm to 600ohm. im just looking for a little clarification, thx.

Dyson shells, ringworlds, orbitals, and the like - obviously these structures would all require materials of incredible tensile strength (less so with orbitals, perhaps), close to the strong nuclear force, etc., but could such a material ever be made? Nanotech seems to be coming up with materials with tensile strengths far above naturally occuring materials, so what are the chances something could be created with a strength close to that required by megastructures?

ok, according to some references i need 40,000 volts to make a spark plug jump the to electrodes!!!!!!!!! i have heard of some weird thing that converts 12 volts to 40,000 volts but i don't know how, where to find it. is their an alternate way to produce 40,000 volts??? i have heard that lasers need large voltages..... are their batteries that have high voltages.???????????????

There is no electrical section here on SFN so I figured I will just put it on the general talking forums. See, I have this problem. I have 3 utility outlets in my room. (120V of course) One outlet is occupied with my TV and my video/dvd player. The second one is occupied with my alarm clock. (That left a hole left). The third one is occupied with nothing. So whenever I have my laptop plugged in the second outlet with the alarm clock, my TV would get all wierd and fuzzy. Colour is not fusioning correctly and just messed up the screen. I became frustated, so I shutdown the laptop, and then the TV is fine. My question is do you guys have any idea what is happening here?

Hi, i was wondering, since our world is filled with satelite and radio waves, would it be possibe to take the electricity in those waves and use it as general electricty. AC or DC. I'm a complete noob to this and got this idea when i just got a satelite a few months ago. thnx

I was reading about RFID's and Richard Stallman's incident with the UN, and now I am curious as to whether or not aluminum foil can actually block radio frequencies. If it cannot, how about tin? If we wanted to be absolutely certain no one was reading an RFID tag, unless we wanted them to, we could make a lead-sheathed wallet of sorts, but this would be a little cumbersome.

I am planning on producing a glove that accomodates all the basic tech necessities on a micro scale. The glove will have provision for supplying light via solar power from the tips of the fingers. It will have a gps and micro camera integrated. AN mp3 system with speakers A mini storage compartment above the thumb for medicine like tablets etc. And a mobile phone. What i need is a place where i can get a gps chip ,touch screen chip,mobile phone chip thats small enough. Thanks a lot. Please give me some ideas on how i cam accomodate all these things.

Take an iron-nickel asteroid, core it, insert a chunk of ice into the core, seal the opening. Now, using solar mirrors, heat the asteroid, rotating it slowly so as to achieve some uniformity of heating. What's supposed to happen is that the ice within becomes liquid as the mirrors heat the rock, which migrates through the mass of the asteroid. The liquid becomes steam, steam pressure forces the now-molten body to adopt a spherical shape and the mirrors are removed. The thing cools, retaining its spherical shape. I read about this a long time ago in a science fiction book by Larry Niven and Jerry Pournelle. They didn't call it the Niven Bubble, that's my doi…

Hi, Does someone know why they don't start using white leds in those projectors? You need only about half the energy and what is much more important the lifespan is about 50000 hours. For most projector lamps that is more than a factor 10 longer. So what is stopping them to use LEDs? some info Lamps: Current home theater projectors are all working with a lamp example of a projector: http://www.projectorcentral.com/projectiondesign-F3_SXGA+.htm Here you get 4000Lumen for an 250W lamp (16 lm/watt), lifespan 8000hours LEDs: White LEDs have in best case 80lm/watt http://www.lrc.rpi.edu/resources/news/enews/Apr05/general251.html (available now bet…

Hi I'm not really sure if this applies to electrical engineering it may have more to do with quantum mechanics. I haven't be able for find any info on what happens when you pass an electical current through lodestone. Does lodestone conduct well enought to carry a current? Do the magnetic characteristics of the lodestone contribute to the strength or the structure of the electromagnetic field produced when electricity is passed through it? Thanks much.

1) Does the technology exist to use radar or something similar in space to detect other objects in space? 2) Is there anywhere in the world where you could launch a vehicle into space without it being detected? 3) Can all man-made vehicles in space be picked up on radar or something similar from the surface of the planet?

generally mass flow rate (mass dot) = density x volume flow rate but ive just read in a book that: massflow rate = volume flow rate x pressure ! ....this must be wrong it shows a "p" instead of the density symbol ...just wanted confirmation thanks

Hi, I know how to bias a BJT transistor to operate in the active region, so that the amplifier circuit can operate as a small-signal amplifier. Two methods (i) Use biasing resistors to form a self-biasing circuit. (ii) Use diode biasing, coupled with biasing resistors. Qn1 However, how do we bias the transistor circuit to act as small signal amplifier, if MOSFETs are used instead? Design of dc biasing circuit for MOSFET as an amplifier??? I read from my textbook that we need to bias the MOSFET in the saturation region, which is quite different from the BJT amplifier dc biasing design. The relation of MOSFET in saturation region is Id = K(Vgs - Vt)^2 …

A vapor-liquid separator drum is a vertical vessel into which a liquid and vapor mixture (or a flashing liquid) is fed and wherein the liquid is separated by gravity, falls to the bottom of the vessel, and is withdrawn. The vapor travels upward at a design velocity which minimizes the entrainment of any liquid droplets in the vapor as it exits the top of the vessel. The size a vapor-liquid separator drum (or knock-out pot, or flash drum, or compressor suction drum) should be dictated by the anticipated flow rate of vapor and liquid from the drum. The following sizing methodology is based on the assumption that those flow rates are known. Use a vertical pressure …

Here are the governing relationships for the makeup flow rate, the evaporation and windage losses, the draw-off rate, and the concentration cycles in an evaporative cooling tower system: M = Make-up water in gal/min C = Circulating water in gal/min D = Draw-off water in gal/min E = Evaporated water in gal/min W = Windage loss of water in gal/min X = Concentration in ppmw (of any completely soluble salts … usually chlorides) XM = Concentration of chlorides in make-up water (M), in ppmw XC = Concentration of chlorides in circulating water ©, in ppmw Cycles = Cycles of concentration = XC / XM ppmw = parts per million by weight A water balance around the…