Cordless Mouse & Windows Vista

[Amianthus]

It also provided AC power that was converted to DC,

Pretty good description. Only quibble is that the power produced was not AC, but pulsating DC. Both can be used to energize transformers.

[hnumpah]

Look at the signal on an o'scope from a generator - it's a sine wave. AC.

A solid state DC/AC converter gives the 'square wave' I think you are referring to as 'pulsating DC', and yes, it can be used pretty much like regular 'sine wave' AC.

[Amianthus]

Look at the signal on an o'scope from a generator - it's a sine wave. AC.

A generator produces DC. An alternator produces AC.

[hnumpah]

You might want to grab a basic electrical theory book and check that. A generator, driven smoothly at a constant speed, produces a smooth sine wave - pure AC. That's what you've got coming into your house, once it's been stepped up and down a few times. Simply put, the voltage rises smoothly as the motor (belt, whatever) turns the windings on the shaft of the generator past the stationary coils until they reach the point where the voltage peaks, then begins to drop smoothly as the windings continue turning. The voltage will go 'negative' just as smoothly, until it reaches the maximum 'negative' peak, then begin to rise again. You get a smooth AC sine wave, something like this ~ (tilde, in case the forum won't print it right).

A DC/AC converter, whether solid state or vacuum tube, takes the DC voltage and chops it up into a square wave - hard to do that on a keyboard. Since it switches almost instantly, the leading and trailing edges of the wave are almost completely squared off. As you step it up or down to get the voltage you want, it will appear slightly less 'square', but will never be a perfect sine wave without more circuitry to refine it and shape it.

[hnumpah]

Don't know why I didn't think of this earlier...

Sine wave


Square wave

[Amianthus]

You might want to grab a basic electrical theory book and check that. A generator, driven smoothly at a constant speed, produces a smooth sine wave - pure AC.

Early motor vehicles tended to use DC generators with electromechanical regulators. These were not particularly reliable or efficient and have now been replaced by alternators with built-in rectifier circuits.

http://en.wikipedia.org/wiki/Electrical_generator

An alternator is an electromechanical device that converts mechanical energy to alternating current electrical energy. Most alternators use a rotating magnetic field but linear alternators are occasionally used. In principle, any AC electrical generator can be called an alternator, but usually the word refers to small rotating machines driven by automotive and other internal combustion engines.

http://en.wikipedia.org/wiki/Alternator

[Plane]

http://www.howstuffworks.com/


A lightbulb of the type that Edison invented has a small coil of tungsten wire enclosed in an airless glass bulb, when current passes through it, it's resistance causes heat ,and when hot enough, light, this is called an incandescent light .

http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf
A florescent light has a tubecoated with phosphorescent material and encloses a pure gas at a very low pressure and has a little coil of wire at each end , last but not least it has a tiny bit of mercury. A high voltage spark from the "ballast" is necessary to kick the bulb over from its cold unconductive state to a conductive plasma, once this is done a very small amperage at a rather lower voltage is sufficient to keep the gas an mercury vapor in the plasma state. The Plasma gives off ultraviolet very efficiently andvisible light inefficiently but the phosphor coating adzorbs ultraviolet and re-emits visible light .


http://en.wikipedia.org/wiki/Light-emitting_diode
An LED is a diode a simple P/N junction with the addition of doping with material that likes to shed photons when electrons are passing through.
http://computer.howstuffworks.com/diode1.htm
At a P/N junction the P materiel cannot give up electrons without huge voltage but the N type materiel can give up electons aplenty with a mere .7 volt jolt so electrons going from the P type materiel to the N type are going uphill and seem to be blocked  , but electrons traveling to the P type from the N type are going downhill and meet little resistance.

Diodes can be arranged in sets that convert AC current to DC and this device is known as a rectifier.
A more complicated device that produce AC from DC is a inverter and are handy to have installed in your work truck.

A generator is generally wired to produce DC and an alternator is wired to produce AC but because an alternator can be made lighter in weight and can produce useable current at lower RPM it is often worthwile to use an alternator and rectifier set as a DC generator.

[Plane]

There are several ways to wind a generator , but the key difference between a generator made to produce DC and one made for AC is whether it uses slip rings or a commutator.

An alternator is a certain class of generator,this type cannot be wound to produce DC .

The simple generator model is a coil of wire spun in a magnetic field. In the winding of the generator an AC sine wave is produced and if the takeoff is slip rings so is the output. If the takeoff is a comutator or split ring an otherwise identical machine will produce pulsed DC. Split rings convert the sine wave into a current that falls to zero and rises to maximum in sine shaped hills that are always the same polarity. A generator that uses a commutator generallycan be used as a motor when power is applied to it.

[hnumpah]

You got a motor, or other drive source. It turns a shaft. The shaft turns a pulley attached to a belt that turns a shaft that is connected to a generator or the shaft from the motor turns the generator directly. The generator produces an AC sine wave.

When I bought one for hurricane season 'way back when, they called it a generator, not an alternator. We had a surplus 400-cycle one to run our emergency lightstands (and coffeepot) when I worked with a volunteer fire department. They called that a generator as well. Power plants use 'em, hooked up to steam turbines or whatever, to produce the power you use in your home. Last I looked, those were generators as well. I really don't care what you call them, but that is what I am talking about. If you want to play word games and 'I got to be right', go ahead. I'm not an auto mechanic, but with over 25 years experience working in the field as an electronics engineer, I'm comfortable I know what I'm talking about.

[Plane]

You got a motor, or other drive source. It turns a shaft. The shaft turns a pulley attached to a belt that turns a shaft that is connected to a generator or the shaft from the motor turns the generator directly. The generator produces an AC sine wave.

When I bought one for hurricane season 'way back when, they called it a generator, not an alternator. We had a surplus 400-cycle one to run our emergency lightstands (and coffeepot) when I worked with a volunteer fire department. They called that a generator as well. Power plants use 'em, hooked up to steam turbines or whatever, to produce the power you use in your home. Last I looked, those were generators as well. I really don't care what you call them, but that is what I am talking about. If you want to play word games and 'I got to be right', go ahead. I'm not an auto mechanic, but with over 25 years experience working in the field as an electronics engineer, I'm comfortable I know what I'm talking about.

It isn't wrong to call any of them "generator" but " alternator " is a specific type.

400 Hertz is common on Aircraft because the generator and motors and wiring can all be lighter for the same power.

[Amianthus]

When I bought one for hurricane season 'way back when, they called it a generator, not an alternator. We had a surplus 400-cycle one to run our emergency lightstands (and coffeepot) when I worked with a volunteer fire department. They called that a generator as well. Power plants use 'em, hooked up to steam turbines or whatever, to produce the power you use in your home. Last I looked, those were generators as well. I really don't care what you call them, but that is what I am talking about. If you want to play word games and 'I got to be right', go ahead. I'm not an auto mechanic, but with over 25 years experience working in the field as an electronics engineer, I'm comfortable I know what I'm talking about.

You were talking about cars, and specifically referenced cars from the 50s. In that situation, when you say "generator" it means DC, and "alternator" means AC. And you were even referencing old cars (pre 1960) which all pretty much had only DC generators. The 60s were a transition period, where some cars had DC generators and others had AC alternators. Pretty much all cars from the 70s on use alternators, because they're lighter and cheaper.

In general, nowadays MOST "generators" produce AC because nearly everything runs on AC. As Plane said, an alternator is a specific type of generator that ONLY produces AC. And since alternators are lighter and cheaper, even "DC generators" are typically alternators with rectifiers and filters for output conditioning.

However, my initial quibble was in regards to older cars with DC generators. In that case, the output is pulsed DC, and not AC. And that was the only thing I said.

[Xavier_Onassis]

Are all alternators AC?  My car runs on DC, I am pretty sure. At least the starter and other devices. It's a Diesel, so it doesn't require any electricity at all for the coil, condenser or spark plugs, because it has none.

Once started with the glow plugs, it will run until the fuel is gone even if the battery is dead.

I was of the opinion that since the starete and other devices in a car were DC, the alternator was DC.

[Amianthus]

I was of the opinion that since the starete and other devices in a car were DC, the alternator was DC.

An "alternator" is always AC. You can convert the output to DC, as both Plane and I have said.

That's where it gets it's name - it produces "alternating current (AC)" so it's an "alternator".

[Xavier_Onassis]

I saw your flashlight demo, and was amazed, because no flashlight I have owned would do this.

None of those I have in the house will, either.

[Plane]

I saw your flashlight demo, and was amazed, because no flashlight I have owned would do this.

None of those I have in the house will, either.

Possibly ,in your particular flashlights the baterys fit poorly backwars and leave a gap where they need contact.

Or some of them may be LED which does require correct polarity.