DC and AC differences?
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Bronze Member Username: PanamanianPanama cityPanama Post Number: 66 Registered: Aug-05 | Why if the alternator generates AC it must be change to DC? or viceversa? Will that make equipments to fail? or just won't work at all? |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9399 Registered: Dec-03 | why don't you go to college and take some cources on basic electricity? that may help you out a lot (and save me a lot of time hahaha) Originally, cars used 6 volt DC generators for electrical needs like powering the magnetos to fire the spark plugs. As more electrical devices were added to cars, like headlights, horns, wipers, and so forth, more current was needed. At this point (late 50s if I recall?) the switch was made to a 12 volt DC system and the use of alternators instead of generators to supply the needed current. Everything was still DC based though, so the AC current produced by the alternators is rectified to DC then regulated to 12 volts for the car's equipment. Just think, there's a push now to move away from 12 volt electrical systems in cars and go to a new 70 volt system. Now that'd be a dream for car audio people.. if you don't mind buying all new amplifiers and head units. |
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Bronze Member Username: PanamanianPanama cityPanama Post Number: 67 Registered: Aug-05 | but why does it has to be ""rectified""??? (to DC) again? |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9443 Registered: Dec-03 | if you don't understand the difference between AC and DC voltage, you really have no business at all doing anything with electricity, including car audio. pay someone to do this for you until you have taken the time to study up on basic electrical principles. try www.bcae1.com for starters. I'm not holding your hand through all of this.. you have absolutely no idea about anything to do with lectricity apparently and nobody here has the time to teach you what it takes a lot of time and effort to learn on your own no matter how much time someone else spends trying to explain it all. it's even worse when I have to translate poor English skills along with everything else.. no offense. |
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Gold Member Username: FishyTamarac Ft.Laud, FL USA Post Number: 1485 Registered: Sep-04 | The reason a car's electrical system is DC(I think this is your real question) is because there's no such thing as an AC battery. -Fishy |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9454 Registered: Dec-03 | magnetos (pre-distributor_ used DC voltage, as do distributors to fire spark plugs (the only reason cars really need electricity to run when you get down to it) but I think he's asking why cars have to be DC, and what happens if you feed acar AC electricity. If you want to see what happens when you feed a car AC voltage though, just swap your battery cables some morning, and put the positive cable on the negative terminal and vice versa. same effect as running AC voltage. you'll see a lot of sparks, some fire, and a lot of magic blue smoke escaping from anything electronic. |
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Bronze Member Username: PanamanianPanama cityPanama Post Number: 69 Registered: Aug-05 | you used to like me GlassWolf, not anymore. you're not easy going at all. |
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Bronze Member Username: PanamanianPanama cityPanama Post Number: 70 Registered: Aug-05 | you used to like me GlassWolf, not anymore. you're not easy going at all... |
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Gold Member Username: CarguyPost Number: 3965 Registered: Nov-04 | Panamanian, you have to understand. GW gets tons of questions all the time and it is not easy. Especially if the person has no background in electronics. I am sure you've faced similar situations like that too. Anyhow, Fishy still luvs you so don't fret.  |
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Bronze Member Username: PanamanianPanama cityPanama Post Number: 71 Registered: Aug-05 | It's not about that, it's about being humble, if you know everything, it's ok, but try not to show off that. Also, this forum is to help each other, not so? if someone is bored of my question, just dont reply them, and that's it, instead of critics. Comprende? |
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Gold Member Username: CarguyPost Number: 3966 Registered: Nov-04 | Well GlassWolf did give you some very good answers with some suggestions. Don't take it as an insult. He was just getting frustrated cause lot of people aruge instead of listening. Look at his post number, it's almost 10,000. That is a lot of free help. I can see how you could take his "advice/suggestion" the wrong way, but I am sure he didn't mean it that way. Who knows, you might even enjoy taking the course. It's not like taking a cooking class. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9461 Registered: Dec-03 | trust me on this. if I didn't like you, there'd be no mistaking it. there's a big difference between mild annoyance or frustration with a single thread, and outright hating you. anyway the root of this problem is you're putting the cart before the horse. you want to know answers to advanced electrical issues without the most rudimentary understanding of electrical prinicples.. This is like taking 3rd year industrial control circuit classes in college before you get done with first semester orientation courses. see the problem? you don't have the basic knowledge yet to build on, and I don't have the ability to teach you that much over a public internet forum. I spent years in college, and even more years in the field learning what you want answered in 500 words or less, through a translation barrier. I'm sure based on that you can understand where my frustration stems from.. especially when I seem to devote a lot of time answering and re-answering the same threads from you without any feeling of getting anywhere doing it. |
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Anonymous | "anyway the root of this problem is you're putting the cart before the horse. you want to know answers to advanced electrical issues without the most rudimentary understanding of electrical prinicples" i believe thats how ppl get curious and begin to learn i know lots of times i embarrass myself asking questions to things i have no idea about and then ppl give that frustrated laugh because my uneducated questions are so far fetched and so instead of continuing to learn many ppl stop asking and are less educated from ridicule i would have much rather seen glasswolf break it all down for you instead of watching him answer the same question over and over again every other day he answers them and i get tired of coming here and reading them but i can understand how good an answer is when its custom to your situation just like an enclosure custom built for your subwoofer and i also know what its like when someone doesnt understand a word.. instead of teaching them the alphabet all over again, well you get the idea |
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Gold Member Username: CarguyPost Number: 3971 Registered: Nov-04 | Just remember, he's providing FREE service. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9479 Registered: Dec-03 | you may be curious about calculus, too.. but would you want to take a class in it without ever having learned even algebra or trig? he wants to know not just the basic difference between AC and DC electron flow, but he wants someone to explain what happens to electrical devices and how they react to each. You can devote semesters to that in college just learning about PNP junctions and so forth, which is what he needs to do to understand why you can't send alternating current to a circuit designed to operate using DC voltage. Even your home electronics use DC voltage once you get past the power supply, but most people probably don't realize that since they plug their stereo systems into an AC outlet in the wall. |
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Gold Member Username: FishyTamarac Ft.Laud, FL USA Post Number: 1498 Registered: Sep-04 | I don't mind answering or trying to answer the "stupid" questions. A lot of times those are the ones many of us are afraid to ask, but Glass is right. To understand some of the more complicated things you need to get a handle on some of the basics first. Thats why they have prerequisites in College and the reason that if I ever plan on getting back in school to finish my OE degree I'm just about going to have to start all over again(its been a while). About all I remember about PNP/NPN junctions is that they are part what makes up a transistor, germanium is in one of them somewhere, the base and emitters are backwards from each other(or something), and that transistors are electronic switches which require a certain DC voltage bias to operate. I also remember that fourier transforms were a big PITA. :P As far as AC versus DC goes its not all that complicated. DC simply means that the current or voltage remains constant. AC current or voltage simply "alternates" back and forth between a greater and lesser(usually negative) value. Other than simple resistors(heating elements, light bulbs, etc.) components designed for DC applications don't work, or at least don't work like they should, in AC applications and visa versa. For example a DC electric motor will oscillate back and forth when AC is applied and an AC motor will just turn less than half a revolution(unless its 3 phase, like 220v stuff) and stop when fed DC. Then there's solid state(the PNP deal Glass was referring to). Although certain solid state circuits can be used to amplify an AC signal(read music and your amps) they require a DC power supply to operate, be it 5v, +/-5v, 12v, +/-12v, +/-70v, etc. To fully understand or explain exactly why I'd have to brush up on the linear device stuff myself. Its best just to remember that in certain situations its advantageous to utilize AC(voltage stepping with transformers for example) and sometimes it better to use DC(like storing energy in a battery, coil, or capacitor). Usually the two don't mix so don't do it. That enough luv for ya Pan? -Fishy |
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Gold Member Username: CarguyPost Number: 3992 Registered: Nov-04 | Fishy get back to your OE degree program, the grass is not greener on the other side except the ones I painted. |
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