My point is that "AC" in this context is the traditional socket power in which most people associate or relate to. The action of a DC circuit is alternating its current is not "AC" based on the common definition. Webster Main Entry: alternating current Function: noun Date: 1839 : an electric current that reverses its direction at regularly recurring intervals —abbreviation AC Due to the encoding associated with DCC the current cannot oscillate at regular intervals (Hertz). Inobu Once again the mentality! Wow!
Gosh, those darn $100.00 words. I'd like to know how you did that. This posting of yours has flat disappeared. You a magician? Never mind, I think you will find this encouraging. Inobu, You wrote: Will I ever learn. End quote. I wouldn't give it a second thought. You were doing your best to make this simple for a newbie. As it should be. So don't stop now. The electronics terminology is so far above most of our heads, that a discussion of it... isn't going to much matter. Particularly, to those of us who are less then knowledgeable about such things. That would be the likes of me. Summary, It don't matter...just chaff blowing in the wind. So, may I suggest we get back to simple. Keep it simple....(you can fill it in). There are newbies that want to get started and don't want to listen to....(again you can fill it in). Simple, I do simple. Just don't be calling me a simpleton. Well, hummm, that does have a ring to it. heeheehee Your ok Inobu, just don't give up.cool:
Aaah. I see where you're hung up. And as I pointed out in the bottom 3/4 of my post, you're right - from a certain point of view. Webster isn't wrong, but Webster isn't telling the whole story. Thing is, there's the "common" definition of AC, where it is constant frequency (and amplitude), symmetrical, usually sine wave voltage varying a set level above or below zero volts. For example, the 120V 60Hz AC we get through the wall. This might be termed the "layman's definition" of AC, since it is the type of signal most people are the most familiar with. DCC is most definitely NOT that type of AC. And nobody on this thread is saying that it is. However, there's the broader (and yet more strict) engineering definition of AC, in which the frequency and waveform can in fact vary in precisely the way the DCC signal varies. It *is* AC. It's just not the type of AC coming from the wall. It's more akin to an FM radio signal than wall power. The pulse width variations in the DCC signal do not change the signal in any way that would make it fundamentally "not AC". On the other hand, because of the usefulness of thinking of the signal (strictly speaking, incorrectly) as a "bipolar DC" signal, I actually like the way you described it in the OP. But strictly speaking it's still AC at the rails. I'll stake my MSEE degree on that.
So much chaff in the wind! laugh: And, it continues! They will get the message. We can hope. Let's see I'm taking wagers on who is going to win this debate...any takers?
Rick you have a point, and it is well taken. All this stuff about whether the DCC signal is AC or DC is dangerously close to arguing over angels dancing on a pin head. While it might be helpful for DCC newbies to understand how it works, they really don't have to, any more than they have to understand how the loco motor responds to the pulse control from a feature-rich DC controller. Using DCC can be brain-dead simple. Or it can be as complex as you WANT it to be. I thought inobu put together a really great beginner's intro to DCC. So good that I was going to (and very likely still will) ask his permission to repost it on my blog and elsewhere. Unfortunately, a potentially very useful thread got derailed over a dispute about how to classify the signal. And I, for one, fell hook line and sinker for it. I'm done. Have a good night, all!
Dad, I look at things from a definitive perspective. There is AC (Alternation Current). There is alternating current or current that alternates. The only way you can get AC (Alternating Current) from DC is with an inverter. The DCC booster does not have an inverter. Inobu Done
baffled:Well, I may have lost on that wager. Thanks guys for sharing and I will absorb what I can from your view points shared. I can only hope we can find a way to make this simple and take the complexities out of DCC. For those gifted in the knowledge of electronics...we look to you for help... we simplite types, just want to get up and running...and ultimately to understand and enjoy DCC. One thing I know for sure... you can't get AC out of purified DC. Does that help?cute:
Rick, sorry I see what happened - I missed your post while making mine. You are right. In our zeal totalk about things we find interesting us "sparkies" sometimes lose our audience. Inobu. We're wasting too much time (three pages already) arguing over the classification of a signal that the DCC user doesn't really have tocare about unless he's just curious. In the process, we're destroying the point of your useful OP, which was to give DCC newbs a quick, easily understood, high level explanation of DCC and how it works. For my part I'm sorry. I got into the debate too much and lost sight of what really matters. Let's just call the DCC signal "something else" and be done with it. We need to get on with keeping DCC easy. If we want to debate whether the track signal is a horse or a mule, we can do that privately or start another thread. OK now I really am going to bed. G'night all!
Twin Dad and Inobu, You guys are all good in my book. Each of you cares and that's what we need here on TB. I will check back in the morning. Good Night All!
Did the research and the post remains as is. The context in which NMRA uses the electrical current in DCC is to facilitate data transmission and the energizing of its electrical components. Inobu
Very true. The reason is that it is already AC, and the decoder converts it/rectifies it to DC by clipping the top, or the bottom, of the above or below ground projections so that directionality is imparted in the now-DC signal for the sake of the always DC motor.
You make a very profound point that allows me to see both aspects and reevaluate my position. Key point was "a rectifier will only process an AC signal" which is a true statement. Is the boosters designed to output an AC signal. No That is the difficulty that I have with this whole AC discussion, is the intent. The intent is to create a power source and transmission media. The circuit design is not of a AC inverter but and encoder. AC happens to be a by product. My logic has me to refute the AC notion. For example: If you sprayed your yard with a hose. I would not call it rain although it creates the same effect as rain. The intent is to water the lawn not create rain. This is the logic that I use and how I am able to convey information in a simple form. In any case you presented a very good point in a simple manner. I guess the rebuttal can and well be, " it is what it is". Inobu Getting late for me.
Arrrrgh! I was trying to say that all evening last night. Look, guys. We're in a thread trying to explain TT&TO operations simply and we've spent four pages debating whether the locomotive on the front of Eastbound #42 is a GP40; not a GP40-2. It doesn't matter. The only people who NEED to know what the track signal looks like are the designers of the boosters and decoders. Inobu you hit the nail on the head in your last post. The important part is that it is a special signal that carries both power and commands tithe decoder, and the power is always on.
I have been an Electrical Engineer for most of my adult life. I have antennas I designed on sattelites and on air craft of all sorts. In all that time, accuracy has always been important. Inobu's post was nearly perfect, except fot the DC comment, it was inaccurate from a technical perspective. The anology of the watering of the lawn versus rain is not quite correct either. It would be easy to tell if it was rain or a hose simply by looking higher than the yard at leaves on the tree or moisture on the roof or even at the neighbors yard. The change in slope that is part of the definition of Alternating Current in the case of the DCC carrier signal is where the edges roll down from the top or roll up from the bottom of the pulse train. It is the transition from flat to vertical and vertical to flat that is the change in slope that allows this to be called Alternating because anytime the slope makes an abrupt change like this, the current also makes a change. In addition, it is not proper to think of DCC in terms of DC or 60Hz AC because it is neither. It is in the digital domain and such notions are replaced by terms like Pulse Repetition Frequency and the unit of Pulse Width. There is still a center carrier frequency that is more commonly called the system clock frequency and it is used to set the the package frame space for the digital information. The DCC command is just the modulation of the of the clock frequncy to hold data, in much the same way FM (Frequency Modulation) radio worked before the HD signal. Further to the point, if a signal was applied to the current in the wall, depending on what the signal was and the type of modulation, it may look nothing like the sine wave you are thinking about. But is still AC because that is what it was before the infomation was applied through modulation. Modulation is the key here. If there were no data pulses comming out of the DCC controller, you would see a pure square wave. But commands are modulations applied to the pulses to make them different from the carrier signal so that when that signal is received, the carrier signal is removed and the differences from the carrier is the information that was transmitted. The digital realm is similar but different and direct comparisons to AC or DC are just not valid.
David (and everybody else!!!), You're absolutely right. But IMHO (and I think this was BarstowRick's point), this is the wrong thread to be making such distinctions. I think the OP's intent was to write what you and I might consider a "User's Guide"... and the user really doesn't need to know or care what sort of signal the DCC track signal is any more than they need to understand the differential signaling in an ethernet cable in order to use this website. It's all very interesting stuff, but often just serves to confuse more than educate. We can start a "DCC Overcomplicated Beyond Belief" thread and go into the hairy details of the interface to no end. You and I and a few others could have a great time with that. In this thread, I think we'd be much better off to simply label the DCC track signal as "something else different from wall mains AC and from traditional DC" and let it drop. By debating the classification of the track signal, we're only confusing people (including each other) and furthering the myth that DCC is too complex for the beginning MRR user. Ironically, in a thread that's supposed to show how simple it is.
While I agree with the comments that a beginner doesn't need to fully understand the DCC waveform, I also feel that it is important to not give out incorrect information when trying to simplify things. To state that DCC is not AC is incorrect. As I have repeatedly said, and never implied otherwise, it is not the same as what comes out of the wall socket, but it is still AC. When trying to simplfy DCC, I think it is perfectly OK to just say that it is different than the AC that comes from a wall socket without going into the details of how it is different, but I don't think it is OK to simply state that it is not AC when it is.
I absolutely agree, and that is precisely why we should never have gone down this rabbit hole in the first place. Four pages in, and rather than simplifying DCC for the user, all we've done is debate and confuse the issue. The original purpose of the thread has been lost to a debate that could have been irrelevant to nearly everyone, had one detail of the OP been worded a little more accurately, and had the rest of us (myself included) not dogpiled on that one detail. We're all sitting around arguing "The sky is blue! No! It's blue! No it's not. It's clearly blue!" The important point Inobu was trying to convey is that the DCC signal is not the same as the AC mains signal. That's not even a point for debate. Everybody here agrees on that point. We're all arguing about the technical definition of AC vs. DC with respect to the DCC signal, which is effectively and functionally irrelevant to anybody who isn't actually trying to design their own booster or decoder. Unfortunately, the way he chose to make that point (though it can be an interesting way of visualizing the signal) was to describe the signal incorrectly. And that got all us "sparkies" off on a tangent. So here. Let's all just agree on these four points, bury the issue, and get on with the original point of the thread, which was to simplify, not to obfuscate, DCC. The DCC signal is NOT the same as the AC power coming from your wall plug. It doesn't have anything to do with that, really. The DCC signal is NOT the same as the DC signal used traditionally to control trains. Doesn't really have anything to do with that, either. Except for the "controlling trains" part. The DCC signal IS a clever combination of a constant power supply to the locomotive and a digital messaging from the command station to the decoder. The DCC signal, strictly speaking, by the engineering definition of the term, IS an AC waveform. Nobody but the decoder and booster designers should really care, though, as long as points #1, #2 and #3 are understood. Sorry. I'm a little frustrated. I see in this thread a type of basic communications foul-up that plagues my work days all too frequently, and it just aggravates the devil out of me. And I'm more than a little mad at myself for diving in and trying to "win the debate" rather than trying a different tack and getting the thread back on track a couple pages ago.
My intent is to convey the most accurate information I can, My reasoning and logic is different than most and key principles in my problem solving ability. Based on that premise this debate ensued. So, take this thread as an example of intent and focus on the intent and gather information that is important to you. I think the mindsets are different and impede the growth of the hobby but that is the way of some worlds. Make this thread work for you not the other way around. Inobu
Well, guys...I don't know what to say. You needed to hash this out and that is fine but it's not in keeping with original post. As in "Simple". I still don't know who the winner of this debate is and a bunch of us are about to give up on our bets. Grin! It's all good. And I followed it quite well...better then I thought. So, I went out and rained on my lawn. It turned yellow though and smells funny. I made sure the tree leaves were wet so everyone would know it was rain. That was a trick to accomplish...as old as I'm getting. Easier when I was younger. I then went down to the desert to take in a hosing flash flood. Darn near got washed off the road. I did go out and run my DCC equipped locomotive. The MRC programs, programmer equipment keeps asking for CV values and I still stare off into the darkness. You can hear me asking what, what, what does it all mean. Mumbling the same thing over and over as I walk around taking care of the chores. I keep reading the CV instructions and none of it makes sense. Flow charts are available but with little to no explanation. Confusing as...well! Thanks for sharing your points of view and I'm glad to know there is a built in rectifier that turns AC into DC for the DC electric motor. Sort, of had that one already figured out....though. Oh, heck I just got to rattle your cage...ahhh...thread. Just a little. You need a good heckler to get you back on track. These derailments and dead end spurs...ahh... discussions are driving me nuts. Shucks, I'm mad as hell at DCC and the lack of directions that make sense. There are reams and reams of written material that speak to the issue but when it comes to the CV's....nothing....easy to understand. I seldom have difficulty reading through directions and tend to catch on quickly. Just not this time...around. Heck, if this had come around when I was in my 20's or 30's. I'm sick and tired of rereading how it got started, how to wire it, what size of wire to use (that's actually to large and overkill) and what the AC does to the DC. I want to run the #@^^ thing. I've downloaded two computer soft ware programs but I have to purchase a modem at $75.00 to $100.00 each and more if I pay CA's sales tax, just so I can use it. Everytime I turn around it's another $35.00 to $56.00 to $134.00 and everywhere between to buy decoders or sound cards. Dime and nickel...heck...these are more like quarter and fifty cent pieces. The sound lacks the deep base needed to simulate a hard pulling stove or diseasel. Tinny, lacking depth and quality of the original sounds... is the best description I can use with regards to the sound. To toy like for me. Oh, I better relax... before the pop off valve goes off and I have to pull into a siding to cool down. All things aside, I wish you had heard me when I said all this electronics stuff is "Chaff in the wind," to those of us who know very little about electronics. What we need to know is pretty much covered...all ready! The most difficult part about this is a need to know, how to set-up the CV's. What values should we start at? A brief explanation as to what they do...cause and effect. Well, I've rattled on long enough. Clearly DCC is not simple. See previous postings and discussion on something to do with AC, DC, and DCC. That should prove my point. Simple? Not to this guy! Not to this dumb donkey...I can't say dumb ass because that may not be appropriate. baffled:
