“Ordinary DC works (in great oversimplification) by shoving electrons in one direction, and”
Ahem, yes, like those electrons that orbit the nucleus in Bohr’s “model” of the atom. And wander through the airwaves or the “ether” remember that stuff?
You know current isn’t electrons actually flowing or transistors couldn’t work. And so on.
As I said and you confirm, there is no such thing as a square wave but it can come in handy to be able to describe a unicorn so we invent terms that may not accurately describe anything real. Point being the “instantaneous decay” problem which is just another way of saying that a displayed square wave isn’t square. You can draw one fairly accurately but you can’t make one.
Your post was informative as you no doubt intended, thanks. I came to the same conclusions after further pondering. All this discourse has been very helpful to me in my inquiry into DCC.
Yes, essentially point carriers of very well-defined charge, with very well defined virtual mass. I’m sure you’ll whine they are ‘theoretical constructs’ but they have been just as good as other subatomic particles as engineering working assumptions for many years, first in electricity and then in electric power. I think it is safe to continue working with the assumption that “they” behave as described as there is so much interesting nuclear physics associated with them and their ‘heavier’ versions.
Incidentally the stuff that ‘wanders through the airwaves’ isn’t electrons. You really should look stuff like that up before shaming yourself further in postings.
And you think current is… what, exactly? ExB? Magic displacement? “Waves” in the “luminiferous aether”? Hint: what is a coulomb, and why is it important to amperage?..
Again there is so much physics on conduction that relates to electronics that it is comical to hear a discourse ‘debunking’ it as if you knew something secret the rest of us don’t. You probably think nerve conduction is electronic, too. What’s next, that holes in semiconductors don’t exist either, because you can’t have charge less than zero?
And it’s certainly on and on: this is something like the sixth field I’ve seen you discourse on that you haven’t really understood, but that doesn’t stop you from browbeating those on here who I think actually might.
Here is something that every 19 year old law student (hmm) would be familiar with - - that old evidentiary adage, He knew that he did not know whether or not he knew.
I think the issue here is different. He is quite sure he knows whether or not he knows. It’s whether he does know that is at issue.
Now to cut him some slack, there is that aspect of ‘knowledge’ my father would expound after the 5th bottle of Old Dutch Philosopher – the part you can’t know. No one has ever ‘seen’ an electron and it does not behave like a true particle (other than statistically). Likewise no one can make a ‘perfect’ square waveform in a number of respects. And you can certainly have ‘currents’ with, for example, protons in fluids, or holes in some semiconductors. Perhaps my favorite is phlogiston, the career-wrecking politicized ego-ridden global-warming-style consternation of the 18th Century.
The problem is that if you’re going to disparage that sort of thing in practical use, you have to know the degree to which the theory applies or is a ‘good predictor’ – certainly for technology, and in some cases for science. As Copernicus pointed out (long before Fourier) there’s no reason why epicycles sufficiently superposed won’t generate any orbit … just that treating the Earth’s motion as if the orbit were heliocentric gives you easier calculations for accurate feast days.
Yes, many of us EEs also had to take enough physics so we know the conventional way circuits are discussed is sort of backwards from how it really works in the physics world. But it works fine as a model to describe the behavior of all common electronic components.
That’s a pretty lame excuse, that WiFiTraxx isn;t making a decoder. No, they aren;t. But they ARE making a device to be used IN PLACE OF a DCC decoder and even outfit it with the standard connection plug that is provided in many locos so you don;t have to solder wires in - AND THEN WIRE IT BACKWARDS. The AirWire board is NOT a DCC decoder, either. It doesn;t respond to DCC signals on the track, it responds only to radio signals sent from the AirWire throttle. It connects between the power source and the motor, in place of a decoder. They just happened to not do their lighting circuits backwards, so if you are adding AirWire to a loco that already had an NMRA 8 pin DCC decoder socket, you can just plug it in, no changes, and everything works, unlike the WiFiTraxx board.
AirWire at least also has features people have come to expect in a controller - a knob, which you can click to change direction, so no hunting for a button, toggle, or a part of the screen to tap on, and a screen to display info or walk you through configuration settings. Best of all, the same throttle works with their DCC system. so you could use their DCC system on your basement HO layout, then take the throttle outside and use it to run your dead rail, battery pack on boards, G scale garden layout. Same throttle, no need to learn two different control systems.
It is not the ‘personality defects’ at issue – we all have them, me more than most. It’s the making of claims of superior expertise or experience that contain things that ain’t so. Those need to be corrected before the susceptible jury of modelers reading for technical advice are led into rendering an unjustified verdict…
We all love the sinners, but that won’t stop us from hating sin…
I make no such claim. The only area where I would think to do so, and I do believe me, is in my profession and strangely we are forbidden from doing so. That’s strange because of the powerful egos bouncing around in my profession. Only brain surgeons and architects outdo us in that respect.
My style may give the appearance of smug superiority but that is in the eye or the receiver, not real at all.
I have two more questions arising from this thread:
What number of trains can one operator reasonably expect to control on a home sized layout? We have three DC controllers and running three trains simultaneously seems very challenging for one operator. We have two continuous loops and one yard so in theory operating three trains should be simple.
I deduce that one DCC throttle can control only up to 6 trains simutaneously operating and wonder if the up to 5 that are cut loose from the human operator at any one time are controlled by some sort of looping within the decoder or by simultaneous transmission of up to 6 streams of packets by the DCC control computer. I infer the latter as it is hard for me to see how a decoder could preserve the signal internally. That would also explain why power interruptions cause signal dropouts even with locomotive keep alive circuitry. The DC power can be stored onboard but not the DCC signal stream.
My current understanding explains why the MRC Tech 6 should have a significant market having the part of DCC that allows stacking of 6 locomotives into one throttle (assuming there would be only the one operator) and also providing for simple conversion to DC only running at the push of a button.
not looping within the decoder; the decoder is in the loco.
a single DCC command station communciates with all cabs (user interface) and generates the DCC signal to one or more boosters that provide power to the track. the command station will sequentially generate a DCC frame for each active loco. less than 8 msec/packet considering that the max bit is 200 usec and there are ~40 bits in a typcal frame (see S9.2 or all standards, S9)
i’m not sure what the max # of locos is for any one system but 100 would be conceivable. i think NCE will poll up to 64 cabs.
errant information is confusing to other readers. i think it better to state things as your understanding (e.g. “deduce”) rather than facts
I am confused about the subject of this thread. I’m DC so most of this thread is over my 79 year old brain but I keep trying to learn. I started out reading rrinker’s starting post about LocoFi.
rrinker on 7/27/20 wrote:
“. . . review the LocoFi system. . . . . . But they blew it - on their decoder, the function wires are positive and the common is negative - exactly opposite the DCC standard!”
So, I went to the LocoFi web site and found in thier FAQ that the wiring was in fact not DCC compatible for 8 pin. You do need to change the wiring in DCC ready locos to get LEDs to work. Thus, rrinker is correct.
I thought this thread was all about LocoFi but then on page 5 rrinker brought up WifiTrax and said it was backwards.
rrinker on 8/11/20 Wrote:
“That’s a pretty lame excuse, that WiFiTraxx isn’t making a decoder. No, they aren’t. But they ARE making a device to be used IN PLACE OF a DCC decoder and even outfit it with the standard connection plug that is provided in many locos so you don;t have to solder wires in - AND THEN WIRE IT BACKWARDS.”
So, I went to the WifiTrax web site but I cannot find that a “used in place of a DCC decoder” product by WifiTrax. They do make an 8 pin NMRA DCC standard compatible wireless interface to a DCC decoder that does process the incoming two track wires. I found this document for the inerface product “WDMI-35 Wi-Fi/DCC Loco Interface Module Getting Started” but it shows to be compatible to the 8 pin NMRA. There is nothing that indicated that the common was backwards.
What am I missing? Yes, most of the commentary in this thread I do not understand but I am missing something in going to the LocoFi and WifiTrax web sites.
This will be an interesting question to ask the various modelers here. I have generally thought that most of the ‘multiple train’ control involved the ‘club night lite’ operating sessions, where people get together to run on a private layout. If I were going to run multiple trains at once it would be mostly to ‘watch’ (meaning only intermediate use of any controls, with some form of automatic otherwise) or to run just one at a time. For DC this would immediately imply complex power management and ATS-enabled signaling; the operation would also benefit from ‘interlocked’ route selection.
I would agree, and it would be comparatively simple to assign a ‘cab’ to each and have the trains merrily go when no one is tinkering with the corresponding settings. We had a recent thread on who did and didn’t like to do that sort of thing.
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I deduce that one DCC throttle can control only up to 6 trains simutaneously operating and wonder if the up to 5 that are cut loose from the human operator at any one time are controlled by some sort of looping within the decoder or by simultaneous transmission of up to 6 streams of packets by the DCC control computer.
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This is a place you could reference ‘primitive’ technology. There is a limit to the addressable bandwidth in DCC, but to my knowledge little control storage apart from CVs. Adding the necessary information plus overhead plus any guard band between addressed instructions will give you the required bitrate… which must fit within the modulation rate of the signal.
The only one that truly allows you to have live control of more than one train at a time is Digitrax, their full featured throttles have 2 knobs, so you cna have 2 trains actually under control (meaning not having to push any buttons or anything to switch between them). You can have many running at the same time, just good luck trying to switch back and forth between them. So I’m going to go with 2 as a practical maximum, because I can actually have them under control, just turn the respective speed knob, with my Digitrax throttle.
The limit of 6 is very much system dependent. Right now I still have my original Digitrax Zephyr as a command station, it can handle up to 12 locos. The larger command stations can handle 100 or in the case of the DCS240, 400. Theroetically, you can start up all those locos from one throttle, the Digitrax system design does not limit the number of locos ‘controlled’ by a throttle to some limit based on the throttle’s memory. In any case, only the loco who’s address is shown on the display is actually under control of the throttle’s knob and buttons.
This is where you seem to misunderstnad something about DCC. The command station generates the DCC data. It is continually sending packets for every loco that is running. The throttle doesn’t do that, althought he throttle does update the command station based on user inputs. Either by sending the updates in a peer to peer system like Digitrax, or by being polled like NCE. The decoder doesn’t need to remember anything, it gets a steady stream of packets. There is usually a timeout setting in the decoder that tops it if it doesn’t see packets for some period of time, likewise the command station may see a lack of updated information from the throttle as the loco no longer being controlled, and may also stop the loco. Packet timeout on the loco side is part of the NMRA standards, the throttle bus and command station communications are left up to the individual manufactur
Further on the DCC sisgnal - since the same packets are repeatedly sent by the command station, it’s not actually an issue if a loco misses a packet or two addressed to it. Another will be along. That’s why there is no need for a acknowledgement for packet reception.
The total available bandwidth allows for hundreds of locos to run at the same time. Most clubs don’t come anywhere near this, but there is one well known layout, the owner has switched DCC systems more than once to get to the point where the wired and wireless throttles can reliably support the number of simultaneously running locos during his op sessions. If anyone stresses DCC’s capabilities, it’s him. Note the issues experienced over the years are entirely on the throttle/command station interface, NOT the DCC protocol. Even with so many trains moving at once (and this layout is big enough to handle them all, it’s not a whole bunch of trains all chasing their tails), you press the horn button and the horn sounds. You slow down for a station stop, and the loco you are running slows down.
Not bad for a ‘primitive’ one-way communications protocol.
Randy, Thanks for your quick reply. Your “Except they wired it backwards” still has me confused. All the wire instructions I see on the WifiTrax web site never gave me a hint of any ‘backwards’ situation like the LocoFi web site did. The LocoFi product seems to be totally different product than the WifiTrax product but you say there the same. my short coming. I will go back and look again at WifiTrax to find what I missed.
I think you took what he said out of context. He didn’t call you out personally, he was referring to the people like me that don’t want to spend the money on DCC. Never once did he attack DC or saying that it was behind in technology. All he said who the target audiance was and how the system is behind current DCC technology. Not how DCC is better than DC.
