LOL Jim,
That’ll teach you to be careful what you say to the press! [swg]
Seriously though. Would not the use of negative (-) and positive (+) clarify things considerably? Whether it’s technically correct or not isn’t the point since it’s clear there is already no standard terminology. The point is to standardize something universal that common folk already understand.
Bruce Webster
HA! HA! HA! That’s nothing compared to the guy who asked “How do you wind up that thing?”
Regards,
John O
That’s funny…I always thought that this stuff was run by smoke…Every time the smoke comes out of the wires, nothing works…[:D]
When one is talking about low voltage output, toy train, post war transformers, they are talking about transformers, not case problems in “E” engineering school. In CTT Neil is trying to communicate with a general population of o-gaugers and is rightly using certain terminology that although perhaps technically incorrect has become routine useage.
The common conductor from a toy train transformer is in fact a return to complete a working circuit. It ain’t a “floating ground” or a “neutral” although it does share characteristics with the household neutral which is also in fact, a return. Peter Riddle author of three volumes of “Wiring Your Lionel Layout” has used the term “ground” consistently and incorrectly in his books. However he and other authors have effectively served to assist many o-gaugers with their work just as CTT is doing with their articles. It is important for entry o-gaugers to know the alternative terminology just as it is to remind them of the technically correct terms.
Many equally learned and practicing professionals use “neutral” as an alternative to “common” in toy train discussion and in actual component labeling as Lou Kovach did with the Track power Controllers.
This has all the makings of a D**b Blond Joke. Good that we can all have a little laugh. Thanks,
Dennis
Count me in as one of the electrically challenged. I understand the basics but some of the things people share go over my head and I have no reference point in which to ground (so to speak) what is shared.
I’m still trying to figure out how to use the soldering methods shared on the forum to plug the holes in the end of the track on my dead end sidings so that watts don’t dribble out. After all my transformer only has so many of them…
Sometimes I wish that technical articles contained a glossary of terms.
I remember when I switched over to three rail O gauge and read something to the effect of “connect the wire to the transformer’s common”, I had no idea what that was. I had one starter transformer that wasn’t labeled - it had one terminal with a metal screw and one with a plastic screw. Then I was given a KW and everything was labeled with letters! I finally figured that if there were two “U” posts, and one “A” and one “B”, then the “U” must be “Common”. After all it was the most “common” letter used…
Then I started to get some books that explained how to use transformers, wire layouts, etc. the basics began to fall into place. When I fried my first smoke unit during a train crash I knew I was getting somewhere. Yes, a little knowledge is dangerous. (Now I have in-line fuses.)
I still get lost in some of the technical posts on the forum - such as Bob’s most recent response in the thread on O22 switches where he is explaining “inductive load”. I understood the word “arc”, but phrasing such as “when you open an inductive circuit, the rate of change of current is infinite–it stops immediately” seem like a philosophical contradiction to me.
I like the technical explanations and accurate wording, but I often need a very very simplified example to illustrate them.
Chris
Now if you could come up with a wireless battery charger, that would be a great system![;)]
Bruce, the fact is that there is standard terminology. The problem I see is that that terminology is not only not understood by many, but also misunderstood in various ways by readers who lack knowledge of the underlying physical and engineering principles. The challenge as I see it is to use the right terms (which do exist) in such a way that we can teach an understanding of those principles adequate to solve the toy-train-running problems.
For example, I must respectfully disagree with your suggestion to use the term positive or negative somehow as a substitute for “common”. This implies that the polarity of a DC voltage has something to do with the concept of a common return. This is not “something universal that common folk already understand”, but rather something they misunderstand. I think that this, far from clarifying anything, would only confuse those who haven’t thought about it and confirm erroneous ideas for those who have.
Bob,
Please excuse my ignorance on the subject. It is obvious by my post that I only understand the basic facts and misunderstand more than I’d like to admit. It’s clear I over simplify things to fit what I don’t understand and I end up sounding like one of those who believes electricity pours off the ends of open rails. I appologize for confusing anyone with my ramblings.
Thanks for your patience on the subject. I really do appreciate you taking the time to set me straight.
Bruce Webster
Bruce, you need only look at the almost total lack of anything resembling scenery on my layout to realize that everyone here has something he doesn’t understand or do well. The strength of the forum is that we can help each other out with what we do understand, so that everyone comes out better off.
[#ditto]
Bob has helped me a lot [and I know a lot about basic wiring]. Sometimes I have to say, “Bob splain it to me in English.” Then he knows I have to have it broken down to learner’s level.
I think we’re making mountains out of molehills here. The terms “common” and “ground” have been used for years by toy train electricians and as long as everyone understands its application to toy trains, then I don’t see what the problem is. A socket for example is a female part to both pipe fitters and bone doctors. To a doctor a socket is the female part where bones connect. To a pipe fitter it is part of a pipe fitting where a pipe is inserted and welded. Who is in error here?..nobody really. It’s the same jargon used by different trades to mean different things.
Interesting discussion but I feel it is mostly about semantics. The term “ground” was commonly interchanged with “common” by engineers years ago before grounded 3 prong plugs were common place. Earth ground,a wire connected to copper plumbing or a stake driven into the ground was not used much in schematics.
In phonograph amplifiers for example, schematics have 2 symbols for ground,“chassis ground” and “signal ground”,neither which is connected to a true earth ground. The term “ground” is used in the context of the domain of the device. It is normally something connected to a large body such as a metal chassis. In the circuit for a car for example, the car body is used as a common return but often refered in the schematics as “ground”. Wires connecting the battery,chassis and body are refered to as “grounding straps” ,at least they were years ago. In the context of the schematic,it is understood the car sits on rubber tires and it is not a true earth ground.
With the advent of 3 prong plugs,schematics and terminology have been made clearer and meanings have been clarified to refelct a true earth ground. The terminology has changed I guess, as has a lot of common words. “queer” used to mean odd “gay” used to mean light and fun ect. When using these terms with younger people it reveals your age and you sound out of date. The same type terminology applies to the PW ZW transformer. Since it has a 2 prong, non polarized plug ground and common are used interchangably because it is in context of terminology years ago.
The only important thing is that the user understand it. On my layout I use green wire for a common return with the understanding it is not a true earth ground. In summary you have to put things in context. When Bill Clinton was asked under oath if he was ever “alone” with Monica, “alone” had to be clearly defined. Yes they were “alone” in the room but outside the room down the hall were people and there were guards at the front gate. So they were alone in the room b
There are actually three standard symbols for ground-common type things: The “common” symbol is an open triangle whose only significance is that it is connected to all other like symbols. There is an option to put a distinguishing character inside it if more than one common is needed. The “chassis” symbol is a horizontal line with several short diagonal lines dangling from it and represents a connection to the box that the equipment is in. The “ground” symbol is several horizontal lines that would fit into a triangle and means an actual connection to the earth or, the one exception, the frame of a vehicle.
There is, to be sure, a lot of loose usage that confuses all three of these concepts with each other. This does not mean that the distinctions among them are unimportant or useless. A schematic diagram that misuses them may be understood if the reader correctly guesses what actual connections are meant. I feel that it is better to use the standard symbols and terminology than to rely on the inferences of the reader.
But none of this addresses the use of the word “neutral” in the magazine, which is to my mind a more serious offence, on the order of calling any electrical problem a “short”. It oversimplifies a useful concept, the neutral, to the point that we lose the name for it in order to provide another synonym for the already conflated terms “common” and “ground”, in the same way that we lose the ability to clearly distinguish a short circuit from other faults when that term means “any failure” to the reader.
May I add the observation that since the discussion of ground, common, neutral, etc. is entirely about what these words mean, it is of course about semantics. This does not however mean that it is not worthy of discussion.
I think you’re agreeing with me, Dale, that tripling the capacitor’s voltage rating is
Except it isn’t. Joe and I have corresponded a lot over the past couple of years, and he actually shared this circuit with me long before this article was published in CTT. In one of his initial designs, he used a 35v cap, and he found it was getting too hot. When he stepped up to 50v, the cap stayed cool.
I’ll say it again. Joe actually tried this circuit with a 35v cap and he didn’t like the results.
Space indeed is limited in this application, but excess heat is also a concern, and heat in tight quarters is an even bigger concern.
Dale Hz stated that using a too-large capacitor isn’t a problem. This weekend, after I saw this thread, I asked an old friend of mine who is also an EE if there would be anything wrong with using one that large. He said no.
Having read a story of a trolley bursting into flames in the very pages of this magazine within the past year or so, I’ll gladly cast my vote with Joe Rampolla on over-engineering the solution, rather than going with the minimum that gets you by. I’d rather spend a few extra dollars up front to have something that runs cooler and lasts longer.
My 8th grade science text book had a picture of a train layout with a single break in the rails of an oval, and the caption that the train wouldn’t run because the circuit wasn’t complete. My 9th grade text book had a simmilar picture. Both years, there was also a test question regarding this. I was given the benefit of the doubt in 8th grade(since the teacher knew me well enough to know what I was talking about). In 9th grade, I missed the question despite the fact that I even set up a point-to-point track on one of the lab benches to prove my point.
The presumption was always that there had to be a complete oval for the train to run, which of course we all know is not the case.
Please note that I did not say that there is anything wrong from an electrical point of view in using an overrated capacitor, only that it was a waste of space.
A 35-volt capacitor should be good for 35 volts. This is the peak voltage when the RMS voltage is 25 volts, as much as a type-Z transformer puts out. I can think of some possible explanations for why one would get hot:
It wasn’t really a 35-volt capacitor. It could have been defective from the start; or it could have been old. An electrolytic capacitor with time loses its ability to withstand voltage if it is not used at that voltage for a few years. (They can be “re-formed” and put back into shape.)
The peak voltage was higher than 35 volts. A phase-control transformer (like the CW80) can put out a high peak voltage even when set for a modest RMS voltage. However, 35 volts peak is more even than the CW80 puts out.
Whether one of these is the explanation, I don’t know. But the practice of using an aluminum electrolytic at or near its rated working voltage is well established and is not considered at all risky. An analogy with mechanical engineering: If a bolt fails, you might triple its diameter to get a margin of safety; but tripling its length won’t accomplish anything.
It occurs to me to add that all of my locomotives are converted to DC, with rectifiers and filter capacitors. Because of space limitations, many of these are rated as low as 16 volts (I have a boxful, salvaged from old equipment at a former job), with the expectation that I would replace them until I got ones that I could form to work at the somewhat higher actual voltage. So far, they don’t overheat and none have failed.
Hello Bob:
Why do you use DC?
Regards,
John O
I agree with Bobs analysis.
No way should a 35 volt capacitor burn up feeding 12-20 volts in. Capacitors were most likely defective,believe me this happens. Not all 35 volt capacitors are equal either. Some are rated at 105 degree centigrade and some at 85 degree centigrade. real old ones do not even have specs. If a 100 volt capacitor is substituted in its place it will become just as hot because it will do the same amount of work. Increased voltage rating by itself would not offer further protection. Modern capacitors are so much better than the old ones from the 50s.,which could go bad just sitting on a shelf and leaked even when new…
I rebuilt many amplifiers in the 1980s and 1990s and I cant stress the importance enough of using fresh name brand capacitors. I never had one I rebuilt come back or have a failure.
As far as the semantics I am an old fuddy duddy so I guess I am used to misapplication of terms.
Dale Hz
Erotica???[}:)][}:)][}:)][}:)][}:)]
WoW!!! I have to start paying more attention to CTT!!!
underworld[:D][:D][:D][:D][:D]