DC Knowledge sought

Model Railroader Electronics and DCC
1

I’m building a spare room sized HO railroad. This’ll be my first layout in a long time, though I’ve been in the hobby on and off since I was a kid 45 years ago. I’m wiring it DC, since one of my goals is to become more familiar with electronics. I’ve found some nice throttles online I can build.

Here’s my question for you all. Are there any of you with extensive DC experience that would be willing to correspond and act as my “Yoda”? I’ve been viewing posts on this forum for some time and there are a number of people who are straight DC proponents and whose knowledge would be very helpful.

For those who feel the need to advise me to go DCC, I have to quote the erstwhile governor of the great State of Alaska…Thenks but no thenks!

Lou

2

What type of help are you looking for? I’ve built my own throttles for my own use and the club I’m in. Do you have any knowledge or experience in electronics? I was trained in the Air Force as an Electronics Technician.

3

Lou

Feel free to contact me via PM or e-mail.

I would also recommend you consider buying a book on DC wiring from our hosts (Andy Sperando’s Easy Model Railroad Wiring, available at your LHS or here: http://www.kalmbachstore.com/modeltrains-railroading-model-railroading-books-wiring-electronics.html). Buying a used book on model railraod wiring such as Linn Westcott’s or Paul Mallery’s would be equally effective. I recommend books for those who have a hard time creating a schematic in their minds from a prose description (almost all of us). I learn better with visual aids like diagrams and photos - especially a subject like wiring. Replicating the excellent diagrams in the books in e-mail or on-line is very time-consuming, considering my limited computer graphic skills. And the books more thoroughly discuss a given topic then e-mail replies can hope to do.

I will be glad to help out with specific issues that a given book glosses over or doesn’t address. My assistance won’t be at the level of Sheldon’s automated DC systems - the level I would be at would be power-routing turnouts, blocking schemes for operations, and perhaps some limited relay logic. This is all I’ve needed for my small DC layouts. I think I still have most of the original MR articles (in the late '50s) on Route Cab Control and Progressive Cab Control to refer to if need be. I’m not sure whether or not I have the Ravenscroft articles on MZL DC control if you were thinking of that path - I believe these appeared in the '70s.

Here’s a picture of a very simple handheld throttle I built in 1976 using an MR article for circuit ideas. I adpated the circuit to 2 pieces so the power transistor was under the layout.

4

Hunt up a copy of Linn Westcott’s How to Wire Your Model Railroad and give it a good read-through. It was written pre-DCC, in plain English with lots of diagrams.

I wouldn’t make a good guru - I just might pull a Yoda and die on you. Also, while I do use analog DC, it’s modified MZL system and bears about the same resemblance to basic cab control that a high-tech yacht bears to a rowing dinghy. That leaves me like the pianist who can handle Chopin’s most complex fingering, but has to stop and think about Chopsticks.

Chuck (Modeling Central Japan in September, 1964)

5

Hiya Guys.

Thanks for the timely responses.

Tom, my experience is pretty limited. Built a few Tandy kits as a kid, know how to read a (basic) schematic and know which end of the soldering iron NOT to hold on to. I’m still struggling with the idea that to get a 5 ohm resistor you can parallel two 10’s. I still have to get a diagram to keep the relationships in Ohm’s Law straight. If whacked enough times with a 2 x 4, I can still learn.

Fred, making my own throttles is one of my main goals. I’d love to build Westcott’s TAT-IV throttle or something similar that offers some adjustability for start voltage, top voltage, pulse width and cutoff and so on. I’ve found some decent looking ones online (but not the TAT-IV) and they don’t look too confusing.

Chuck, I should have mentioned in my OP that I’ve got Andy S’s book “Easy Model Railroad Wiring” (if that’s the correct title). Good book, well written and pretty clear. I do understand that basics of block wiring, common rail, reversing sections, x-sections and so on. I’m just looking to build and use some of the more refined developments in straight DC.

I know I’ll get advice to “drink the kool-aid” and go DCC. I do down at the LHS (except from the owner). After watching the guys at the LHS spend all Saturday afternoon taking the shell on and off, tweaking the CV’s, looking up fixes online and just generally cussing up a storm, I don’t think I’ll dance w/ that girl. I’d just as soon “control the track” as “control the controller”. [swg]

All of you who offered, or are offering help, I appreciate it. I’ll PM or email you if I get stuck. One of the nicest things about this hobby is the willingness of the more experienced to help out the less experienced among us. I’d like to offer my experience as a machinist of 40 years to any of my colleagues who could use it.

Tha

6

Count me in for help if you need it. Just PM or email me.

Have you tried this site for throttle projects and other model RR projects?

http://home.cogeco.ca/~rpaisley4/

(Sorry, I don’t know how to paste in a link.)

7

HI Bob,

Thanks for the offer. Yeah, I’ve checked out the site. Not bad, but I’ve found some more intrigueing to me.

Lou

8

The below photo should show you how to link your site or any other site. I could not remove the underline. It is not needed.

Rich

If not clear enough. Left bracket url right bracket address left bracket forward slash url right bracket

Note; No spaces between anything.

9

Lou,

You have been offered help by some of the very brightest minds on here, Fred, Chuck and Tom are all great DC minds, even if they are modest.

Like Chuck, I use a somewhat advanced DC system, based on some of the same concepts Chuck uses.

I too would be more than happy to help in any way possible. Feel free to PM or E-mail any questions you have.

Sheldon

10

Lou

The circuits for the TAT IV throttle appeared in Model Railroader in 1969 (I lost the issue in my last move, when the post office lost a couple of boxes of bound MR volumes on me). There weren’t all that many built, but those who did build it reported it as one of the best throttles ever. The problem is finding the components forty years later. It would take some redesign to use today’s available components. Kieth Gutierrez of CVP (maker of CVP DCC equipment) might have better insight into this issue. The other issue with the TAT IV was the learning curve of the interdependencies of the various controls - very much like optimizing a Tsunami decoder with all its CVs. One later adaptation was once you had tuned the throttle for a particular locomotive, the settings were recorded in a small plug that would be inserted into the throttle when you ran that particular engine.

The other question to consider in DC throttles (since you or building or customizing your own) is what I call “control style”. Do you want a tet

11

There was one final update to the TAT line with the TAT V which repalced the discrete components with integrated circuit op amps. Either one will probably require some experimentation as many of the specified components will be unavailable. And while the TAT throttles do some neat stuff, they still output a basic DC varying voltage with pulses mixed in - the PWM method used in newer designs like the Aristo system provides better motor control. I guess the ultimate would be TAT controls putputing PWM to the rails. True BEMF is also possible. Actually, the way to do it these days, it to use a microcontroller like a PIC or ATMEL to do all the ‘math’ part handled by the array of op amps in the TAT design, although I suppose that goes against the ‘simplicity’ of DC control. It’s just a lot more versatile - depending ont he chip used and how much you want to build you can have varying performance controls depending on engine type and how much train it’s supposed to be pulling - like the reistor packs used in the TAT V that modified throttle performance. Check out the Yahoo Model Railroad Electronic group.

SInce Fred brought it up - ALL of the performance characteristics you could want to modify are in all but the crappiest DCC decoders. And you’re not limited to what the manufacturer provides - if you don’t buy a closed system! I point you to the FRED throttles for Loconet, home made controllers with varying features depending on what you want to add. Digitrax is probably the only system that truly allows this as they freely publish the information you need to make a throttle for their system - none of the others does. With JMRI you can add any desired control device for any system supported - basically all major brnads except MRC. The first such device is the WiThrottle app for iPhone/iPod Touch. Such a concept with an intermediary app to handle the translation would also work in a DC environment, if desired.

&n

12

Randy brings up a very good point. The motor control capabilities of a DC throttle and the DCC throttle/decoder combination can be exactly the same. If you took the decoder out of the locomotive and mounted it in the throttle or under the layout, and hook the orange and gray motor wires to the track instead of the DCC system, you would have a pulse width modulation (PWM) DC throttle.

PWM is pretty much standard in DCC as the method to control the motor because it works quite well, but more importantly is efficient - PWM doesn’t generate much waste heat to deal with in the confines of a decoder.

There are PWM circuits for DC throttles that are reasonable to build and use readily available components. They are also available as kits and already built. The main catch - and this was a problem for early DCC decoders too - is using a sufficiently high pulse frequency to avoid motor growling and possible overheating of coreless motors. Some PWM DC throttle circuits use 60Hz as their pulse frequency because it doesn’t require additional circuitry to generate a higher freq. But as “Silent Drive” and similar DCC decoders have shown, boosting the pulse frequency to above 1KHz gets rid of the problems without sacrificing much in tie creeping ability. Incorporation of BEMF makes slow speed operation even steadier and smoother.

Now a DC throttle doesn’t have to worry about efficiency and heat so much - we can mount heat sinks as needed, or as in the case of MRC’s ControlMaster 20, use cooling fans. So we are not restricted to PWM as the motor control method. Personally, I prefer pulses to start dying out and being replaced by filtered DC as the motor gets above 6 volts. I feel this is a little kinder and easier on motors. But that’s my personal choice.

As I said before, by building your own, you can select what you want in a throttle.

my thoughts, your choices

Fred W

13

Granted, it is not a kit like the OP expressed interest in, but since he may not be aware, I will mention that the Aristo Craft Train Engineer wireless radio throttles I use are Pulse Width Modulation throttles and are high freq. with no motor hum and no over heating issues.

The resulting motor control is excelent, and standard DC lighting effects provide excelent constant lighting features.

Sheldon

14

Sheldon,

I am using the Aristo Craft Basic (one train) Train Engineer until such time when I upgrade to something else, if ever. It works wonderfully. I am very happy with it as it suits my priorities so far.

Not to hijack the thread, but it might be interesting for the OP to have a bit more information on the constant lighting statement. Its my experience that the lighting does not work well for all locomotives. It seems to work best on certain locomotives and not so well on others. I run only diesel. It works best on early to mid 2000 run Proto’s and Atlas Classic’s. The newer run P1k GP15 not so well. The Atlas’s with the dual mode decoder, even set to the factory default DC setting, the lights do not even come on at all, which is not the case when I use to run those locomotives on the basic power supply/throttle. I’m using a standard Railpower 1370 for powering the Train Engineer, but I believe the differences lie in the PC Board’s of the locomotives. It looks like manufacturer’s change the circuitry of those board’s from time to time, and not just when making them DCC ready. The boards on the Atlas Classic’s changed over the years, but even a 2008 run of the U23B and the RS-11, the lighting works great, as you described. It does not work very well on a 2007 run of an RS-1. Both are classics, but the lighting operates differently.

In my situation, the Aristo Craft product improves the

15

Hi All Y’all,

I’m learning already, which was the goal all along. Even though I don’t think I’ll require wireless (my room’s 11’ sq) knowing that high frequency pulses are less troublesome than 60hz pulses is useful info for me as I dig through throttle plans. I’ve found some that do “dissolve” the pulses out gradually like the MRC power packs do. The one I’m using now, a Railpower 1400 is a basic unit but it will allow all my engines to creep very well. One thing that tells me is that my basic requirements are not exotic at all, and a throttle with memory/walkaround capability but otherwise fairly simple will fill the bill. I know I could buy a kit, but with my desire to DIY I think I’ll just gather some parts and build one. I’ve already got a 12.6v. center tapped transformer I bought some time back for another project.

I think the idea of using a decoder to control what is otherwise a DC layout is a novel idea. Seldom do you get a chance to tick off two diametrically opposed parties at once![}:)] The DC guys would say you’ve over complicated the whole deal, and the DCC guys would accuse you of not taking advantage of the medium. Seriously though, I do like the degree of control offered, but wouldn’t you have to use a large scale decoder or would a basic HO decoder work once you figured out how to link it to a layout? It’s a clever idea in any case.

Thanks to all for providing so much food for thought.

Lou

16

Doug,

First I would excude ANY dual mode decoder equiped locos from my statement. I have found all decoders to be problematic with the Train Engineer in pulse width mode and/or my detection and signaling system. So I remove all decoders, or don’t buy locos with them in the first place unless the price is right.

Second, some DC locos wired for DCC, like BLI BlueLine, do not have correct lighting effects on any DC throttle with the “jumpers” installed.

I do not have the Proto1000 GP15, as it is out of my era, but even my brand new DC Proto2000 F7’s work just fine.

And, I will admit to not having any Atlas locos since little of what they offer is in my 1954 era.

On a few locos I have had to remove the niose filter capacitor on the jumper board to get good slow speed, but this does not effect the lighting.

Also, while we are here, I remove the motor filter capacitors on ALL Bachmann Spectrum locos and this provides MUCH betterslow speed performance with the Train Engineer. Easily as good or better than any decoder installation I have seen in a Spectrum loco.

I have over 100 locos, Bachmann Spectrum, Proto2000/1000 of all ages/production runs, Genesis, Intermountain, old Athearn w/upgraded motors, Mantua, IHC, BLI/PCM stealth, BLI with the sound/DCC removed, they all work fine.

Since I have no plan for DCC and no interest in collecting or reselling, I modify the few that need such, but all the DC products I have tried work fine, no so with dual mode decoders.

Sheldon

17

This is certainly doable. I don’t know of anyone who regularly runs like this, but I do know of some people who have their layout setup so that they can switch the layout between the DCC output and the output from the decoder. They use the decoder output setup to test run new engines before installing decoders in them. As far as the current requirements for the decoder, it would depend on how many engines you run at a time and the current draw of those engines. My biggest concern with doing a layout this way is most decoders are not designed to withstand a short on their motor outputs, and since occasional shorts are common on most any layout, I think it would be wise to include some sort of short protection between the decoder and the layout.

18

Lou

Going a little astray: It was an illustration - although feasible - to show that DCC and DC are not as different as conventional thinking would indicate. If you look at DC and DCC as black boxes, the inputs and outputs are the same. The “engineer” provides inputs as to what he wants the locomotive to do, and the system puts out a shaped power form to our DC motor that makes it perform the desired action.

Where the 2 really differ is where the power form shaping takes place. DCC puts a decoder in the locomotive to perform the power form shaping. And it adds addressing so that only the selected locomotive takes action. The rails only conduct data communications and the raw power source. Sound and lights are also generated locally as additional outputs from the decoder.

A DC throttle performs all the power form shaping upstream, and puts the finished output on the rails. Thus a subsystem is needed (track blocking) to ensure only the desired locomotive gets the throttle output. If the throttle and controller are separate boxes, an addressing scheme and comms link are needed to connect the controller and throttle. This can be as simple as a 3 wire tether or a full blown wireless throttle bus as in some DC

19

Thanks Sheldon,

Yes, lighting effects with the Train Engineer works great with all of my proto’s, except the GP15, which also tends to have a jack rabbit start as well. It works well with the few Athearn’s I have. I only have proto, Athearn, and Atlas.

I figured the dual mode decoder was an impedement, but I bought those locomotives before I bought the CRES

20

Hi there lou, I have started to build a HO 4x8 layout. If I buy a DCC ready engine will I be able to rum it on regular DC one day? Is DCC worth the price even considering saving all the wireing?? Harry E-mail hstapper@shaw.ca