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DC braking in a DCC system.

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DC braking in a DCC system.
Posted by Anonymous on Sunday, November 19, 2006 6:00 PM

I don't know if anyone knows much about this subject but i would like to try to find out more about it if i can; does anyone have any idea where i could look please,

The idea is that you reset CV 29 from the factory set "4" to "0" and this makes the locomotive work only on DCC and not on analogue. You the block wire a section of your track so that it can have either DCC or DC on it. If it has DC your locomotive will brake to a stop in an orderly fashion as conrolled by the setting in CV 3 and when DCC is reapplied it will accelorate away as per the inertia in CV 4.

Any advice please or any idea where i can find out more about this fascinationg subject?

Rgds Ian  

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Posted by cacole on Monday, November 20, 2006 10:42 AM

I don't think so -- going from a DCC to DC block would cause an electrical short circuit and is likely to create smoke where it's not welcome.  There's no CV that can be reset to accomplish what you envision -- it's either DCC or DC, but neither the twain shall meet.

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Posted by Anonymous on Monday, November 20, 2006 10:48 AM

iandor;  read your post with keen interest and especially the reply.  I know nothing at all about DC or DCC operations so would like to ask you a question -

Explaine the difference between DC and DCC and can any G-scale engine be converted to run on one or the other?  I plan to use a Bachmann Big Hauler Engine in my layout.  Do you know if it can be converted to DC power and if so, how?

Many thanks.

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Posted by GearDrivenSteam on Monday, November 20, 2006 11:33 AM
I'm leaning toward cacole on this. Randy Rinker is a very sharp guy on DCC on the MRR general forum. You might try posting it there to his attention. His answer, I would bank on.
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Posted by Anonymous on Monday, November 20, 2006 5:57 PM

Cacole and Robert as much as i like and respect you two blokes, i must tell you in this instance you are incorrect; as i have already done it. Thanks for the advice on this other bloke Robert, i will look into it.

My problem is that, when switching to DC for braking, when your loco is programmed for DCC running only and this DC braking is a pre set function. But it seems to me to be in my instance very reliant on polarity and as i have designed and built my own PCB (printed circuit board) it is really hard for me to reverse polarity.

As well, would this polarity effect be altered epending on which way i enter the block that will have DCC or DC on it? I will only want it to work going from east to west and the other wouldn't come into effect anyway.I have actually made two of these devices and i suspect the polarity required may be different in each case.

Those blokes who reckoned i was out of my league in the section over DCS MTH are remarkably absent from this discussion;. i would love to hear from them and we will soon see who is out of there league and who isn't.

To conclude, this does work and although i would rather do my braking in assymetrical manner i would need to replace all my decoders some 15 of them with Lenz Gold ie about A$1,500.00.

Rgds ian

 

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Posted by Anonymous on Monday, November 20, 2006 6:20 PM

I am sorry SRS i forgot about you; a DC system is what nearly everyone has and it is these days also called an analogue system. You supply DC (Direct Current) across the rails and this will conrol thew direction and speed of any locomotive across those rails. DCC is to to with digital control and the idea is that you have full voltage across every part of you layout all the time and you control what your locomative or other accessories do via "little parcels" of information that are sent out digitally across these same rails. I have forgotten exactly what DCC stands for as i do many things these days; i am sure some one will pipe up very shortly with the inforamtion.

DCC is by for the most effective and versatile system but it is also the most expensive to get into initially; if you wish to get into it the earlier the better; as in the long run it willbe less expensive and less labout intensive, as your layout gets bigger and more complex.

Most people do not get into digital for a few reasons 1) more expensive to set up 2) harder to understand; for instance the LGB MTS instructions are initially virtually ununderstandable in my opinion. 3) Many people especially older ones like me are Xenophobic (fear of new information and ideas).

I have 6 locos, several have more than one driving section and 8 points (switches) 4 signals and they are all remotely actuated by MTS DCC control. I can run all of my locos at once (i don't because i smash them up all the time through not concentrating properly) and these locos can be all made to do different things at the same time on the same track. I have no block wiring and all parts of my layout are live all the time.

Not only this but MTS remembers your layout and adjusts the throttle of the loco to allow for gradients (both up and down) and dirty track etc.

Rgds ian 

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Posted by GearDrivenSteam on Monday, November 20, 2006 8:45 PM
Cool Ian. I like when I'm wrong. That's when I learn the most. LOL
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Posted by Anonymous on Monday, November 20, 2006 10:03 PM
Gentlemen,

Yes, DC braking on DCC works. Google has answers.  One explanation is this.

BTW an even more elegant solution is the ABC system  which uses an asymetrical signal in the block section.

Hope that helps, the information came from the desk of our techie.

Best regards

ER

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Posted by cacole on Tuesday, November 21, 2006 8:45 AM
Well, as they say, you learn something new every day.  In the HO scale world, DCC users have always been warned against ever attempting anything like this for fear of destroying a decoder.  I know that many decoders are now dual-mode, so maybe that is why it can be done.
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Posted by GearDrivenSteam on Tuesday, November 21, 2006 10:45 AM
I just handle it very simply. My On30 DCC layout will stay DCC, and my large scale micro layout will stay DC. I have to have it simple. I'm too stupid to have it otherwise. LOL
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Posted by Anonymous on Tuesday, November 21, 2006 6:03 PM

I found out about DC braking on a DCC sytem from Fred Hughes at DCCBitswitch. He told me how to conduct some tests to see if my LGB decoder equipped stuf would work. I had to reprogramed my Mallet, mainly "CV 29" from "4" which is factory set and gives 14 step control on both digital and DC to "0"  which gives the same thing only for digital though and i had a bit of trouble but eventually i got it to work. This is what i am going touse for economical reasons though i don't think it is the best solution by a long chalk. You can do a lot with this by adjusting the inertia within your loco by adjusting CV3 (acceleration) and CV 4 (braking).

Look at page 4 of DCCBitswitch's catalogue and he covers the 3 most popular means of automatic braking. 1) Set speed Zero packet. 2) Asymmetric DCC and 3) Analogue DC.

In my opinion asymmetric is the way to go but you need to have all your locos fitted with Lenz gold decoders or similar. I think zero speed packet is what LGB use (I could be wrong) and it is a good system but you need a dedicated power booster (a few hundred $ each from LGB) for every sector that you wish to fit out. I have 2 sectors at this stage but this could grow to about a dozen before i am finished. So like the rest of us i am not made of money.

This is why i advise everyone who is going to get into DCC to do it early but be very careful what you do. If i had my time over agin i would have LENZ gold right through but to change now is prohibitive. And the same goes for buying locos that are not all that suitable for DCC operation and then regretting it.

I cannot speak highly enough of the above gentlemen, very careful, very technical and very honest. After several weeks of negotiation he told me he couldn't help me, as my layout is a true bidirectional one.

Look up DCCBitswitch on google.

Rgds ian

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Posted by Anonymous on Tuesday, November 21, 2006 9:44 PM
Dear Ian,

More notes from our techie.

The method of DC braking for DCC control has been around for quite some time. The pioneer for the method, as applied to model trains, is UMELEC of Switzerland. ATLplus can handle bi-directional traffic on single track lines.

The ABC system requires decoders which can process the signal that is used. Some of the ZIMO decoders can handle the ABC mode along with the much more advanced ZIMO mode.

Currently there is a group of DCC manufacturers working on bi-directional communication protocols, this will be the next step in better DCC train control.

Best regards

ER


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Posted by Anonymous on Wednesday, November 22, 2006 6:00 PM

This method of using DC to automatically invoke a braking action is ok for me but tome it seems to be a backward step. But as they say money speaks all languages and it works and is cheap and easy to do.

Rgds ian

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