# DCC Questions??



## edkedk (May 2, 2013)

I am new to this forum. I am planning a model railroad set-up and would like to use a wireless locomotive controller for about ½ dozen trains. A nice feature would be self- contained batteries in each train. I’ve seen this sort of design written up but do not have sufficient details for system design, set up or cost estimation.

Has any one used ac voltage applied to the rails to continuously charge a train battery or actually supply voltage to an on board dc power supply that drives the train. This type of set up would supply continuous dc voltage to the on board DCC locomotive controller when “dirty” track or when intermittent track supply voltage occurs.


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## D1566 (Jun 8, 2012)

What scale are you thinking of working in? Sounds like a complicated way of doing things ... why do you want onboard batteries?


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## Southern (Nov 17, 2008)

The cost of doing this to six trains would be more than keeping the track clean.

IMHO it is a wast of money


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## edkedk (May 2, 2013)

Are you comparing it to a DCC system or a basic track/block control system? The Dcc is there all I'm proposing is changing the power supply source!


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## Brakeman Jake (Mar 8, 2009)

Space in most locos is already at a preminm,so achieving your goal may be a bit complicated...but I suppose that a good electronician can design such system.The electronics aren't too bad as they can be made very small,like DCC decoders,but batteries that would have some autonomy may be a problem.

But then,I understand that your goal is to have some back-up power with dirty tracks and such but that's already dealt with.Visit "Train Control Systems" (TCS) and read about their Keep Alive decoders,they have capacitors that store power for shortages of up to 15 seconds.


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## Southern (Nov 17, 2008)

edkedk said:


> Are you comparing it to a DCC system


Yes, I see a DCC decoder in your drawing so I assume you are talking about DCC.



edkedk said:


> or a basic track/block control system?


By basic track/block, do you mean DC?



edkedk said:


> The DCC is there all I'm proposing is changing the power supply source!


Are you saying that you want to use a 24 volt sine wave (AC) instead of the DCC command station, Modified square wave?


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## broox (Apr 13, 2012)

what about a larger capacitor to handle the power fluctuations from dirty track?


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## edkedk (May 2, 2013)

I guess I have a few misconceptions about DCC. I thought the wireless throttle controller directly transmitted to the DCC control module in the locomotive. After a couple reads it is obvious that the throttle controller communicates it's info to a base unit connected to the tracks. A bummer, but workable. I still have not determined what type of "power" voltage is supplied to the tracks. Is it DC, full AC, half wave rectified AC, or full wave rectified AC? Or does it matter. I know the high frequency control signal is superimposed of the "Power" voltage.

Comments appreciated.


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## edkedk (May 2, 2013)

I guess I have a few misconceptions about DCC. I thought the wireless throttle controller directly transmitted to the DCC control module in the locomotive. After a couple reads it is obvious that the throttle controller communicates it's info to a base unit connected to the tracks. A bummer, but workable. I still have not determined what type of "power" voltage is supplied to the tracks. Is it DC, full AC, half wave rectified AC, or full wave rectified AC? Or does it matter. I know the high frequency control signal is superimposed of the "Power" voltage.

Comments appreciated.


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## DonR (Oct 18, 2012)

What we need here is a discussion of clean rails. 

If your tracks are cleaned before any operations
you will have no power pickup problems with your 
DCC locos. You don't need the type of circuitry
being discussed.

There are threads on the forum with suggestions of
how have good track hygiene. Check 'em out.

So, just relax and have the fun that a DCC layout offers. 

Don


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## Brakeman Jake (Mar 8, 2009)

I don't know if it will be of any help to you but I've read somewhere that DCC is in fact square wave AC current,pretty similar to what radio controlled models (planes,cars.etc) call PCM (Pulse Code Modulation).To what extent this is true,I personally can't tell but it makes sense to me.
Then the voltage varies.According to Digitrax's documentation,a DCS-100 command station sends 12V for N scale,15V for HO and then up to 20V for O & G scales.

Athearn offered a direct wireless control (handheld to train) in some of their models (N scale Big Boy and Challengers in occurence) that is used to control movement and some sounds in DC operation.In this case,the dual mode MRC decoders responded to signal using track power.These decoders have proven highly unreliable so have since been discontinued and replaced with Tsunami decoders wich I don't think have this feature.


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## waltr (Aug 15, 2011)

Look at the specs for DCC track power here:
http://www.nmra.org/standards/DCC/standards_rps/S-91-2004-07.pdf

Look at the remaining DCC specs to understand how the system works:
http://www.nmra.org/standards/sandrp/consist.html

Also, most DCC manufacturers and sellers have info on how DCC systems work so search and read.


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## edkedk (May 2, 2013)

I've read the NMRA stuff but have not found anything that simply says that the motor drive is one of the easily available voltages applied to the tracks; full AC, 1/2 wave DC, full wave DC or straight DC, (battery like). I don't care about the high frequency control signal that gets superimposed on to the motor drive voltage. My uneducated guess is that any but the full AC can easily be used and the preferred voltage is probably full wave AC.


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## Southern (Nov 17, 2008)

edkedk said:


> I've read the NMRA stuff but have not found anything that simply says that the motor drive is one of the easily available voltages applied to the tracks; full AC, 1/2 wave DC, full wave DC or straight DC, (battery like).


You will not.
The motor runs off of DC that is supplied from the decoder.



edkedk said:


> I don't care about the high frequency control signal that gets superimposed on to the motor drive voltage.


Good, because there is not a "motor drive voltage" on the track.



edkedk said:


> My uneducated guess is that any but the full AC can easily be used and the preferred voltage is probably full wave AC .


I am not sure what what you are trying to guess at. What do you mean by "full wave A/C".


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## Brakeman Jake (Mar 8, 2009)

The DCC decoder gets its power (AC) and instructions (DCC packets) from the track then in turn feeds rectified DC to the motor,varying voltage (0-12v) for speed and polarity for direction control.The motor never actually "sees" DCC current.


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## edkedk (May 2, 2013)

Back to the drawing board. It looks like the CRE57000SS REVOLUTION system, sold by Aristocraft does what I originally posted. A transmitter unit that directly communicates with an on board receiver to set train speed and direction, (plus some other features). What it does not say is can it start one train, then switch over to control a second, third, etc. train. All started trains should go at their set speeds and when the controller is switched to a train it's speed and direction can be controlled while the other trains remain running at their selected speed/direction. Not sure it will do this. Any one know?


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## Southern (Nov 17, 2008)

this is a good site for learning about DCC


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## NIMT (Jan 6, 2011)

What you want is right here:
http://www.tamvalleydepot.com/products/drs1wirelessdcc.html


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## broox (Apr 13, 2012)

I think Yak was looking into a setup like what your talking about, I know he has gone with regular dcc though.

i think, from memory, each loco had to have a seperate throttle... but thats just bad remembery


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## timlange3 (Jan 16, 2013)

Edkedk, there is another system I have used, don't know if it is still available though, it is an infrared system. Your handheld controller talked directly to the IR receiver in each engine. Track was just AC power, nothing else, no base station. A couple rotating dials allowed you to control any one of 99 engines at a time. Repeaters were available for long tunnels and hidden trackage.


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## feldon30 (Dec 30, 2012)

edkedk said:


> Has any one used ac voltage applied to the rails to continuously charge a train battery or actually supply voltage to an on board dc power supply that drives the train.


I can't imagine how this wouldn't cause serious problems and/or damage to a DCC system and locomotives.




edkedk said:


> I guess I have a few misconceptions about DCC. I thought the wireless throttle controller directly transmitted to the DCC control module in the locomotive. After a couple reads it is obvious that the throttle controller communicates it's info to a base unit connected to the tracks. A bummer, but workable. I still have not determined what type of "power" voltage is supplied to the tracks. Is it DC, full AC, half wave rectified AC, or full wave rectified AC?


It's a steady voltage DC squarewave but the wave is modified to "blip" a digital signal at 9600 baud. I don't think you want to do anything to disrupt the voltage or squarewave as you may lose communication with your engines or cause damage to the decoders inside them.


edkedk said:


> This type of set up would supply continuous dc voltage to the on board DCC locomotive controller when “dirty” track or when intermittent track supply voltage occurs.


If you are concerned about this issue and cannot clean the track/provide consistent power on your layout, a solution is to add a keepalive capacitor to each engine so that they can keep running for 1-3 seconds despite a short or power interruption.


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