# #4) Noise (Electronic) Prevention for [DCC]



## ED-RRR (Jun 4, 2015)

Regarding [DCC] power supplies.. 

In another thread in this forum
I mentioned about Noise (Electronic) when using [DCC]..
I was attacked by "Outdated" and "False" information against me..
Going to "Switching" V-DC power supplies has caused many problems.. 
Many of us old timers do not have this problem because we use V-AC ..

Caution:
This article will be very (very) confusing..
It will be very advanced for a vast majority..
I am doing this to show actual facts to prevent unproven attacks against me..

Warning: 
You can "not" use "ANY" switching power supply.. 

Information Is From:
- from Digitrax Manuals
- from Professional Electronic web sites
- from Electrical Engineers (x2)

=============================================

Warning:
Since all V-DC power supplies are now 
"switching" power supplies there are many [Different]
"types" of V-DC power supplies..
Each individual "switching" power supply
will be totally [Different].. 

When it comes to (switching power supplies)
I found many different types of "definitions"..
- Filtered
- Un-Filtered
- Commercial
- Commercial/Medical
- Medical
- Medical/Grounded 
- Ultra Low Noise
- Power Supply For Lighting LED's

=============================================

Switching Power Supplies: (Mark Gurries Friend)

Ed (ED-RRR)
I also am a electric engineer and many decades ago designed power supplies..
Do not be afraid to use switching power supplies from a "reputable" 
commercial source from the standpoint of "noise".. 
Switching power supplies seldom have [Isolation Transformers] like many older
analog power supplies so you need to be more careful of --> [Ground] !!
Follow the wiring rules Mark Gurries explains on his web site.. 
"MODERN" well designed switching power supplies are usually much more efficient
then analog supplies and do not cause electrical noise in the DCC frequency range..
From (Censored)..
He has a very large club HO model train layout 
using over (x10) Digitrax [DCC] units..

Digitrax [PS2012]
- Regulated "Switching" V-DC Power Supply "Transformer"
- 20.Amp maximum output
- Cooling Fan
- Release Date (2004) 
- Old (x11) years
- Unknown if it has an [Isolation Transformer]..
- Uses a [Ground] Wire.. 

NCE: [P1018]
Release Date 1990's..
18.V-AC @ 10.Amps
= "No" [Ground] Wire
= Still Being Sold..

=============================================

Definition: (Electrical Noise)

http://ecmweb.com/content/troubleshooting-electrical-noise-0

Electrical noise currents on data communication cables
are a real problem.. 
They can cause corruption of the desired signals being sent
across the cable by the equipment connected to its ends.. 
In extreme cases, these "Noise Currents" 
may even become great enough to cause electrical damage,
such as component burnout,
to the circuit elements used at either end of the cable.. 

=============================================

Question:
I can "not" find (x1) location on the internet 
that warns about using "switching" power supplies (noise)
from a [DCC] model train manufacture.. 

Answer: 
Mark Gurries:
Right and never will..

=============================================

https://en.wikipedia.org/wiki/Switched-mode_power_
supply#Advantages_and_disadvantages
- Electronic Noise 
- Electronic noise at the output terminals

Linear Power Supply:
Unregulated PSUS may have a little AC ripple superimposed upon 
the DC component at twice mains frequency (100–120 Hz). 

Switching Power Supply:
Noisier due to the switching frequency of the SMPS. 
An (Un-Filtered) output may cause glitches in digital circuits.

Question:
Why did the manufactures of power supplies "change" from
a V-DC power supply (Linear) to a V-DC (Switching) power supply ??

Answer: 
Mark Gurries:
Global Green initiatives have basically made 
switching power supplies the only choice going forward.. 
The labor cost on making old big iron AC transformers 
have also risen while the cost of switching power supplies 
which are mostly made by machines has fallen.. 
All of the DCC vendors have been forced to change the power
supply choices to switching power types to keep cost down
and conform to governmental green initiatives.. 
It not limited to DCC manufactures
for its a MUCH bigger problem affecting all manufactures..

=============================================

Digitrax:
SuperChiefXtra.pdf (File)
This rev 2.1 manual was updated 12/09. (2009)
* Section: 7.0 DCS100/200 Control Panel
* Section: 7.4 Ground Terminal
The terminal marked ground provides electrical safety features
and an [RF] ground reference for minimum radiated noise.. <-- LooK
(RF) = Radio Frequency.. 

Warning:
This is not good advice from Digitrax..
See below --> Ground: (Earth).. 

=============================================

Ground: (Earth)
Mark Gurries: (Electrical Engineer) and (NMRA DCC Clinic)

The key to controlling noise, is understanding where 
all the ground paths are and all the paths they take.. 
Ground loops are when there are TWO paths for 
the noisy current to flow between two points.. 
There is a saying that "Electricity will take the path 
with the least resistance, but that not 100% true.. 
Current flows in both paths all the time but the majority 
will be taking the path of least resistance.. It’s a ratio.. 
My point is that unless you know where your ground connections are going,
you have no control of where the current is going..
If you do not have control of the current path,
you do not have true control of system resulting 
in operational problems or worse..
Typically one of the paths is hidden or not obvious to the laymen 
which is why there is a mystery to the success or failure.. 

=============================================

LooK --> Improving DCC Reliability: 

Mark Gurries: 
https://sites.google.com/site/markgurries/home/
dcc-general-best-practices/booster-connections-power

=============================================

LooK --> Maximizing DCC Reliability:

Mark Gurries: 
https://sites.google.com/site/markgurries/home/
nmra-dcc-clinic-pdf-files
DCC Wiring NMRA.pdf --> (bottom of page) view/download 
--> NMRA = National Model Railroad Association.. 

Appendix: Section 2
Maximizing DCC Reliability
(requires special wiring)
(requires added capacitors) 

=============================================

Recommendations: (Switching Power Supply Used)

- Use a good (Trade Mark) V-DC switching power supply..
- It may have a [Ground] wire due to the metal case..
- Use a V-DC switching power supply rated for your purpose..
- Not a Commercial -or- Un-Filtered -or- For Lighting LED's..
- Avoiding using a [Ground] wire where possible..

=============================================

Warning:
Posted in "other" threads by me (ED-RRR)..

Digitrax "Minimum" Booster [Input] Voltage
[N] Booster Input = 12 + 1 => 13 volts
[HO] Booster Input = 14 + 1 => 15 volts 
[O/G] Booster Input = 18 + 1 => 19 volts 
......


----------



## ED-RRR (Jun 4, 2015)

*Commutator Noise Suppression*

Electronic Noise Reduction Techniques:

CTI Electronics: (Web Site) 
http://www.cti-electronics.com/

CTI Electronics: (Noise Reduction) 
http://www.cti-electronics.com/
Documents --> Electronic Noise Reduction Techniques..

Special Notes:
CTI Electronics: (Commutator Noise Suppression Capacitor) 
--> Look at picture posted = (#1A) Capacitor
--> Look at picture posted = (#1B) Capacitor
All motors are V-DC (current)..
Highly recommends to add a capacitor across every motor at the motor terminals to reduce arcing motor brushes..
Use a "small" 0.1uF capacitor..

Tortoise Switch Machines:
--> Look at picture posted = (#2) Tortoise
It is impossible to add a capacitor across the motor terminals due to lack of internal space..
CTI support informed me (E-mail) that adding a "small" 0.1uF capacitor
across the switch machine circuit board motor terminals [1] and [8] will help..

Walthers Turntables:
--> Look at picture posted = (#3A) Walthers
--> Look at picture posted = (#3B) Walthers
This only applies to turntables that have the electric indexing motor and a digital circuit board "inside" the turntable bridge..
The indexing electric motor with arcing motor brushes is right next to a digital circuit board [DCC]..
Going by CTI Electronics: (Commutator Noise Suppression Capacitor) 
you are recommended to add a "small" 0.1uF capacitor across the turntable indexing motor terminals..

......


----------



## wvgca (Jan 21, 2013)

the guidelines for spurious radiated electrical noise have changed over the last twenty years, and proper ground plane pcb design will give 'acceptable' S/N ratios as manufactured .. and most supplies do tie the enclosure to ground to assist this .. you can check your own components with a proper meter, or even an oscilliscope, also with an old am portable radio tuned between active frequencies ... or you always purchase a zero radiated noise 12v supply from walmart for maybe fifty bucks??


----------



## ED-RRR (Jun 4, 2015)

*12v supply*

Sorry, but I must do (x1) correction..



wvgca said:


> ... or you always purchase a zero radiated noise 12v supply from walmart for maybe fifty bucks??


In My:
DCC Forum (Digital Command Control) --> #1) Digitrax [DCC] "Minimum" Power Supply = 15.V-DC
Will also require 5 Amps.. 

I will be posting a "new" thread --> Digitrax Power Supplies..
......


----------



## wvgca (Jan 21, 2013)

Digitrax [and most other] DCC supplies, to feed the controller, are recommended to be 15v or better ... and this is based on the old DC recommended standard of having a minimum available 12v supply to feed the layout ... you lose 1.4v to the decoder bridge rectifier, and about the same again to the driver mosfets or h-bridge's .. so in the end the final voltage available is still a minimum 12v to the motor .. 
I wonder how many power supplies Digitrax has sold, It seems that I don't hear of very many failing on this , or other forums


----------



## ED-RRR (Jun 4, 2015)

*[DCC] Voltage Confusion*



wvgca said:


> Digitrax [and most other] DCC supplies, to feed the controller, are recommended<script id="gpt-impl-0.8571908598694777" src="http://partner.googleadservices.com/gpt/pubads_impl_75.js"></script> to be 15v or better ...


[wvgca]; :smilie_daumenpos:
In another thread in this forum I stated the "minimum" power supply is 15 Volts..
I was attacked with "outdated" Digitrax information..
Digitrax does "not" update their instruction manuals..
This is where all the confusion is..

KB326: DCS100 and DB150 - Power Supply
This article was last updated on April 11, 2012, 3:29 p.m. <-- LooK
http://www.digitrax.com/tsd/KB326/dcs100-and-db150-power-supply/








This year (2015) Digitax updated the information for all their Boosters 15 Volts "minimum"..



wvgca said:


> and this is based on the old DC recommended standard of having a minimum available 12v supply to feed the layout ... you lose 1.4v to the decoder bridge rectifier, and about the same again to the driver mosfets or h-bridge's .. so in the end the final voltage available is still a minimum 12v to the motor ..


You are correct..
As per N.M.R.A. [HO] scale DCC "decoders"..
As per N.M.R.A. [HO] scale DCC recommends 14.V-AC to the track..



wvgca said:


> I wonder how many power supplies Digitrax has sold, It seems that I don't hear of very many failing on this , or other forums


In (2011) Digitrax stopped manufacturing the [PS515] a very good strong power supply..



ED-RRR said:


> I will be posting a "new" thread --> Digitrax Power Supplies..
> ......


Must take in account of power supply voltage droppage when their is "no" reserve [Amperage]..
Must also take in account of a 1. volt drop through the Booster..
I will be pointing out that some 15.V-DC power supplies will "not" be sending the required "minimum" voltage [INPUT]..
(14.V Track) + (1.V Booster Drop ) + (1.5V Power Supply Drop) = 16.5 volts "minimum"..
......


----------



## wvgca (Jan 21, 2013)

there is no voltage drop through a booster .. it's a signal fed device .. however it is recommended that all boosters should be set to the same output voltage for the layout [ most are output voltage adjustable] and definitely in phase .. in very few cases a DCC system is loaded to full rated amperage, and when so the load is momentary and is not a cause for concern unless units are constantly going into thermal shutdown or other indications of SUSTAINED excessive load .. with newer locos that have sound, and super caps for reserve running power for example, startup amperage is higher, but only for several seconds when you turn the layout on ..and very few operators actually run at higher [say 9v applied to motor] voltages on a normal basis .. on my little layout I normally set two locos, Bachmann climax and shay with sound, to go round and round .. and use a 0-6-0 and a heisler to do some switching, with someplace under three amps total available ..over the years I have learned not to overthink 'what if', and enjoy 'good enough ..

..enjoy..


----------



## ED-RRR (Jun 4, 2015)

*Confusion*

Sorry, but we are going in circles..
Actual calculations and proof is required to prove a written "thread"..
We are also making it more confusing for everyone else..

Mark Gurries: (Electrical Engineer)
He advised me that there have been many (many) changes and "no" one knows it all..

Mark Gurries "Friend": (Electrical Engineer)
Some boosters such as Digitrax still have "inefficient" analog power regulators.. 
DCS100 5 Amp DCC Command Station & Booster..
Production Date = 01/27/1996 = Almost a (x20) year old design !!!


wvgca said:


> there is no voltage drop through a booster .. it's a signal fed device ..


Sorry, but I can not see an "old" designed Digitrax Booster operate at 100% efficiency to supply the "required" Track V-AC..
Converting V-DC into V-AC to power the "track" without "any" [VOLTAGE] loss..

Digitrax Booster = Minimum [Input] = 15 Volts.. 
N.M.R.A. [HO] scale Track [Voltage] = 14 Volts..
15 - 14 = 1 Volt Less 

Fact:
There will be different [Amps] and [Watts]..
-But-
The "track" [Voltage] must "always" remain the same for a [DCC] system to operate correctly.. 


wvgca said:


> ..over the years I have learned not to overthink 'what if', and enjoy 'good enough ..
> ..


The problem I have now seen that many individuals may "not" be getting the correct "track voltage"..
......


----------

