DCC Wiring: The Basics

Transcription

1 DCC Wiring: The Basics By Mark Gurries Presentations for NMRA & PCR Conventions V Free copies of this presentation can be found at: 1

2 Other Available DCC Clinics & Information See my website: DCC CLINICS: 1) DCC Basics Presentation (PDF) DCC system basics with review of various brands of systems available. 2) DCC Decoder Software (PDF) Decoder programming to set up your decoder for both basic and advanced operation. 3) DCC Decoder Hardware (PDF) Decoder installation basics. Selecting and wiring up your decoder. 4) DCC Wiring (PDF) (This Presentation) Information and tips on wiring your layout for maximum DCC performance. 2

3 Scope This presentation limits it s discussion to the most popular North American DCC Systems. However, most material is generic in nature and can be applied to other systems. About The Author Mark Gurries is a model railroader since 1973 and a DCC user since He is a professional Electrical Engineer who works in San Jose California (Silicon Valley). His expertise in Power Design & Management directly applies to DCC technology. Mark is also a NMRA and an Operations SIG member. DCC Wiring Mark Gurries Version 6.0 3

4 General Wiring DCC system overview Basic Wiring Topics (Part 1) DCC system components DCC wiring Cab bus Control Bus Wires Track Bus MINIMAL REQUIREMENTS / TEST Run Length Feeders Connections Reversing Sections» Reverse Loop» Wye s» Turntables MIXING DC AND DCC Advanced Wiring Topics (Part 2) DCC Wiring Mark Gurries Version 6.0 4

5 DCC System Electrical Overview (Simple) Simple Setup: Global power for all tracks Power Station (Booster) Command Station Cab Typically all packaged in one box 5

6 DCC System Electrical Overview (Large/Club) Accessory Decoder Switch Machine Local Bus Power Station (Booster) Block #1 Block #2 Block #3 Control Bus Cab #1 #2 Power Station (Booster) Track Bus Local Bus Circuit Breaker Circuit Breaker Auto Reverser Sometimes Integrated Reverse Loop Occupancy Detector Command Station Cab (feedback) bus Radio Base Radio Cab Computer 6

7 Simple DCC system setup (Booster) Different DCC systems contain and package ALL these bus and functions in different ways to meet cost versus flexibility goals.. Some bus or functions may not be directly accessible. 7

8 DCC Wiring/Cable Bus Definitions Definition of a Bus A group of wires that are used to distribute information or power. There are 4 DCC wire/cables buses to deal with. 1. Cab Bus The wires that go between the cab in you hand and the command station. 2. Control Bus The wires that go between the command station and the Boosters. This is for Advanced Layouts that use multiple boosters. 3. Track Bus The wires that go between the Booster/Power Station and your Track. 4. Local Bus Optional sub track bus with special purpose like occupancy detection. This is for Advanced Layouts using signaling. Each type of bus has its own unique cabling/connector system. Telephone, Coax, DIN, etc. There is also the AC/DC power bus wiring to consider. 8

9 Cab Bus: Walk-around types Cab Cab Power Supply Booster Command Station Most DCC systems support some level of walk-around cab control. Large systems/layouts typically are 100% walk-around. The wiring system is a distributive or Daisy Chain type. 9

10 Cab/Control Bus: Types of Wiring There is no DCC standard for DCC system connectors! The most popular connectors are those used by the telephone system call Modular Connectors. They use RJxx code names for types of connections. Brand: Bach mann Digitrax Easy DCC Lenz MRC NCE Zimo Cabus: (4 to 6 wires) RJ45 RJ12 RG58 Coax DIN RJ45 RJ12 RJ12 Control: (3 to 4 wires) 3mm Audio RJ12 RJ12 Wire RJ45 RJH Wire 10

11 Cab/Control Bus: Telco Modular Connectors Connector Naming: p = position c = contact Not Used In DCC! DCC Cab Bus Narrow Connector: Note: 4p4c is only used on NCE Control Bus RJH 4p4c (Phone Headset) 4 wire Cable RJ11 6p2c (Telephone) 2 wire Cable RJ14 6p4c (Telephone) 4 wire Cable RJ12 6p6c (Data Cable) 6 wire Cable Wider Cable! 11

12 Cab/Control Bus: Telco Cable Wiring Where to by Telco Cables ALL cables should be Pin to Pin (Pin1 to Pin1) Do not use a pre-wired telephone cable found at most stores!! Almost ALL have a reverse pin-out (Example: Pin1 to Pin6) Only use cables specifically labeled for Computer or Data. Many major internet DCC stores sell cable made to order. 12

13 Wiring: Defintions Wire: A single round metal conductor. It can be insulated or un-insulated. The most common metal conductor is copper. Wire Gauge: The size of the round metal wire. AWG means American Wire Gauge. Standardized US wire sizes and meanings. The higher the AWG number the SMALLER the wire. The lower the AWG number the LARGER the wire. Wire resistance per foot goes UP when the AWG goes UP and visa versa going down. Cable: Consist of two or more wires grouped together. The cable may or may-not have an outer jacket. Bus: A cable who s wires collectively perform a specific function. We often use the function name for the name of the bus. Booster Bus, Track Bus, Cab Bus, Accessory Bus, DC bus, AC bus Wire/Cable Length: The distance between point A to point B that you need to run the wire/cable between. Think about the actual wire path it must take as opposed to a straight line. 13

14 Two types of wires: Stranded Solid Wiring: Wire Types Both types of wire are interchangeable in terms of electrical performance. 12 AWG Stranded 18 AWG solid Physical Comparisons Solid wire is often smaller in diameter than stranded of the same wire gauge. Stranded Advantages: Flexibility allows easy installation. Optional easy twisting of two wires into a pair to make a flexible cable. 14

15 Track Bus: Minimum Requirements Coin Test Coin Test (Short Test) Minimum Requirement: Booster MUST shutdown when short occurs anywhere on the layout! Test for shorts using the Coin test. Short coin on every sectional piece of track on layout. Booster shutdown = good wiring Booster stays on = bad wiring. Why Test? Same as your old DC powerpack, except its always full on! Power levels almost 2X the power of a heavy Duty Soldering Iron. Compared to your old DC powerpack, your wires must now pass up to 4X the power. Bottom Line: it is a possible fire hazard with poor wiring!! 15

16 Track Bus: Run Length Keep track bus runs under 30Ft. No special wiring requirements Most layout are two small to worry about the 30ft wire length. This is why they work just fine. Why 30Ft? See appendix Booster What if I need more than 30Ft? Move booster to the middle of the track. Split track bus into to 30Ft sections going opposite directions from booster. This will give you up to 60Ft. 30Ft Booster 30Ft Want to maximize reliability? See appendix Length 60Ft 16

17 Track Bus: Track Feeders (1) Track Feeder Wire recommendations: Use #18 to #24 AWG stranded or solid. Track feeder should be less than 18 long (45cm). Reliability: Rail Joiners vs number of Track Feeders. The primary purpose of a rail joiner is rail to rail alignment. If they are made of metal, they also conduct electricity. Rail joiners are NOT a long term reliable electrical connection. The need for multiple track feeders is an indication you cannot count on them. The best long term solution for rail joiners is to solder them. Allow periodic unsoldered rail joiners for stress release. 17

18 Track Bus: Track Feeders (2) Unsoldered metal rail joiners will eventually fail electrically. Open circuit time bomb. Two reasons at work against you: 1. Hidden oxidation will form between the railjoiner and the rail. You cannot clean it with a bright-boy or other track cleaning devices. Resistance between the rail and joiner will grow with time. 2. Loose rail joiners are poor conductors or not at all. Any deformation of the railjoiner will reduce its metal to metal clamping force and contact area. Never re-use a rail joiner. Always use a new one. Deformed Unsoldered 18

19 Track Bus: Track Feeders (3) Unsoldered Rail joiner Track Feeder Recommendation A feeder tied to the track after every two sets of rail joints. Requires 2 rail joiners to fail in order for the middle section to loose power. Applies to both sectional or flex track. Applies to rail joiners with track feeders already connected. Center section with metal rail joiners on both ends is feed power from both ends 1 2 Track Bus Feeders Broken rail joiner: Center section still has power. Soldered Feeder Track Bus Feeders Rail joiner with feeder 19

20 Track Bus: Wire Connections There are two ways to make electrical wire connections. 1. Soldering 2. Solderless: Connectors Twist caps Crimp Lugs/Couplers, Terminal Block Insulation Displacement Connector (IDC): Suitcase Connector. Which method do you use? There is no wrong method. Choose the method that works for you. + = 20

21 Track Bus: Reverse Loops, Wye s, Turntables Note: Gap = Insulated joint or plastic rail joiners Old DC solutions still works! Reverse Loops, Wye s and Turntables all present track polarity issues. Same as found in regular DC power. Traditional solution is to add a manual reversing switch. DC solutions works just fine for DCC! DCC offers a way to ELIMINATE the reversing switch. No more manual operation of the reversing section required. 21

22 Relay Track Bus: DCC Autoreverse Solutions (1) Electronic DCC offers 2 devices to to replace that old switch: Auto-reversing Module: Two Module types. Relay & Electronic. They do not work with DC. Relay is not perfect. Slow: Some boosters will shutdown faster than relay can correct the short. Sensitive to layout wiring. Electronic solution is recognized as best. FAST! Auto-reversing Booster: Most expensive solution. But if you have a spare, it will work just fine. Recommended for large gauge. 22

23 Track Bus: DCC Autoreverse Solutions(2) Reverse Block Rules: Same rules as you had under old DC operation: 1) Length of reversing block track MUST be longer than the train your turning. 2) Double Gaps at ends of the reversing block. Turning Wye options: 1) Polarity controlled by contacts of Switch Machine. Throw machine sets polarity. DC method still works but sound equipped engines may die on slow contact switching. 2) Connect an Autoreverser to the Stub. Sound Equipped engines will not die on switchover. Turning Wye Reversing Block Insulated Joints Double Gaps Must be Longer than Train 23

24 Track Bus: DCC Autoreverse Solutions(3) Junction Wye Insulated Joints Double Gaps Must be Longer than Train Reversing Block is Turntable track itself. Wiring (double track<-> loop) Turntable Double Gaps are at Turntable Pit Edges. Note: Gap = Insulated Joint Reverse loop In Yellow Double gap both rails 24

25 Running DCC & DC on the same layout DC DCC* When DC and DCC come in contact: There is a Voltage Doubling effect. Will force hard short with full current!! Booster or Power Pack may WIN BUT You will LOSE! Need DCC To DC Protection BEST: Do not run both at same time! Once you TRY DCC, you ll never go back!! BETTER: Use DPDT Isolation Switch. DCC DC To Layout GOOD: DCC to DC power Circuit Breaker such as Lenz LT100 OK?: #1156 Car Lamp. But no guarantee it will work. * Polarity depends on Phase 25

26 Advanced Layout Wiring A given layout is considered advanced if it meets ANY of the following: 1. Larger than a 2 car garage. 2. Forced to use track bus wire runs over 30Ft. 3. Multiple Operators of many trains running simultaneously. 4. Scale is larger than HO (O scale/g scale) 5. Running lots of engines or lighted cars per train. 6. Signaling The above situations often leads to the need for: 1) more than 1 booster to run the layout 2) booster(s) that put out more than 5amps. 3) preventing a short circuit on the track from killing all DCC power. 4) High reliability wiring. 5) Rules for occupancy detections (Signalling) 26

27 Advance Topics Covered Advanced Wiring Power Districts Basics Insulating the rail. working with Multiple Boosters Multiple Boosters IDC Connectors Tools Solderless vs Solder Connections. A Model Railroader Achilles heel. Appendix DCC Wiring Mark Gurries Version

28 Advanced Wiring: Power Districts (1) DCC POWER PROBLEM: Global Power + Single short = Entire Layout shutdown!!! One Engineer = OK. Multiple engineers = No Good. DCC is less forgiving of small momentary shorts than DC. Most shorts occur around turnouts. Wheels are out of gauge!! Use your NMRA Gauge to check! Turnouts: Some types can present more challenges No Problem: Non Power Routing Type (Plastic/Dead Frog) Atlas, Elite Plitz, Peco Insulfrog, Roco, Tyco, New Walthers. Potential Problem: Power Routing types (Metal/Live Frog). Peco Electrofrog, old Shinohara, old Micro Engineering and hand laid. Trains run against turnout with powered frogs of wrong polarity = SHORT! Wheels of long wheel base locomotives touch back side of point rails = SHORT!» Turnout is to small for the Loco. Install larger # turnout or use smaller loco! The Point: Shorts happen and must be addressed on large layouts. DCC Wiring Mark Gurries Version

29 Advanced Wiring: Power Districts (2) SOLUTION: Divide up layout into Power Districts. A Power District: is a large functional section of track or track that is electrically isolated from other large functional sections of track goal is to isolate the short from the rest of the layout. minimize total layout power loss in the event of a short. Power Districts DC power blocks. DC Blocks = Keeping each train under 1 throttle s control! Do I need to rip up my DC Blocks on my old layout? No. You can keep them for fault trouble shooting or signaling. Just group your DC blocks into a single Power District. 29

30 Advanced Wiring: Power Districts (3) The Power District idea is the same idea as your Fuse or Circuit Breaker box on you house. Tripping one circuit breaker does not kill power to the whole house! Transformer (Booster) Circuit Breakers Power Devices or Districts 30

31 Advanced Wiring: Power Districts (4) Two Ways to create a Power Districts: 1. Use DCC electronic Circuit Breakers. Two types: 1. Relay: They work OK. Not great with sound decoders. 2. Solid State:» Most popular type» Faster and more reliable than relay.» Best are Sound Decoder Compatible» Address high inrush current problem» NCE EB1 & DCC specialties PSX series 2. Use Automotive light bulbs. Lowest cost. Most effective for N scale or smaller. Limit to low current (1Amp). Not recommended for HO or larger scales. Not good for lighted passenger trains Not good for MU/consisted powered locomotives. NOT RECOMMENDED FOR LARGE LAYOUTS 31

32 Advanced Wiring: Power Districts (5) LARGE LAYOUT Single 5A booster powers 4 power districts. A short in one will not effect the others. PD = Power District Isolating the track power into blocks allows more trains to operate. 32

33 Advanced Wiring: Power Districts & Insulating the Rails To create a division of power, you need insulated rail joiners. They can be purchased at any hobby shop. The term Gap comes from the visual description of what happens at the rail joint. The rails are separated by a air Gap Single Gap There are two types of gaps. Single Gap refers to one rail being gap d Double Gap refers to both rails being gap d. Double Gap The use of Single or Double gaps depends on how the layout is wired and what track features you have. Main Line: Only use Single Gap if you have common rail. Reverse Loops: Double Gaps are required. If you are in doubt of what type to use, then Double Gap. It works with any type of wiring or track situation you have. 33

34 Advanced Wiring: Power Districts & Multiple Boosters Large layout planning need Power Management terms. A DCC Circuit Breaker = Power District. A DCC Booster = Booster District. Why? Large club layouts can have multiple DCC boosters feeding multiple DCC circuit breakers. Booster Districts are placed to cover a operational area of the layout where the track bus run from the booster is approximately limited to a 30Ft run. Power Districts are defined to split up the booster power within the same operational area. They are INSIDE a given Booster District. Booster District 1 Booster District 2 Booster Booster DCC Circuit Breaker DCC Circuit Breaker DCC Circuit Breaker DCC Circuit Breaker DCC Circuit Breaker Notice Operational Track areas Power District 1 Yard Power District 2 Engine Facility Power District 3 Staging Power District 4 Main Line Power District 5 Branch Line 34

35 Advanced Wiring: Multiple Boosters (1) Rule: When dealing with multiple boosters in individual boxes, a heavy duty wire connection is required between every booster. Use same wire gauge as track bus wire gauge. This wire is above and beyond the normal control bus (booster bus) wiring. No wire means the following: Operational: Loco stuttering/stalling problems at power district boundary (Gaps) At a minimum the headlight will blink like dirty track. GUARANTEED stall if loco has offset electrical wheel pickup. Old Steam Locomotive pickup with Engine = Rail A & Tender = Rail B Electrical: Open Circuit path between boosters. Each booster s district is a Booster island unto itself. It does not know about it s next door neighbor booster s existence. Wire provides electrical path to allow boosters to see each other. Allows boosters to coordinate power transfer/handoff. => No Stall. 35

36 Advanced Wiring: Multiple Boosters (2) This wire goes by many names that for DCC are all the same: Ground, Home Ground (Digitrax term), Booster Ground & Chassis Ground Booster Common is technically the correct name. The question is: Which DCC systems require the wire? No Wire: Most small DCC Systems with current 3amps or less. Why? The Wire is integrated into the cables provided. Low booster current ratings allowing small wires to be used. Yes Wire: Digitrax, Lenz, NCE, & Zimo. Use heavy Gauge wire! Terminal Labeled Ground Lenz Terminal E 36

37 Advanced Wiring: IDC Connectors (1) Example Tap ScotchLok 3M Wire Taps: Fast Crimp based connections Alternative to soldering. Use large electrician pliers to crimp. Flip-over tab covers tap and insulates. Makes gas tight oxygen free metal to metal connection. Two Types of Connections. Tap Only Tap/Run 37

38 Model # Advanced Wiring: IDC Connectors (2) Picture Primary Wire AWG Minimum Track Wire Primary Wire AWG Maximum Primary Wire Type 3M AWG stranded or solid 10 AWG stranded only 3M Stranded or Solid 3M Stranded or Solid. 14 AWG Stranded Only 3M Stranded or Solid 3M Stranded or Solid Secondary Wire AWG Minimum Feeder Wire Secondary Wire AWG Maximum Secondary Wire Type AWG stranded or solid 10 AWG stranded only Stranded or Solid Stranded or Solid. 14 AWG Stranded Only Stranded or Solid Stranded or Solid Secondary Connection Type Tap/Run Tap Tap/Run Tap/Run Tap Connector Color Yellow Brown Blue Red Red Primary Wire Secondary Wire Recommendations: 567 for Advanced Layouts. 905 for small home layouts 38

39 Advanced Wiring: IDC Tools 3M ScotchLok Professional IDC Tool Sale ~ $70 1 hand operation. High crimp leverage action. Confortable wide grip. Physical stop lets you know when your done. Fastest Tool for the Job. 1. Crimp: Push blade down into wires. 2. Flip cover over 3. Finish crimp. Cover locks automatically. Preset jaw positions matched to specific IDC sizes Monkey Wrench = Monkey Crimp if not careful 1-2 hand operation. Adjusting Jaw to closest size that works with IDC Jaw size IDC size Bulky long tool can slip out of hand Low crimp leverage action may require both hands. Slow productivity Potential Incomplete under Crimp. No physical stop related to needs IDC size Loose wires inside IDC. Blade not fully engaged with wires. Poor electrical connection. Not gas tight. Not full metal to metal. 39

40 Advanced Wiring: Crimp Tools Sale ~ $ AWG Ideal # Ratcheting Type (# Tool = # Frame + # Die) Crimp is a fast reliable method of making electrical connections. The biggest reason crimps connections fail is due to improper crimping. The key to success is to use a the proper tool such as a Ratchet Crimp Tool. Perfect crimps every time. You get what you pay for!! The tool shown above handles wire sizes from 10AWG to 22AWG. Color coded crimp slots match the color of the insulated crimp lugs. 40

41 Soldering vs Solderless Connectors Why do some say only soldering is the way to go? Solderless connectors have RIGID rules regarding their installation procedure and usage. Failure to follow them can result in a less than reliable connection in the long run. Ticking Time bomb. Model railroaders seldom follow the rules for several reasons. Do not know what the rules are. Do not believe they need to follow the rules. They know better. They do not want to buy the proper tools to save money. Solder Only People Swear they will never use a solderless connector again. Possible past history trouble shooting an electrical problem only to find it was a solderless connection failure. Rather blame the connector instead of themselves for not following the rules. KEY POINT: THE COMMERCIAL ELECTRONICS INDUSTRY USES SOLDERLESS CONNECTORS ALMOST EXCLUSIVELY WITHOUT A CONNECTOR FAILURE. Computers, tablets, consumer electronics ect... 41

42 Appendix 1) Making Your Own Cab Bus cables 2) Maximizing DCC Reliability. 3) Proposal: A modular flexible layout wiring system 4) Special Wiring rules for current based Occupancy Detectors used in signaling. 5) A methodical approach to calculating your layout s total booster current requirements. 6) Wire Commons. 7) Information about RJ telephone wiring system. 8) Revision history. 42

43 APPENDIX: SECTION 1 MAKING YOUR OWN TELCO CABLES FOR THROTTLE / CAB BUS CONTROL BUS 43

44 Cab/Control Bus: Making Your Own Cables (1) There are two types of Telco RJ connectors: Stranded & Solid. Very difficult to tell by just looking at the connectors. Stranded is the most common connector type (along with the wire) Solid is used in commercial (CAT-5 type) installations. MESSAGE: Use the right connector with the right wire! 44

45 Cab/Control Bus: Making Your Own Cables (2) RJ12 Pin 1 to Pin 1 RJH Pin 1 to Pin 1 45

46 Cab/Control Bus: Making Your Own Cables (3) RJ11/12 Expensive $50 RJ11,12 & RJ45 Ratcheting Type Best Swappable Connector insert 4p or 6p Cut & Strip AVOID You Get What You Pay For! Radio Shack <-- Cheap $10 RJH,11,12 (Discontinued?) Pro version=$30 46

47 Cab/Control Bus: Making Your Own Cables (4) Says: RJ11 + RJ45 Basic Model: NS-468 Shanghai-Yiyang-Electronics-Co-Ltd. Test Your Cables!! Unreliable connections are the hardest to find and cause the most problems! Buy a 6 wire (3 pair) tester. Green light means pin to pin!! Correct. No light means cable is bad. Wrong. WIRE TUG TEST: Tug/Pull back on cable Tug/Pull cable to side. Check for light blink or light dies. 47

48 APPENDIX: SECTION 2 MAXIMIZING DCC RELIABILITY 48

49 Advanced Wiring: Maximizing DCC Reliability (1) DCC Track power consist of 2 parts combined. They are: 1. power to run the train. It is a form of AC. It is not DC. 2. digital commands. Used to command all decoders. Decoders must have clean strong DCC signal for reliable operation. Distortion/noise of DCC signal can prevent acceptance of the digital command by the decoder. Command lost. Command station has no idea if the decoder got the DCC command or not. What does this mean to you if it gets bad? Loss of decoder control of one form or another. Partial Control: Engine works in one direction on the track but does not work at all going the other way. Momentary loss of control on some portions of the layout.» Appears to be a runaway at current speed. Loss of all decoder function after a track (derailments). Engine takes off at full speed. Engine requires reset & re-programming to get it to work properly again. Decoder blows up Who let the smoke out. 49

50 Advanced Wiring: Maximizing DCC Reliability (2) How does the track wiring cause these problems? Wires have other electrical properties other than simple resistance (ohms). Wire Inductance (Impedance) is the parameter causing problems. You do not know about them because they are not ACTIVE with DC power. They become active with DCC (AC power). What does Inductance do? They create distortion and corruption of the DCC signal. What controls the magnitude of the distortion? Proportional to the wire length of the track bus. Longer is worse. Proportional to the booster s current rating. Higher is worse. What action creates it? Intermittent action of wheel to rail contact. (Open Circuit) Any short on the track. (Short Circuit) Excessively long track bus wiring. 50

51 Advanced Wiring: Maximizing DCC Reliability (3) How do we reduce the track bus cable/wire inductance? Using a track bus cable that pairs up the Rail A and Rail B wire side by side as close as possible to each other without shorting. Like: Lamp cord Speaker wire Twisted Pair cable. Reduces the wire inductance Address the root cause of the problem. Reduces Electrical Noise and Voltage Spikes on the track under high current. Will not completely eliminate the problem due to wire constructions limitations. 51

52 Advanced Wiring: Maximizing DCC Reliability (4) Best wiring practice for track bus: Make you own twisted pair cable. Use the wire gauge you want. Use a wire color code combination you want. Allows multiple track bus to be run side by side but easily identified which is which. Identifies the Rail A wire vs Rail B wire.» Same as track polarity. A twist every 2-3 is good. More twist is electrically better. Twisting eats up cable length.» Cut wire 15% longer than the run lenght. Do not recommend using Lamp Cord or Speaker wire. Monochromatic cable will not help you physically wire up the layout. Will cause wiring installation problems. Not worth the money you save. 52

53 Advanced Wiring: Maximizing DCC Reliability (5) Making your own Twisted Track Bus Wires Only needed if track bus run exceeds 30Ft. Use variable speed drill and a vise/hook. Pull two stranded wires of same AWG and desired color code. Tie one end of cable to vise or hook in wall. Use a knot. Do not worry if it messes up the wire. It will be cut off. Pulling against vise or hook, stretch wires side by side and keep them tight parallel to each other exactly same length. Cut to length adding 15% more to your length requirement. Lay them down side by side on the floor. Insert lose end of cable into chuck of drill. Keep wire length equal. Pick up drill and pull cable tight so it is suspended in air. Spin drill a very low speed. Let the twist move down the cable. Over tighten twist by 3x. Be carful. Upon release from drill chuck, cable will unwind violently. Cut off damaged ends of the wire. 53

54 Advanced Wiring: Maximizing DCC Reliability (6) The science behind the DCC noise and voltage spike problem. Momentary Shorts on the track create Voltage spikes. How? Sudden high change in current flow + natural inductance of wires creates ADDITIONAL voltage. Electrical Law: V = L x I/ t where:» V = Voltage created by inductance» L = Inductance of the wire carrying the current» I = Value Change in current level for any reason (Short Circuit)» t= Value Change in time the current took to change its value. Inductance voltage ADDS TO the track voltage. Rides on top If inductance voltage is strong enough, it can: Exceed the maximum voltage rating of the decoder. Minimum: Cause the decoder to forget it settings and require reprogramming. Worse Case: Literally blow up decoder do to electrical overstress of the electronics. 54

55 Advanced Wiring: Maximizing DCC Reliability (7) See the inductance effect in action on the DCC Signal. Photos below shows it effect even with nothing happening! No trains running = No high current flowing. There is no significant energy in these voltage spikes. Measured at Booster s DCC Terminals. Measured at end of a 25ft track bus. More images can be found on: <-Normal DCC Signal of 14.4V (28.8 Peak) > Noisy DCC Signal with a 70V peak spike! Ouch! 55

56 Advanced Wiring: Maximizing DCC Reliability (1) Solution: Build RC track noise filters (bus terminators).! Consist of a capacitor (0.1uF) & a resistor (100Ω 1/2W) wired in series.! Absorb noise and voltage spikes without effecting the DCC signal itself.! Place at opposite end of the track bus wiring relative to booster location. Think far end or end of the line.! More information can be found at: 56

57 APPENDIX: SECTION 3 A MODULAR LAYOUT WIRING SYSTEM ALLOWS YOU TO BUILD A LAYOUT FASTER AND HAVE CONSISTENCY 57

58 Advanced Wiring: Modular Track Bus Example (1) Definition/Rules: Bus: A group of wires that combined perform a specific electrical function. Track Bus (Backbone): Global power linear distribution bus. Has tap point for local bus every 8 feet using barrier strips. No direct connection to track is allowed. Located in the back away from the Cab Bus. Tap Point: Allows easy insertion of power control or monitoring devices. Circuit Breakers, Occupancy Detections, AutoReverser Local bus: A small local bus limited to powering a single track block Track feeds wires are tied to this bus. Track Block: Any section of track that needs to be electrically isolated to support power districts, block occupancy, or any section of track needing special power considerations. 58

59 Advanced Wiring: Modular Track Bus Example (2) Power District Track Feeder Track Bus example shows 3 Power Districts: 1) Main #1 Red/Blk 2) Main #2 Org/Blu 3) Accessory Yel/Brn Local Bus Booster (With 3 Power Districts) Backbone Tap Point 8 Feet 59

60 APPENDIX: SECTION 4 SPECIAL WIRING RULES FOR CURRENT SENSING BLOCK DETECTORS USED IN SIGNALLING 60

61 Advanced Wiring: Signalling Track Feeders Block 1 Block 2 Block 3 Track Track Track RC Filter Main Bus (Twisted Pair) Untwisted Local Bus Block Detector Booster or DCC Circuit Breaker Occupancy Detection (For signals) Local Bus AFTER DETECTOR CANNOT have twisted wiring. DCC signal can leak between wire and show FALSE occupancy. Keep wire spaces apart by at least 1/2 Less capacitance between wires when separated. No track filters on this side of Detector. 61

62 APPENDIX: SECTION 5 A METHODICAL APPROACH TO CALCULATING YOUR LAYOUT S TOTAL BOOSTER CURRENT REQUIREMENTS. 62

63 System: Determining DCC Layout Power You need to add up all the current in Amperes (A) of all the loads LOADS: POWER STATION 63

64 System: Determining DCC Layout Power Only needed for large layouts that can run lots of trains. Most Starter System have enough power for typical layouts! Procedure to figure out your power budget: 1) Add up total maximum engine current. Determine maximum number of simultaneous operating engines. Determine motor current per engine. Don t know? Use: N=1/2Amp, HO=3/4Amp, S=1.5Amp, O = 4Amps 2) Add up total maximum rolling stock accessory current. Determine maximum current for all lighted passenger cars or cabooses. Determine current for each car. Don t Know? 14V bulb = 30mA/Each, LED s = 20mA/Each, 3) Add up total maximum Stationary accessory current. Determine maximum current for Switch Machines, Signals & Building Lights. 4) Divide the total current by the booster current rating to figure out the number of boosters you will need. 64

65 System: Determining DCC Layout Power (Example) 1) Add up total maximum engine current: Max engine current = 7 HO engines ay 3/4A (0.75) each (7 x 0.75A = 5.25Amps) 2) Add up total maximum rolling stock accessory current: 7 Cars with five 30mA bulbs in each car is 1.05Amps. (7 x 5 x 0.030A = 1.05Amps) 3) Add up total maximum Stationary accessory current: 50 x 10mA turnout stall motors. (50 x 0.01A = 0.5A) 100 x 30mA street lights 100 x 0.03A = 3A (3A + 0.5A = 3.5 Amps) 4) Sum up all the above currents Amps Amps + 3.5Amps = 9.8Amps 65

66 System: Determining DCC Layout Power (Example) Take sum of layout current and divide by the current rating of one power station (booster). (Assumes all boosters are the same) Example: Power Station current rating is 4Amps 9.8A / 4A = 2.45 boosters. Round Up to the nearest whole number > 3 Boosters. Cost Cut: Move street lights to a 12V AC/DC power. Determine new booster current: 9.8A - 3A = 6.8 Amps. 6.8A / 4A = 1.7A -> 2 Boosters. What about buying a single 8A or greater booster? ONLY IF you plan to use Circuit Breakers to drop the effective current going to each section of track (Power Districts) to 5 Amps or less. Why? To much current and small scale engines wires = burned wires. These boosters were originally intended to run large scale of O or larger. Has the side benefit of also saving money. 66

67 APPENDIX: SECTION 6 WIRE COMMONS DEFINITION AND PROPER USAGE 67

68 DEFINTIONS Wiring: Commons and DCC (1) Common: An electrical point in a system that is shared by many electrical devices. It s purpose is to establish a common (shared) electrical voltage reference point so every device connected to it can work together to allow power or signals (information) to flow freely between them. Common Voltage: A common can be any voltage we want it to be. Voltage = 0V. This is what is called a Common Ground for the circuit in question. Ground does not mean Earth Ground. Only Earth Ground is TRUE 0V. Only Earth Ground is global. Circuit ground is local to the circuit using it. A given electrical system can have more than one common ground. Voltage NOT 0V. Common Power, AKA a power source, is often simply called Power. It is local to the circuit using it just like circuit ground. The voltage value is often use as the name for the power source. A given electrical system can have more than one common power source 68

69 Examples of Commons: A Decoders BLUE wire is 12V or a Hot Common for engine lights. Planet Earth is a HUGE common called Earth Ground The green GROUND wire in US household 240/120V wiring serves at the Earth Ground common. Most electrical circuits have a common ground and common power inside. Booster Common: Wiring: Commons and DCC (2) Used by boosters to share power between them at Power District boundaries to coordinate smooth crossing of trains. The white NUETRAL wire for any US household 240/120V circuit is a common. 69

70 There are 3 types of commons possible in DCC for track power: Common Rail (Used on large DC layouts to save wire.) Booster Common (DCC preferred) Power Supply Common. (Shared Power supply) Not recommended with DCC. Potential Hazards Which one to use? Wiring: Commons and DCC (3) Do you even know what Common Rail is? YES: Use boosters design for Common Rail. Use Optical Isolated Control/Booster Bus inputs NO: Then you do not need to know. Use Booster Common. Follow Booster s Instructions for connecting multiple boosters Only ONE type of common is allowed in a DCC system. Pick one and stick with it! Using more than one can cause problems or even damage. 70

71 Common Rail A Common Rail system has one track rail which is never gapped or electrically broken. Rail is followed by and fed by a single BIG wire bus running around the layout. An advanced popular wiring system for large layouts in DC days. It cuts the amount of track wiring down by 1/2! Booster Connection: Wiring Commons: Common Rail One Power Transformer per booster. Connect one side of every booster track output to common rail bus wire. Use boosters with Optical Isolated Control Bus inputs. NCE, Lenz, EasyDCC s PowerZone Digitrax requires special order. Do not use Auto-reversing mode of booster if offered. Reverse loop function will not work. Will result in double voltage on track! MUST use Reversing Module instead. Common Rail Gap Gap <---No Gaps---> Note: Gap = Insulated Joint 71

72 Wiring Commons: Booster Common Booster Common or Home Ground. Common developed inside the booster/power station. Booster Connections: One Power Supply per Booster. Install Booster Common per Manufacture instructions. Some boosters have a dedicated terminals to do this. Some boosters simply need their metal chassis (case) connected together. Some boosters have integrated it into provided cables to make this connection. Connect outputs directly to tracks within this booster Power district,. Advantages: Recommended by all DCC manufactures. Compatible with all boosters made today. Compatible with Auto Reversing boosters. Easily supports the traditional Point to Point layout wiring system. Disadvantages: Does not reduce layout wiring. 72

73 APPENDIX: SECTION 7 TELEPHONE RJ DESIGNTIONS FOR REFERENCE ONLY 73

74 What with this Telco RJ stuff? (1) RJ stands for Registered Jack under FCC Part 68 Telephony rules. The connectors and jack we use today are part of the MODULAR phone connection system developed by AMP corporation. They are not part of the FCC rules. RJxx describes a type of FCC regulated telephone service connection. It does NOT define a specific connector. Today the industry uses Modular. It does NOT allow for wire reversals. All connections are pin to pin. It does define the number of wires and the pin number location. Description of service is found in the FCC rules part 68 Manufactures of RJ connectors use a #p#c definition for cable connection. #p = Max # of possible connections. #c = Actual # of wires connected. Examples: RJ11 is a single phone service. It is a 6p2c connector with Pin3=Tip, Pin4= Ring. RJ14 is a dual phone service. It is a 6p4c connector with pins 2R,3T,4R, & 5T used. 74

75 What with this Telco RJ stuff? (2) Some RJ numbers are made up and not FCC registered. RJ12 appears to be a network industry definition for 6p6c Data connection. RJH or Headset Jack appears to be a practical description of 4p4c connection. Also known as RJ9 and RJ22 but no one in the consumer market has heard of these numbers. There is a lot of BAD information out there & the part industry pushes it not knowing better. You cannot use common Modular Telephone Cables with DCC systems. Why? Your every day telephone modular cable does not follow FCC standards. Why? Pin to Pin connection is not followed. The lack of consistent cable manufacturing prevents achieving compatibility with DCC wiring requirements You can make cheaper 100% function telephone cables WITHOUT following the FCC standard. No Pin to Pin cable requirement means cable production manufacturing and testing is simpler and faster. How is this possible? The modular cable pin out for a telephone cable is that it must be wired symmetrically about the center line of the cable to reduce wiring mistakes.» There is no DC polarity issue. RJ14 example:» Pin 2 & 3 = Pin 3 & 2 = telephone line #1» Pin 1 & 4 = Pin 4 & 1 = telephone line #2 Why?» Accidentally flipping/reversing the wires about the center line does not cause any loss of telephone line function. Hence telephone lines do not care about the pin-out just as along as the cable is symmetrical. 75

76 Convention Revision History V 1.0 PCR mini 9/13/98 V 1.0 NMRA 2000 (Updated PCR) V 2.0 PCR & NMRA 2003 V 3.0 PCR 2006 V 4.0 NMRA 2007 V 5.0 NMRA 2008 V 5.1 PCR 2009 V 5.2 NMRA 2011 V 6.0 NMRA 2015 EXTRA 2011 NMRA DCC Wiring Mark Gurries Version

77 Advanced Wiring: Wiring Topologies (types) There are two basic forms of wiring up a layout: Daisy Chain Just like the wires on the Telephone poles. Single long wire that carries cab bus to all cab panels. Efficient use of wire. Throttle/Cab Bus Example Point to Point or Star Uses lots of wire. Easy to trouble shoot. One locations for everything. Best practice for creating power districts within a booster district. Circuit Breaker Circuit Breaker Booster Circuit Breaker Central Location Long cables out to track 77