signal systems in model railroading handouts/c467_albers ac... · placard team digital dbd2™...

AC-DC-DCC

AC-DC-DCC4_blue.ppt x 8/1/2012 Slide 1

AC-DC-DCC


NOTE

This Clinic Is Highly Animated With Picture Overlays And Graphics.

PDF and Other Versions May Look Contaminated.

AC-DC-DCC


AC-DC-DCC

ByDr. Gerry Albers

NMRA Life MemberCincinnati Div. 7, MCR

With Examples from the Author’s

Deepwater District, Virginian Railway

Photo credits: Gerry Albers, Clinician

AC-DC-DCC


Deepwater District - Virginian Railway

Deepwater DistrictNew River Division

Virginian Railway

1600 Sq. Ft.

11 Hidden Staging Yards

49 Staging Tracks

AC-DC-DCC


Introduction (Stuff I Wish Someone Had Told Me)

AC-DC-DCC


• DC (Batteries)• DC From AC

– Half Wave, Full Wave– Unfiltered, Filtered

• DCC (A Square Form of AC)• DCC Layout Wiring

– Device Hierarchy, System Architectures– Detector Wiring, Characteristics– Switch Wiring– Multiple DCC “Track” Buses

• Neat (Cool/Tidy) Wiring Practices– Color Codes, Wires Sizes– IDC Connectors– Strap Gun Usage– Miscellaneous Stuff

• DCC Cab Buses – The Differences– Master/Slave vs. Peer-to-Peer

Preparing For Signals

Overview

“Take Aways”: Practical Information and Useful Tips

Vendor Independent

AC-DC-DCC


DC From Batteries – Purest Form

• “Bagdad Battery” probably the first.Used for electroplating gold ontosilver objects (~ 200 BC – 200 AD).

• “Voltaic pile” invented by the Italian physicist Alessandro Volta in 1800.

• “Battery” coined by Benjamin Franklinfor an arrangement of multiple Leydenjars.

• Railroads used batteries for telegraphand signals.

• Modern hybrid locomotives employlarge arrays of batteries

• Model Railroad Uses– E.G., Wireless Throttles

Bagdad Battery

NASA Publication

Symbol

Nickel Metal

Hydride (NiMH)

Rechargeable

AC-DC-DCC


Oscilloscope Trace

AC Basics

• 22.3 Volts Peak

• 44.6 Volts Peak-to-Peak

• 15.8 Volts AC RMS*

• 0 V DC

• 16.6 milliseconds per cycle

• 60 Hertz (cycles per second)(1/.0166 = 60)• *RMS: “Route Mean Square” (Square root of the

mean of the sum of the squares)

• Also known as “Effective Voltage”

• RMS = 0.707 * Peak (for sinusoidal waveforms only)

DMM(Meter)

120 VAC

60 Hertz

14 VAC

@1.14A1000 Ohms

GND

IN

MeasuringDevice*

* Digital Multi-Meter (DMM) or Oscilloscope

15.8V

1000= I = .016 A

V

R

For a Transformer:

The rated voltage is only

valid at the rated current.

Clock Timing

15.8VDC 15.8 VAC RMS

AC-DC-DCC


Oscilloscope Trace

Half Wave DC

• 21.6 Volts Peak (22.3V - 0.7V)

• 8.3 Volts AC RMS

• 6.7 Volts DCDMM (Meter)

120 VAC14 VAC

@1.14A1000 Ohms

GND

IN

0.7V

A Diode (Half Wave Rectifier):

• Increases the DC component

• Decreases AC component

+

+AnodeCathode

Diode

Light Emitting

Diodes (LED)

Produce Light

AC-DC-DCC


Oscilloscope Trace

Full Wave DC

• 20.9 Volts Peak (22.3V – 1.4V)



AC

+14 VAC

@1.14A

1000Ohms

GND

IN

AC

A Full Wave Rectifier:


• Decreases the AC component

Bridge Rectifier

AC-DC-DCC


Oscilloscope Trace

Full Wave, Filtered DC

• 20.9 Volts Peak (22.3V – 1.4V)



AC

+14 VAC

@1.14A

1000Ohms

GND

IN

AC

10 µf

A Filter Capacitor:


• Decreases AC component

AC-DC-DCC


AC vs. DCC

AC provides:

• Power

• Accurate Timing (60 Hertz)

DCC provides:

• Power (Square AC)

• Information (1’s & 0’s)

Oscilloscope Trace Oscilloscope Trace

1/60 Sec.

“1” “0”

~14V

(14 VAC)

AC DCC

NMRA RP9.2

Use “AC” Setting on DMM

AC-DC-DCC


Power Hierarchy – Home Wiring Analogy

TransformerCircuit

Breaker/Disconnect

120/240V

200A

~7,500V

CB Panel

120/240V Ground FaultOutlet(GFCI)120V

20A

Similar To DCC Booster

Similar ToPower District

Circuit Breakers

Circuit Breaker-

Disconnect

AC-DC-DCC


P1DP1CP1BP1A

DCC Device Hierarchy

DCCBooster

& CB

DCCBooster

& CB

Control Bus (or LocoNet)

DCC

Circuit

Breaker(S)

DCC

Circuit

Breaker(S)

DCC

Circuit

Breaker(S)

DCC

Circuit

Breaker(S)

Track Bus (DCC)

PowerSupply

PowerSupply

PowerSupply

Cab Bus(or LocoNet)

DCCCommand

Station

Throttles

(Cabs)T T T

Ground!

(Consult Manual)

5 Amp

8 Amp

Power Supply > Booster

Gap Both Rails

Only OneAs Many As Needed

Power

District

Definition

P1 P2

Switch Both Rails

Keep Same Polarity

Booster Near Track

Fan (12VDC) Fan (12VDC)

Fan (12VDC)

Magna Force

MF615

MCM

Electronics

AC-DC-DCC


DCC Track Wiring

DCC Rail A (12 ga. stranded)

DCC Rail B (12 ga. stranded)

Simple (Undetected) DCC Wiring

Track Feeders, 20 ga. solid

3M Scotchlok 567

(All 12/20 ga.)

(Double 20 ga.)

• Wire color avoids NEC standards (12 and 14 gauge)

• 12 ga. stranded for “Track” (DCC Power) Bus (not “Block” Bus – more later)– DO NOT TWIST. Maintain ~1 inch separation

• 20 ga. solid for Track Feeder

• One pair of feeders for every section of track– DO NOT TRUST RAIL JOINERS (OR SWITCH POINTS) FOR ELECTRICAL CONTACT

– Nickel-silver rail is a poor conductor – compared to copper.

• All connections made with IDC’s (Insulation Displacement Connectors)– NO SOLDERING UNDER THE LAYOUT !!!!!

– Use appropriate IDC for wire sizes

AC-DC-DCC


Detector Characteristics:

• Types– Current Detector (requires conduction thru motor, light, resistor, etc)

– Position Detector (light beam, magnetic, contact, weight)

• Uses– Automatic Signal Systems

– Centralized Train Control (CTC)

– Grade Crossing Protection

– Automatic Turnout Actuation

Determine the occupancy of a block or specific location.

Current Detector

14 AWG

Block Wire

Cardstock

Placard

Team Digital

DBD2™

(DBD22™)

Power

ToSignal Logic(Computer)

From Track Bus To Block BusTo Block Bus

• Design Criteria– Sensitivity

» Detect decoder only» Adjustable

– False Positive Indication» 1 second turn-on delay

– False Dropout» 3 to 5 second dropout

– Isolated from DCC Track Bus– Distributed – not centralized

AC-DC-DCC


DCC Detector Wiring

• Detected rail (Rail A or Rail B) has its own “Block Bus” (14 ga. stranded)

• Gap only detected rail– Opposite rail becomes common rail

• All connections made with IDC’s (Insulation Displacement Connectors)– NO SOLDERING UNDER THE LAYOUT !!!!!

– Use appropriate IDC for wire sizes

• Detector must be on Block Feeder– NOT ON BLOCK BUS

DCC Rail A (12 ga. stranded)

DCC Rail B (12 ga. stranded)

Block 1 (14 ga. stranded) Block 2 (14 ga. stranded) Block 3 (14 ga. stranded)

Block 1 Current Detector Block 2 Current Detector Block 3 Current Detector

DCC Wiring With Current Detection

Block Feeders, 14 ga stranded

3M Scotchlok 567

(All 14/14 ga.

& 14/20 ga.)

3M Scotchlok 562

(All 12/12ga. & 12/14 ga.)

Block 1 Block 2 Block 3

AC-DC-DCC


DCC Switch (Turnout) Wiring

DCC Rail A

DCC Rail B

Block X

Block X Current Detector

Block Feeder

Tillig Turnout

• Power frog and switch points (or use DCC-Friendly Switches)

– DO NOT TRUST SWITCH POINTS FOR ELECTRICAL CONTACT

• Switch is part of Block X

Switch Point Power - Contacts on Tortoise)(Not needed with DCC-friendly Switches)

Tortoise

®

DCC Friendly

AC-DC-DCC


DCC Rail B

DCC

Ckt. Breaker

DCC Rail A

DCC Accessory Bus

DCC Layout Wiring – Multiple DCC Buses

Accessory

Decoder

DCC Rail B

DCC Rail A

DCC

Ckt. Breaker

17 ma.20 ma.

Tortoise 100 x .020 = 2.0 A

Signals 100 x .010 = 1.0 A

3.0 A

DCC

Booster

A Separate DCC Accessory Bus Provides:• Accessory Power independent of Track Power.• Sufficient accessory power for many devices.

XTortoise

®

Stalled

Motor

Locomotive and

Accessory Decoder

are dead!

Locomotive is dead.

Decoder is powered.

Accessories will draw ~5 times

more current than trains.

AC-DC-DCC


Camera

Monitor

LightingAccessory

Decoder

DCC Layout Wiring – Multiple Buses (Continued)

DCC Rail B

DCC

Booster

DCC Rail A

DCC Accessory Bus

Accessory

Decoder

Computer

Power Supply

+12 VDC

GND

DCC Rail B

DCC Rail A

DCC

Ckt. Breaker

Tortoise

®

AC-DC-DCC


DCC Layout Wiring – 12V DC Bus Applications

Camera & Monitor Lighting

AC-DC-DCC


Miscellaneous Stuff

PowerFast

Strap Gun

12-14NM

IDC Connector

Detector

AC-DC-DCC


Miscellaneous Stuff – Documentation !!!!!

AC-DC-DCC


Bus (Network) Architectures - General

Bus Network (RS485)

- Multiple devices (32 to 256)

- Expanded distances (~4000 ft)

- Must be linear (cannot be “treed”)

- Usually Master/Slave, Polled

- C/MRI®, NCE (&other) Command Buses

Point to Point (RS232)

- 2 devices (e.g., teletypes)

- Limited distance, ~10 ft. Hub

Star (Ethernet, USB)

- Fast (~100MB/S)

- Most popular local area type

- Requires Hub

Ring Network

- Continues to work

if ring is broken

- Usually large

numbers of users

Tree Network

(LocoNet®)

- Connections

and routing not

constrained

- Slower

transmission

speeds

- Peer-to-Peer,

Event-Driven

P P P

P P

P

P

S S M S

AC-DC-DCC


DCC Architectures (Digitrax vs. Others)

NMRA

RP9.2

No NMRA

Standard

Vendor

Dependent

CS

A

B

Cab Bus (RS485)

A L L

B

Control Bus (DCC Commands)

Track Bus (DCC Commands)

Optional

Most DCC Systems

TT

– Cab Bus is RS485 (IEEE Standard)

– Command Station is “Master”

– Master must “poll” each device to transfer data

– Cycle repeated continuously (constant activity on Cab Bus)

B

T

T CS/B

Command Bus* (LocoNet)

Digitrax DCC System

A A L L

Track Bus

Optional

T

*Combines Cab and Control Buses

– Peer-to-Peer relationship

– Distributed Intelligence – all devices equal

– Event Driven (only changes transmitted)

– LocoNet allows device-to-device communication

Note: This diagram does not address transponding.

B = BoosterCS= Command StationI/O= Input/Output DevicePC= Personal ComputerT = Throttle A = Accessory (Switch)L = Locomotive

May Be

Combined

Combined

AC-DC-DCC


Suppliers

• Logic/Electronics

–See Handout

• Signals/Electronics

–See Handout

• Signal Operating Software

–See Handout

Acknowledgements

• Digitrax and LocoNet are registered trademarks of

Digitrax Corporation

• NCE is a registered trademark of North Coast

Engineering Corporation

AC-DC-DCC


The Deepwater District Construction Crew

It’s not the destination that’s important,

it’s the journey (with friends).

AC-DC-DCC


STOP!(Then Proceed)

Thank you for your interest and attention!

Standby For:

Signals

By

Spreadsheet

AC-DC-DCC


signal systems in model railroading handouts/c467_albers ac... · placard team digital dbd2™...

Documents