DCC on the Pacific Southern

Brief History

• House built in 1953 by Bob Latham• O-scale layout initially• Changed to HO around 1960• Club started in 1964• Layout rebuilt and expanded • House bought by Geoff Green in 1991• Addition to house, layout expanded again• Conversion to DCC

Choosing a system

• Preferred features– Multiple boosters– Command station separate from booster– Computer connection to command station– Separate cab and power buses– Optical coupling for power bus– Separate cabs– Wireless capability– Circuit breakers and reversers

DCC Equipment

• 1 NCE 10 amp booster• 3 CVP 10 amp boosters• NCE command station • NCE wireless receiver and 2 repeaters• NCE cabs• NCE Powercab• 36 circuit breakers• 6 reversers• Over 200 detection circuits

DCC Power Distribution

NCE Booster Panel

CVP Booster Panel

Foss Distribution Panel

Connections at Foss

Detection Circuit

• Based on design in NMRA Bulletin• Diode bridge in lead to track• Optical coupler• Capacitor timing circuit• Schmitt trigger• Dual open-collector outputs, one for indicators on

panels, the other for computer input• 4 circuits per board or 6 circuits per board• 5000 ohm resistor per car

Detection circuit schematic

Boards and Microcomputers

• Circuit boards designed on PC using free software from Express PCB

• Uploaded for fabrication• Microchip computers used– 16F84– 16F873– 16F874

• Simple chip programmer plugs into USB socket on PC

Circuit board for 4 detectors

Circuit board for DCC Reverser

Throttles and Cabs• 1 NCE Procab converted for wireless• 5 NCE Power Pros (potentiometer) converted for wireless• 1 NCE Power Pro (encoder) not converted • 1 NCE Power Cab in workshop for testing and

programming locos; connected to shop PC to use JMRI software

• Old Aristo Craft wireless throttles used with analog-to-digital converters connected to dispatcher ‘s computer

• Many members bring their own cabs

Command Station, Cab Bus and Power Bus

• Command station located in dispatcher’s booth and connected to dispatcher’s computer

• 6-conductor cab bus connects command station to many UTP Fascia Panels and to ceiling-mounted wireless transmitter

• 2 wireless repeaters• 2-conductor power bus connects command station

to boosters• Program track outputs on command station not

used

Locomotives

• Variety of decoders and sound decoders used• Card file to keep track of loco and cab

numbers• Programming done in shop using Power Cab

and/or JMRI• All locos in consist use same (lowest) number• Some members very skilled at installing

decoders and sound systems

Problem areas• Reversing sections

– Multiple tracks at “YARD” and “CLIFF”– Approach tracks not long enough– Sequential sections at “PORT”

• Detection Circuits– Locos draw low current when not running

• Staging tracks– Laid-up trains should be turned off

• Direction– Cannot determine direction of train electrically

• Wireless cabs time out• Interference with signal system• Strange things sometimes happen

Revisions to Towers

• Toggles for controlling remote cabs removed• Buttons for selecting cabs removed• Switch controls remain• Some block toggles kept to turn off trains

and/or select direction in reversing sections• Detection lights remain• Telephone system simplified

DELL Tower