DCC on the Pacific Southern

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
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
• 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
• Old Aristo Craft wireless throttles used with analog-todigital converters connected to dispatcher ‘s computer
• Many members bring their own cabs
Command Station, Cab Bus and Power
• 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 ceilingmounted wireless transmitter
• 2 wireless repeaters
• 2-conductor power bus connects command
station to boosters
• Program track outputs on command station not
• Variety of decoders and sound decoders used
• Card file to keep track of loco and cab
• 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

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