Page updated on Thursday, February 5, 2026
Latest work completed:
Ran 5 VDC and 12 VDC power busses around the layout.
Got the inline connectors for the Cab Bus. They are used on the removable
duck-under bridge.
All of the BD20s were wired.
10 of the 31 BD20s were showing a false trigger that the tracks were occupied.
Long blocks can have a capacitance that draw enough current that can trigger a BD20.
All three Schenley tracks falsely triggered.
The Cumberland block was cut into two blocks of 13.5 ft. That fixed the issue there, so I have
to purchase two more BD20s for the new block called "Cumberland Terminal".
I also tried reducing the number of times the wire passed through the current sensor to one.
That fixed a few blocks, but some of them failed when testing each block with a
4.7K ohm resistor (simulating one rail car occupying a block).
The resistor didn't create enough current to be detected.
The BD20 documentation recommends adding a potentiometer to the card to adjust the threshold level.
That fixed the false trigger issue, but it increased the trigger threshold above the current of the
4.7K ohm resistor across the rails .
I then did some research on the NCE Group page on Groups io, and found that there is a way to cancel out the
block capacitance.
Description of the solution
So I tried it on one of the BD20s using a 500pf capacitor and alligator test leads and it worked.
It makes sense because the capacitance circuit is simulating the current
from the block capacitance, and because you run it through the current sensor
in the opposite direction, it essentially cancels out the block capacitance current.
I then had to figure out a reliable way to incorporate the capacitor into the track detection circuit.
The capacitors I had have very thin leads, so soldering wires directly to them wouldn't be very sturdy.
I had some old circuit cards for integrated circuit chips and cut them in half to mount the capacitors.
Circuit cards with mounted capacitors and the wire leads.
I then incorporated the card into the track detection current sentors to make sure there were
no false triggers, and that worked. Then I tested the blocks with a 4.7K ohm resistor
and it was properly detected.
Card installed and no false triggering on the BD20s.
Next work to do:
Make more cards with capacitors to fix the remaining BD20s that are false triggering.
Place an order for 2 more BD20s, another AIU, and two additional UTPs.
Overview of the Layout
Golden spike is in place (11/23/2025). This spike was the golden spike from my last layout in Maryland.
Wiring for the command station and power boosters. I use the computer power supply for any circuits and
LED lighting (5 VDC) and 12 VDC for incadescent bulbs around the layout.
Duck-under (removable) bridge painted and wired.
Wiring for power to the tracks and detection current sensors for Laughlin Jct, Demmler, and the URR track.
Used WAGO connectors for the 12 AWG power bus wiring.
Also used them when more than two wires were connected to a terminal screw.
Worked much better than the wire nuts that were used on the previous layout.
First train run to check Track 1. Train ran smoothly with no issues.
Took 7 minutes to run over the entire mainline (approx 3 miles) at a scale 25 mph.
Pitt block occupany detector wired and verified that it worked when a train entered the block.
Diagrams of the wiring
Layout Specifications:
Mainline Length:
Track 1: 177.5 ft (2.93 scale miles)
Track 2: 181.5 ft (2.99 scale miles)
Minimum Walkway Width: 35"
Minimum Subroadbed Height: 44.5"
Maximum Subroadbed Height: 48.75"
Minimum Radius: 30"
Curve Easements: 18" transition, 0.5" offset
Super Elevation: 0.030"
Atlas Code 100 Flex Track and Switches
Tangent Track Center to Center: 2"
Curved Track Center to Center 2.25"
Yard Track Center to Center: 2"
Mainline Maximum Grade: 1.5%
Mainline Crossovers: #8
Spurs off of the Mainline: #6
Yard/Industrial Switches: #4
DCC: NCE Powerhouse Pro System with 3 power districts
JMRI Software
Track charts showing the location of switches, tunnels, bridges, elevation, grade, and the interlockings and blocks.
Some of the track is not totally accurate due to space, but all the tunnels and bridges are properly located.
Train room dimensions along with the approximate dimensions of the layout.
The size changed a bit as I was laying out the track. The room is approximately 755 sqft.
A photo from my old layout in Maryland (2001 - 2019).
P&LE 1589, an MP-15 leads a load of coated pipe past the Westinghouse factory.
I am a member of the following railroad historical societies.
