Progress - Updated February 20, 2016
This past month I have been installing NCE BD-20 block detection
circuits on each of the blocks. So far I have 11 of the 18 blocks
completed. Each BD-20 output is run to an NCE AIU which
interfaces to the Cab bus. Each block is assigned an AIU address
which is used in the JMRI software to indicate that a block is
occupied. Once complete, there will be 20 blocks wired to 3 AIUs.
Below are photos of some of the components used to compete this
This is the table I made up to keep track of what address of each AIU
was assigned to each block. The addresses are designated when
building the detection blocks in JMRI. The items in bolder black
are switch indicators that may be assigned in the future.
This photo shows the two BD-20 detectors in the center, and to the
right is the AIU. To the left is a terminal strip with the DCC
track feeders. The positive side was run through the current
sensor on the BD-20 and then continued to the track. 5 volts also
must be run to the BD-20 and I use an old computer power supply to
generate the voltage.
In areas where I didn't have 5 volts available nearby, I built a
circuit to generate the 5 volts from the DCC track bus. This
is the beige card in the middle of the photo. Here you can see
track 2 of the Youghiogheny block is occupied indicated by the lit LED
on the BD-20.
Resistor wheel sets were made using surface mount 4.7 Kohm resistors.
The resistor was electrically connected to the wheels using a
conductive ink pen. I am having issues with the wheel sets
consistently tripping the BD-20 detectors. I am thinking it is
either dirty wheels or track. Currenly I only have two sets
installed on all my cabooses. Maybe once I have more rolling
stock also converted, the detection may be more reliable.
This is a screenshot from the JMRI Control Panel Editor. Here you
can see each of the blocks (switches are not controlled). The
only blocks remaining for wiring are Confluence, Meyersdale, and Sand
Patch. i have an order from Tony's Train Exchange for the
Close-up of the Rockwood block showing track 2 occupied.