Depending on who you listen to, mainline turnouts may need to be isolated from their surrounding blocks. Leaving out mainline turnouts, I estimate that I will have around 42 blocks. This assumes a few things:
- Trains will be no more than 10' long. Longer than this will cause the train to go through multiple scenes at the same time.
- Block will be roughly 12-15' long, but shorter blocks are better
- Lower level will be mostly double-track main
- Helix will be double-track
- Upper level will be mostly single-track main with passing sidings
- Mainline passing sidings will be detected
- Industrial areas and sidings will not be detected
- Staging yards will not be detected
Any track that is not detected will be isolated but then connected to a common track bus.
Assumptions
A few assumptions go into this discussion. I'm using a 14 gauge bus wire and 20 gauge feeder wires, using Scotchlok 905 suitcase connectors. The layout will be broken into 4 or 5 power districts to help control short circuits. I will also be controlling/monitoring the layout by way of JMRI through a LocoBuffer-USB connected to the LocoNet network.
Product prices are based on ModelTrainStuff.com and TrainWorld.com published prices.
Digitrax Block Detection
Note: The full list of Digitrax detection/signaling products is available here.
The BDL168 occupancy detector ($119) is the primary product for block detection. It requires a separate power adapter (PS14 - $9.97) This unit will manage 16 detection sections using the schematic below, located in the BDL168 instruction guide.
Since a detection section will likely be 12-15' of track, the feeders from each piece of track need to be combined and then, using heavy gauge wire, run all the way back to the input port on the BDL168. The heavy gauge wire is required for the detection to work using the Digitrax product. This translates into a lot of wire going between blocks and the BDL168s.
Digitrax does offer a supplemental product called the RD2, which is a remote sensing diode. Using this product (which can detect two blocks), you can then use small gauge wire (think network cable) to transmit the detection information back to the BDL168. See the diagram below from the instruction sheet.
Digitrax does offer a supplemental product called the RD2, which is a remote sensing diode. Using this product (which can detect two blocks), you can then use small gauge wire (think network cable) to transmit the detection information back to the BDL168. See the diagram below from the instruction sheet.
Since a single CAT5 network cable actually has 4 pairs of wires, you can consolidate this detection wiring down nicely. However, this requires buying an RD2 for every two blocks. Each RD2 is listed at $7.65 at Tony's Train Xchange. The RD2 is powered through the track bus and does not require a separate power supply.
Digitrax is well supported and is one of the major systems used for DCC control. The documentation is clear and they do offer e-mail and web-based support. Their warranty support is also outstanding.
Pricing this out, you have these items to purchase for 16 detection blocks:
- BDL168 - 119.00
- PS14 - 9.97
- RD2 x 8 - 61.20
Total: 190.17, or 11.88 per block
RR-CirKits Block Detection
RR-CirKits is probably best known for the LocoBuffer product, as well as the new Layout Command Control (LCC) systems. The product prices are based on the RR-CirKits "4+" prices. They give this discount for NMRA members, as well as bulk discounts.
The controller product is the TC Mark II product ($114.22), which supports 64 input/output lines. For block detection, you add a BOD-8 ($35.40) and a CT-Coil-Set-8 ($13.60) for each 8 detection sections you want to manage. The detection wire passes through the center of the coil. The coil is then connected using twisted pair wire back to the BOD-8 board. The detection coils can be placed near the actual track being detected, minimizing the amount of wire required. In addition, no special wire design is required. As long as the detection wires pass through the coil, they can then connect directly to the track bus wire. The diagram below includes a lot of extraneous items, but the basic block detection is easy to see on here.
The TC Mark II connects to the LocoNet, but requires a separate power plug.
While some of the documentation is a bit hard to understand, one bonus is that the owner of the company was more than happy to answer my beginner questions and provide some recommendations.
Pricing this out, you have these items to purchase for 16 detection blocks:
- TC Mark II - 114.22
- BOD-8 - 35.40
- CT-Coil-Set-8 - 13.60
- PS-S-12-800 power supply - 9.30
Total: 7.90 per block, based on the TC Mark II + power supply supporting 64 blocks
Team Digital Block Detection
The BlocD8 product provides block detection using a system similar to both of the other systems. The DBD22 product can detect two blocks of track and the BlocD8 can detect eight blocks of track. However, the DBD22 product does not work on its own, while the BlocD8 includes LocoNet connections. It is powered via the track bus. Similar to RR-CirKits, the detection section wires go through the center of the coil.
Tony's DCC Exchange has the BlocD8 product available for 84.95, which translates to 10.61 per block.
Summary
Based on this research, the RR-CirKits product appears to be the best price-per-block for detection capabilities. A single TC Mark II will be able to provide all the detection needs for the entire layout as well as provide signaling capability down the road.
Did you also consider Olin's Depot OC1 Quad DCC Block Occupancy Detector Unit(http://www.olinsdepot.com/odepot/products/oc1/index.htm)?
ReplyDeleteI had never heard of their product, nor seen it used on any of the layouts I've visited. It does not seem to have any sort of interface to a Digitrax/LocoNet network, it just has LED block indicators.
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