I have a bunch of experience with BDL168's, but not with transponding.One thing I can tell you is be careful to keep the entire length of all conductors attached to each block under 50 feet in length. This includes the length of the wire run to the track and the track itself.At my club, we still have 5 BDL168's installed, and in certain areas we have constantly lit detection sections. Why? Because with 16 blocks, we ran some 14AWG feeders 60 feet from the BDL to the track. Yes, they don't tell you this, but if you attach enough wire to the BDL, it will actually set off the detection section.So if nothing else, try to keep your wire runs as short as possible.FWIW, my club has switched to the Tower Controller type of block detection that runs a wire through a toroid. This detects amperage, not resistance, so it doesn't matter how long the conductor is.
Look at it this way.
A BDL168 has 8 Transponding zones, 4 Power Zones and 16 Detection Sections.
Blocs are comprised of a single Detection Section or Multiple Detection Sections. Usually you would have a Run section, Approach section, Stop Section within a Block to have an engine stop at a specific spot, consistantly, on your layout, in a realistic manner.
Zones are just power related.
Transponding Zones are a totally different beast but can be used as 8 Detection Sections as well giving you a total of 24 Detection Sections
Depending on what you are trying to implement determines how you will "block" your layout.
That is how I viewed it.
Marc
The BDL-168 detects 16 blocks. The circuitry used makes it nicely divide into 4 sections - each section has its own power feed, so each section can come from a different output on a circuit breaker, or a different booster. That's all.
I see no point in making multiple tiny blocks. It just means a train will report as occupying multiple blocks all the time, compared to longer blocks where the train would show in Block A, then A and B as it crossed the gapse into block B, then just B, etc.
The only place for short blocks is if you want to detect OS sections, effectively the turnout
Say you had something liek this, a passing track:
----<=======>----
You could do that as 4 blocks, the entrance, the upper track, the lower track, and the exit. But to enable interlocking, you might want to detect the turnouts independently, that would need 6 blocks. entrance, left turnout, upper track, lower track, right turnout, and exit.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Another beginner question:
I am going to hook up the BDL 168 for my occupancy detection. I will be using it with iTrain software. I have a question about terminology.
The BDL168 has 4 "Zones" each zone has 4 sections or sub-zones. Is one ZONE a block and each sub-zone is a part of a block, or is a section called a block making the BDL able to detect up to 16 blocks?
I read that it is recommended to split a block into sub-sections to increase the accuracy on where exactly the train is located within a block. Is this what the Zones vs. sections is about?