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| Product: | SE8C Signal Decoder by Digitrax
| | Price: | msrp $125.00 USD
| | Reviewer: | Elmer McKay
| | Notes: | Controls 32 signal heads, 8 slow motion switch machines (such as the Tortoise), and has inputs for 8 sensors. |
Elmer Mckay presents to us a review of the SE8C Signal Decoder from Digitrax. The SE8C will be showing up in many of our project layouts and this is a great run through about what the equipment is about. We hope you enjoy this new series of DCC focused articles. We welcome Elmer and all his knowledge of DCC to the site. There is nothing like a working signal system on a model railroad layout that attracts more attention except the possibility of sound. With today's DCC technology, good looking signals that are completely operational and automated is a real attention getter. Prototypical signal Interlockings and CTC systems can now be modeled just as effectively as we model our scenery and buildings. Just picture the scenes below with a train passing the signals and the signals changing to red to reflect the block the train is entering being now occupied.
When installing a signal system on a model railroad layout, there are two ways that it can usually be done. One is by using stand-alone electronics, switches and sensors. One circuit board is used for two or three blocks and the external sensors and switches are connected to it. Signals and a power supply are also connected to the circuit board and you have a simple signal system for a few blocks.
The second way to implement a signal system is to use inputs and outputs to a computer. Some form of sensors or train detection is still required, as well as the signals and a power supply. This has a very big advantage over the simple signal system, previously described, in that the signals can be just block occupancy type signals (also know as ABS) and/or they can also be used for modeling Centralized Traffic Control (CTC) signals.
The SE8C Signal Board by Digitrax will do either ABS signals, CTC signals, or both of them together.
The SE8C Signal Decoder is one of Digitrax latest products and is actually one part of a complete Modular style signal system. It is the main interface between the computer and the layout's signals. The other parts in the Modular System consist of Signal Mounting Kits, (two different types) and the Cables & Connectors required to connect the signals to the SE8C Board. Since the system is in modular form, it is as close to being a "Plug-and-Play" system as you can get for a model railroad signal system.
The Board is state of the art in both design and manufacturer for the consumer electronics market. The board is very clean looking and uses SMT (surface mount technology) parts where practical.
There are three types of interface connectors that are used on the Board. First is a standard 44 pin Edge Card connector which is used for power and auxiliary devices and is part of the boards mounting system. Next is the standard LocoNet jacks that will accept the RJ12 connectors on the ends of LocoNet cables. Third is eight, ten-pin IDC connectors that the signal cables plug into.
There are also two push-buttons with their associated LED's. One is for entering the Board ID mode, and the second is for entering the Option Selection mode. ID and Option settings can be changed or selected by using a Digitrax throttle or through a computer link via the LocoNet.
The Board is capable of operating 32 signal heads, 8 Tortoise switch machines or low current stall type motors, and sensing 8 inputs, all at the same time.
 Digitrax has laid out the signal connections in a Security Element or "Plant" type configuration that controls the 4 signal heads that usually surround a turnout. Each "plant" is implemented on one signal cable. Thus, each signal cable controls 4 signal heads, and since there are 8 IDC connections on the SE8C board, you have 32 controllable signal heads. The signal heads can be set up in almost any fashion or configuration that you want, from two signals with two heads each, to four signals with one head each. This makes for a very versatile system.
Control of the signals can be by a Digitrax hand held throttle, or by computer. A Digitrax LocoNet is required for signal operation. (By setting up a LocoNet on a non-Digitrax DCC system, and with the software programs now available, the SE8C is not limited to just Digitrax layouts, but can be set up for use on most DCC systems that have a connection for a computer.)
The SE8C Board allows for using different types of LED signals by changing the Option Switch setting and the way the signals are wired to the Signal Mounting kit (which is actually a small printed circuit board that plugs into the signal cable). The signal types used can be the standard 3 light signal in all of it's variations (including Position Light and Color Position Light types), 2 light signals, and searchlight signals using two or three lead bi-polar LED's. Current limiting resistors for the LED's are built into the Signal Mounting kit board circuitry. The Board also allows for use of semaphore type signals. The semaphore blades are driven by slow motion type stall motors such as the Tortoise switch machine, connected to the switch machine outputs. The different signal types are selectable by using the option mode.
 A B&O CPL type signal showing the Digitrax signal interface board and connector known as an SMBK or Signal Mast Base Kit. The wood plug is the way that I chose to mount the signal on the layout. This makes the signal removable.
Each of the signals are capable of showing four aspects. The three standard colors of Red, Yellow, and Green, plus a fourth aspect. The fourth aspect can be selected from either of the following: Flashing Yellow (the default); Flashing Green; Flashing Red; or Dark.
The SE8C is also capable of being connected to various wiring styles of model signals. Common Anode (the default) or common Cathode. The SE8C as supplied by Digitrax comes with the 44 pin edge connector (blue) and a Test Mast (SMBK) with cable. (Photo by Digitrax)
As with most Digitrax devices, the board address can be changed so no two boards will interfere with each other. On the SE8C, there are actually four sets of addresses. One is the Board ID Number. The other three are Device Addresses. If you are an experienced Digitrax user, you will recognize this. If you are a new user, it can be a little confusing at first. Allow me to go into just a little more detail on this. The three Devices that have Addresses on the SE8C board are:1- the Signal outputs; 2- the Motor or switch machine outputs; and 3- the Sensor inputs. Each type of Device has a range of addresses. The Board's default ID number is 1. For the board ID number of 1, the Motor or switch machine output address are 1 thru 8. The Sensor input addresses are 1 thru 8. (An output address is different than an input address.) And the Signal addresses are 257 thru 320. If you change the Board ID number, all of the address ranges will change. If you are using other Digitrax boards for turnout control and/or block detection, you must know what those Device Addresses are, and the address of the SE8C Devices. None of the Device Addresses should be the same. OK, now for a simple example. If you have a DS64 with a board ID of 2, and you have not changed the individual Turnout Addresses (on the DS64) the default Turnout Addresses will be 5 thru 8. When you connect your SE8C Board, and it still has it's factory ID of 1, the Turnout Addresses are 1 thru 8. So you can see that Turnout Addresses 5 thru 8 will be in conflict between the DS64 and the SE8C.
The manual is very well written and explains all aspects of installing, wiring, and using the SE8C Board with a Digitrax throttle. The addresses used to change the signal aspects of the different signal heads are in a chart and easy to understand. You can download the manual from this link: http://www.digitrax.com/ftp/se8c.pdf There are numerous diagrams and photographs that will help the user through the entire process. There is even a section that covers installing the signals on your layout using the Digitrax signal interface boards and other mounting parts. There is also additional information and instruction files posted on the Digitrax web site that covers different types of signal wiring such as the B&O and PRR color and light position signals, semaphore signals, and two aspect mode signals. Links are provided to computer software programs that can be used to control the signals on the SE8C. The software that I used for setup, testing, and installation on our club's HO layout is JMRI Panel Pro.
The Board itself is easy to mount and install. As was mentioned before, connecting the signals is easy and straight forward. The cables (not supplied with the SE8C, but available from Digitrax as well as other sources) are color coded to insure that they are mounted or connected properly. The connections are not fool proof and can be reversed, but because of the thought out design, it will not damage or hurt either the Board or the signals in any way if you would reverse them. The only thing to be affected by reversing them is the signal device address for one particular head will be assigned to another signal head in the same plant or security element.
Some soldering skills are necessary to make the connections to the 44 pin edge connector. The pins are close together and care is necessary so the adjacent pins are not shorted together. Although not covered in the manual, I found that wiring for installation works better if the wires are soldered to the pins of the edge connector before installation, and then routed and connected to a terminal strip. Once the connector and board is mounted, it is not very easy to solder wires to the bottom row of pins. By using the terminal strip, connecting layout wiring to the terminal strip is easy.
Although the SE8C will control the signals on the layout with a throttle, the common way to do it is by using a computer and control program, as was mentioned before. However, to make the signals work automatically, other inputs to the computer are required. You need to know where the trains are, and that takes block detection. If you want to know which way the turnouts are positioned, that also takes at least one input per turnout. The Digitrax BDL-168 will provide block detection, and the Digitrax DS-64 will provide turnout feedback to the computer as well as allowing you to control the direction of the turnouts by computer, throttle, or control panel.
One way to mount the SE8C and BDL-168 is to attach them on a wood board. By pre-wiring the 44 pin edge connectors (blue connectors) and connecting those wires to terminal strips, connections to the layout is straight forward. (The numbers 6 and 14 are the board addresses.)
Another factor to consider when mounting the SE8C Signal Board is what is going to be used for block detection. In my signaling scheme, I decided to use the Digitrax BDL-168 for block detection. I then designed the mounting area to hold both the BDL-168 and the SE8C boards and their respective terminal strips.
Once the Board is set up, signals connected, block detection in place, and the computer and control program set up, the signal system using the SE8C works flawlessly. The signals change aspect from green to red to yellow as a train passes and continues it's journey. This adds a realism to a model railroad that is hard to match.
With the addition of the SE8C Signal Board to the growing line of Digitrax products, it is now easy to set up a complete and operable CTC control & signal system and computer control panel for your Model Railroad, and do it at a reasonable cost.
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