BMD16NSD version 1.2 Feedback decoder with 16 contacts with integrated current detection for the S88bus Compatible with a.o. Märklin Digital, Uhlenbrock Intellibox, Fleischmann TwinCenter and LDT HSI88 Compatible with the s88n standard Suited for all 2rail digital model railroads
The BMD16NSD All computer controlled model railroads need a good system providing feedback from the track. The BMD16NSD was especially designed to provide this feedback reliably and affordably for 2rail model railroads. The BMD16NSD is fully compatible with the widespread S88 bus and the new s88n standard. 16 contacts The BMD16NSD has 16 contacts with separate inputs and outputs. That is twice as much as most feedback decoders on the market today. Each contact can be assigned to a different power source, giving you optimal flexibility when planning and building your layout. In groups, independent or both The 16 contacts are by default combined into two groups of 8. You only need to supply power to two inputs to use all 16 outputs. But you have the option to power each contact via its own input as well. This will give you the choice between two groups of 8, 16 independent contacts or any combination of the above. This a major advantage when you want to connect a reversing loop module or power different sections by different boosters. The BMD16NSD will give you all the flexibility you will need. Screw terminals or inexpensive connector strips The BMD16NSD can be equipped with either practical screw terminals or inexpensive connector strips. The screw terminals are intended for the default configuration with two groups of 8 contacts. The connector strips can be used with any configuration. Attractive kit The BMD16NSD is an easy to assemble alternative to similar decoders and kits on the market. The BMD16NSD is a lot cheaper than feedback decoders from model railroad manufacturers. Manual BMD16NSD version 1.2 page 2
Universal standard with reliable cables The BMD16NSD can be connected to your system via normal S88 cables or via UTP network cables. Network cables are cheaper and provide better protection from electrical interference. The cables can be much longer than normal S88 cables. The BMD16NSD is fully compatible with the s88n standard, It can be connected directly to any equipment bearing the s88n logo. Less chance of feedback errors The BMD16NSD features an improved circuit. Together with the use of network cables this greatly reduces the chance of false feedbacks from your layout. Connect other decoders sideways If mount several BMD16Ns and/or BMD16NSDs right next to each other, you will need only a simple print connector or just a few wires to connect the decoders. You do not need any cables between the decoders. This will save you wiring, space and money. Attention: The connectors on the BMD16NSD are not normal network plugs. Never connect the decoder to a PC or any other network device! Manual BMD16NSD version 1.2 page 3
Train detection and the BMD16NSD Train detection based on current detection is the best choice if you want reliable feedback from your layout. You can create train detectors by dividing the track into isolated sections. Each section is connected to a different contact of the BMD16NSD. When a train is in a section, the decoder will register the section as occupied. When each locomotive and each car is detected, it is always clear which tracks are free and which are not. Even lost cars can be detected. This greatly reduces the risk of collisions. Current detection The BMD16NSD reacts to anything on the track that picks up a current. That can be a locomotive or a car with interior lights. Even a very small current running through the track will generate a difference in voltage inside the decoder. The difference is registered and the train is detected. The BMD16NSD can also detect cars without lighting if you put a drop of resistance lacquer on the isolation in the axle (e.g. Trix lacquer 66882). Soldering You do not need to be an electronics expert to build a BMD16NSD, but some experience in soldering is advisable. Always use a small soldering iron with a tiny tip and thin solder with a raisin core. Never use flux or another soldering aid. First heat up the joint you want to make with the soldering iron and then apply the solder. You have made a good joint if the solder forms a small pyramid. Wait for the solder to cool down and then cut the wires with a pair of pliers. Suggestions Resistor are cheaper when you buy them in a package of a 100 pieces. The resistors of 47 Ω and 100 kilo Ω are listed as a package of 100 pieces. If you are assembling more than one decoder, be sure not to order too many resistors by mistake. Another option to save money is to leave out the IC sockets and to solder the ICs directly onto the board. If you choose to connect the track via connector strips, you might want to consider using a female counterpart as well. You can solder the wires to the female connector on your workbench and just snap the female connector on the decoder. Please note: The circuit board might have been updated since the pictures of this manual were taken. Please place your components according to the markings on your board wherever they differ from the ones in the pictures. Manual BMD16NSD version 1.2 page 4
The parts You can order the components from Conrad (www.conrad.com) or Reichelt (www.reichelt.de). The catalogue numbers are included in the list below. Of course, you can also go to your local electronics shop. All components are mainstream and should be readily available. Count Description Conrad nr. 16 resistor 47 Ω 403881 (100 pieces) 1 resistor 330 Ω 403199 17 resistor 10 kilo Ω 404160 (100 pieces) 2 resistor 100 kilo Ω 403490 1 resistor 220 kilo Ω 403539 16 rectifier B80C1500 501441 1 LED 3mm green 184713 1 capacitor 100 nf 453358 1 transistor BC517 154695 10 16 pin IC socket 1 189529 4 ILQ620/PC844 optocoupler 153612 4 IC 4044 172871 2 IC 4014 172707 6 3pole screw connector 2 731891 2 connector strip 3 736942 2 RJ45 western connector 716148 1 Only needed if you want to mount the ICs in sockets. 2 You can only choose screw connectors if you plan to use the contacts in two groups of 8. 3 You only need one if you are fitting the board with screw connectors. Manual BMD16NSD version 1.2 page 5
Assembly The circuit board has a white print on the component side. The print will tell you exactly where each component has to go. The lowest parts are put in first, the highest parts last. This order makes it easy to flip the board over and solder the parts without the need of holding them into place. 1. Choose your configuration Before you do any soldering you should decide how you want to configure your BMD16NSD. Your choice will determine which connectors you can use and if you have to cut any tracks on the soldering side. Two groups of 8 contacts (default configuration) You can use screw terminals or connector strips and you do not have to change anything to the board. When you are ready to connect the decoder you will only need one source of track power for each group. The power is connected to the outermost terminals (group 1 and group 2). Some contacts independent You can only use a connector strip. On the soldering side you have to cut the connection between the rectangular islands for those contacts that have to be independent from the rest. You can always reverse the cut by connecting the islands with a drop of solder. The inputs of the independent contacts are connected separately. You only need to connect one input per group of the contacts that still make up a group. 16 completely independent contacts You can only use a connector strip. On the soldering side you have to cut all the connections between the rectangular islands. Again, this can be undone by connecting the islands with a drop of solder. The inputs of all contacts are connected separately. Manual BMD16NSD version 1.2 page 6
2. Resistors The decoder has several resistors from different values. Resistors are indicated by a small rectangle with a number in it. For example, a rectangle with 330 indicates a 330 Ohm resistor. The colour code on the resistors denotes the value. The direction of assembly is not important as long as the legs are in the right holes. Used values: 47 47 Ω yellowpurpleblack 330 330 Ω orangeorangebrown 10k 10 kilo Ω brownblackorange 100k 100 kilo Ω brownblackyellow 220k 220 kilo Ω redredyellow 3. Rectifiers The board has 16 rectifiers: the black circles with four legs. The rectifiers have to be mounted in a specific direction. The + on the rectifier has to be in the same spot as the + on the board. You might consider mounting the rectifiers about 1 cm over the board; they are easier to replace in case of a defect. Manual BMD16NSD version 1.2 page 7
4. IC Sockets The IC sockets have a notch on one side. The notch indicates where pin 1 of the IC goes later. When mounting the IC sockets the notch of the socket should be on the same side as the notch in the white print. 5. LED The LED comes in the middle of the board. The longer leg should be in the hole marked with +.. Manual BMD16NSD version 1.2 page 8
6. Capacitors The decoder has 1 capacitor of 100 nf (marked 104). The capacitors is indicated by a rectangle with 100n next to it. The direction of assembly is not important. 7. Transistor A semicircle with BC517 marks the place of the transistor. The flat side of the transistor should point to the bottom of the board. 8. Connectors for the tracks If you opted for screw terminals, the connectors are clicked together and mounted in a single row. The pins cover the 16 outputs and the two common group terminals (group 1 and group 2). Have you chosen connector strips? Cut the long strip to 32 pins. The strip covers all 16 outputs and 16 inputs. The common group terminals are left open. Manual BMD16NSD version 1.2 page 9
9. S88bus connectors Cut two pieces with six contacts from the long strip connector if needed. The location of the two strips is clearly marked on the board. You can leave out these connectors if you only plan to use network cables. 10. RJ45 connectors The connectors should firmly click into the holes. You can leave out the connectors if you plan on only using the standard S88 cables. 11. IC s You can now press the ICs very gently into the sockets. The text below the socket tells you which IC goes where. The right direction is critical. A notch or dot indicates pin 1 of the IC. This side should correspond with the notch of the IC socket. Please note that all ICs are pointing to the right! Manual BMD16NSD version 1.2 page 10
Final check Congratulations, your board is now ready. Please review your assembly carefully. Are all components in the right place? Are the rectifiers, the ICs and the transistor mounted in the right direction? Are all joints soldered correctly and are there no shortcircuits? If everything checks out fine, you can connect the BMD16NSD to your system. Manual BMD16NSD version 1.2 page 11
Connecting your BMD16NSD Connecting to a central unit The first BMD16NSD is connected to the S88 bus on your central unit. The cable is connected to the decoder on the side labelled richting centrale. When your decoder is connected correctly, the green LED will come on. It is recommended to use the s88n adapter (sold separately). This small adapter changes the standard S88 connection on your central unit into a s88n connection. Instead of a normal S88 cable, you can now use a reliable and inexpensive network cable to connect your first decoder. More decoders Successive decoders are connected in a chain by preferably a normal network cable (NOT a cross cable). Or else using a standard S88 cable. You can use the s88n adapter to make decoders with only a standard S88 connection s88n compatible. This allows you to wire your entire chain of feedback decoders with network cables. The arrows on the decoder indicate the direction of the flow. The order of the decoders determines how the contacts are numbered. The first decoder has contacts 1 to 16, the second one 17 to 32, and so on. The BMD16NSD can be combined with other brands of decoders in any order. With most central units you can connect up to 31 decoders with 16 contacts to the S88 bus. Manual BMD16NSD version 1.2 page 12
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module PWR BMD16NSD www.floodland.nl/aim naar centrale 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module PWR BMD16NSD www.floodland.nl/aim PWR BMD16NSD www.floodland.nl/aim naar centrale naar centrale ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module PWR BMD16NSD www.floodland.nl/aim naar centrale 33 t/m 48 17 t/m 32 1 t/m 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Groep 1 Groep 2 Groep 1 Groep 2 Groep 1 Groep 2 (c) 2008 Huib Maaskant Eddy de Boer (c) 2008 Huib Maaskant Eddy de Boer (c) 2008 Huib Maaskant Eddy de Boer Connecting the track The BMD16SD is inserted in the red wire running from the central unit or booster to the track. Typically this wire feeds the right rail (viewed in the direction of travel). The right rail is divided into section with plastic rail joiners. Each section is connected to different contact of the decoder. Sections without detection should be powered via four diodes. This ensures correct detection at the edge of the detection sections. intellibox Detection section 1 Detection section 2 Groep 2 Groep 1 1N4001 1N4001 (c) 2008 Huib Maaskant Eddy de Boer 1N4001 1N4001 intellibox Two groups of 8 contacts with screw terminals You connect both common group contacts (groep 1 and groep 2) to the red wire from the central unit or booster. Each group can be fed from another source, e.g. group 1 from the central unit and group 2 from a booster. Manual BMD16NSD version 1.2 page 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module PWR BMD16NSD www.floodland.nl/aim 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module PWR BMD16NSD www.floodland.nl/aim naar centrale naar centrale Group 1 consists of contacts 1 to 8, group 2 of contacts 9 to 16. Next, you connect the outputs of the 16 contacts to the various detection sections. Detection section 1 Detection section 2 Groep 2 Groep 1 1N4001 1N4001 (c) 2008 Huib Maaskant Eddy de Boer 1N4001 1N4001 intellibox Two groups of 8 contacts with connector strips You connect one input within each group to the red wire from the central unit or booster. Each group can be fed from another source. The common group contacts are not used. Next, you connect the outputs of the 16 contacts to the various detection sections. Some contacts independent, the rest in one or two groups The inputs of the independent contacts are connected to your central unit or one of your boosters. You only need to connect one input of the contacts that still make up a group to the desired source. The outputs of the 16 contacts are connected to the various detection sections. 16 fully independent contacts You connect all inputs to your central unit or one of your boosters. The outputs are connected to the various detection sections Detection section 3 (central unit) Detection section 2 (booster 1) Detection section 1 (booster 2) Groep 1 Groep 2 (c) 2008 Huib Maaskant Eddy de Boer intellibox booster booster Manual BMD16NSD version 1.2 page 14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ volgende module PWR BMD16NSD www.floodland.nl/aim naar centrale Sections without detection It is highly recommended to power track sections without current detection via four diodes. The diodes create the same small difference in voltage as the contacts of the BMD16NSD. Trains will be better detected at the edge of the detection sections. This practice is recommended for all current detection decoders, not just for the BMD16NSD. Connecting a reversing loop In a reversing loop, the loop module is inserted between the BMD16NSD and the central unit. The example shows a detection section (1) outside the loop and a detection section (5) inside the loop. The choice of contacts is random. The input of contact 5 is connected to the central unit via the reversing loop module. In this example a module by Lenz. Contact 5 has been configured as an independent contact and the track for contact 5 on the soldering side has been cut. Detection section 1 Detection section 5 Groep 2 Groep 1 (c) 2008 Huib Maaskant Eddy de Boer LK100 intellibox Manual BMD16NSD version 1.2 page 15
More information is available at www.floodland.nl/aim. Building the BMD16NSD is completely at your own risk. The creators do not accept any responsibility for damages in any form that might result from building or using this electronic device. 20082012 Maaskant en Eddy de Boer Manual BMD16NSD version 1.2 page 16