Wireless DCC Radio Conrol and Battery Power for Model Railroad Locomotives
by Duncan McRee, Ph.D.
42 pages, pdf format
This book details installing the Dead Rail wireless DCC system in locomotives. It includes a discussion of wirless DCC, which batteries to use and how to charge them, considerations about radios and getting the best reception. Even includes schematics and parts lists for building your own radios and transmitter (its surprisingly simple with the already completed radio modules used).
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Presentation about Dead Railing My Own HO/HOn3 Donner Summit Layout
I gave a clinic at the 2015 Pacific Coast Region meet on my Donner Summit layout. The slide deck is just the pictures without my verbal explanations but it does have lots of pictures of installations. It also shows my own fully operational Dead Rail HO/HOn3 multi-deck layout of which I am very proud :) I will be giving the clinic at the Portland National Convention this summer.
Gold-plated Breakaway Connectors - I use these to make connections between the battery and the receiver. They are small, easy to plug and unplug and electrically reliable. Receptacle - Digi-Key SAM1115-32-ND. Header - Digi-Key SAM1111-32-ND.
Litium Polymer batteries - The best source is Dead Rail Installs (see above in Installers list for info). All RC stores that carry small electric airplanes and helicopters will have small 3-cell batteries. They can usually be made smaller by cutting off the heavy casing and adding a smaller connector made from breakaway headers (above). these batteries usually do not have circuit boards built in to them to protect them from over-charging and over-discharging.
Portable phone batteries. These are usually 3-cell NIMH bateries and are available nearly everywhere including drug stores for a good price. Connect 3 packs in series for 10.8V. Can be trickled charged from DCC by suing a diode ans a 20-Ohm 0.5Watt resistor. Details are in the DRS Book.
Battery Charger. I like the HiTec X1. It can charge just about anything. It is not easy to use but then none of the better battery chargers are - they are just too complicated. I got mine by searching amazon but most RC stores have them and the helpful person behind the counter may be able to show you how to set it up to charge the battery you just bought.
Electronic Switch - You need a switch rated at least 1.5 Amps to turn the battery on and off. These can be quite big and bulky. I often use a shunt (jumper) across the pins of a breakout header. An alternative is to use an electronic switch. This has a small momentary tactile switch that is used to toggle the power - Pololu Pushbutton Power Switch. I have mounted the pushbutton so that it can be toggled by a bamboo skewer through a small hole or window. The board has a green LED so you can tell when the power is on for locomotives without sound.
Reed Switch - An even better power switch can be made by replacing the pushbutton on the Pololu Power Switch with a small reed switch. You can then turn the power on and off with a small magnet. The reed switch can be hidden inside the shell. A small reed switch is available from Digi-Key 374-1083-ND. Small super magnets are available at hardware stores. I taped one to a small screwdriver to make my "magic wand" for turning my locomotives on and off.
Flexible Wire - TCS sells small very flexible 30 ga. wire in multiple colors. Also useful is solderable magnet wire from All Spectrum Electronics.
Tam Valley Depot is a member and sponsor of the Dead Rail Society.
Wiring diagram for the DRS1 receiver. Wire colors correspond to wires on the harness.
The recommended battery is an 11.1V lithium polymer (lithium ion) 3-cell battery of 100 mAh or higher. In a test I found that a 120 mAh battery will run my sound-equipped Forney for 40 minutes with the wheels slipping. Obviously, the larger the battery the longer the time between charges. 7.2V, 2-cell batteries will work with most locomotives with some loss of pulling power.
An on-off circuit to disconnect the battery is needed. This can be a plug you pull apart or it can be switch.
If a lithium battery ledt connected after discharging it will be damaged. (Some batteries, like the SparkFun batteries reccomended below, come with a small circuit board to prevent this and to prevent over-charging.)
Be sure to read the instructions that come with lithium batteries - they are not as tolerant as other types of battery.
We recommend removing your battery and charging it in a coffee cup as they have been known to explode. If you cannot remove it, then charge it at the slowest rate possible on your charger.
Dimensions of the DRS1 receiver. It will fit in HOn3 and up engines and tenders. For N scale it can fit in a boxcar on a slant.
Frequently asked DRS1 questions: Q: Can I consist DRS1 equipped units with my conventional DCC locomotives? A: Absolutely. The DRS1 locomotive receives and obeys DCC commands as if it wre still connected to the track
Q: Can I program decoders in DRS1 equipped locomotives through the transmitter / receiver connection? A: Yes, with Programming on the Main (Ops mode) you can program your locomotive. However, some decoders (e.g.Tsunami) will not allow changing the loco address in Ops mode. In this case you can attach the the decoder directly to the pragramming track. The DRS1 has a plug that can be removed and connected to an adapter to make this easier.
Q: Can the receiver send commands and power to more than one decoder? I have several locomotives with separate sound and motor decoders A: Yes. You can attach as many decoders as the current limit will allow.
Q: What about automated control from cab bus equipped modules like NCE mini-panels, loconet, xpress-net, NMRANet etc. A: These are all cab-bus or accessory bus devices. The DRS1 does not change the way the cab-bus behaves in any way - it is connected on the track side of the command station.
Q: Can I still run these equipped locomotives at my club or friends layout? A: No problem. Simply bring along your DRS1 transmitter and attach it to the track with some alligator clips in an out of the way location. You can now use your freinds throttles to run your wireless DCC locomotive (be sure to run it on the floor just to show off!).
Q: How many receivers will one transmitter accommodate reliably. A: There is no limit. The receivers do not draw any power from the transmitter.
Q: Is there a way to prevent locomotives from continuing to run all the way to the floor if they do leave the track, A: Yes, grab them. This is a portential new danger for on-board battery power (and keep-alive circuits).