Control Your Locomotive with Radio Waves and Battery Power
The Dead Rail System
This page is dedicated to the memory of
Mike Pfulb of Mike's Backshop
Dead Rail Pioneer and Master Craftsman
who passed away in February 2015
My On30 Bachmann Forney (Tsunami sound version) with a DRS1 installed. The blue LiPo battery is just visible inside the cab and the receiver is just visible at the back of the tender. A spare receiver is shown next to a quarter for size comparison.
Are you tired of cleaning your rails? Are you overwhelmed by all the wiring needed to power your track with DCC? Then Wireless DCC may be the answer for you. Take an existing DCC system and add the DRS1 system to your locomotives and send commands to them over the air and power them with Lithium-polymer (LiPo) batteries. It is amazing how much better locomotives perform on battery power.
How does it work? The DRS1 transmitter takes the DCC signal right off of the DCC bus and tranmits it by radio. Receivers in each locomotive then grab this signal and recreate DCC onboard the locomotive using a battery for power. The DCC decoder on the locomotive then uses this DCC power exactly as it would from the wheel pickups. The big difference is that the power is not interrupted by dirt and corroded wheel pickups so there is uninterrupted power. The downside is now you need to keep yoour battery charged. More on how to do that is to be found below.
PDF e-book about Wireless DCC Dead Rail. It has schematics and construction tips in the back.
Youtube video featuring the talents of Craig Bisgeier and a quickie DRS installation. It took us about 30 minutes to install the DCC decoder and the DRS1 receiver with a 500 mAh battery in this IHC 2-8-0. The biggest problem was identifying the wires inside the lcomotive (they were all "color-coded" black). We clipped the wires to the wheels and connected them to the receiver. The motor wires were connected to a generic DCC decoder. We did not use a sound decoder but there are no issues with sound decoders if you have one.
What is inside the Forney?
In this photo I pulled out the wiring harness for the DRS system. This is the most basic system wih just a battery and the DRS1 receiver. The battery goes in the cab and the plastic coal load covers up the JST connector. To turn off the locomotive, I remove the coal load cover and pull the JST connector apart to disconnect the battery. It is necessary to turn the battery off as running a Li-Po battery to zero will damage it.
Charging is done with the charging jack. I just pull it out of the door with a tweezers and connect it to the charger. It takes about 15 minutes to fully charge the battery. The battery will last for several hours of normal operating. I recharge the battery before each operating session. I have yet to have the locomotive run out of juice during a session.
Here is a close-up of the installation point for the DRS1 receiver to the decoder board. The pickups from the wheels go to points labeled L (left) and R (right). I cut the wires coming to these points from the wheels (after I verified with my ohmmeter that they led to the wheels). There were two wires to the front drivers and two wires to the rear truck. I then soldered on the leads from the receiver DCC output. The other end of the receiver attaches to the battery and you are ready to go!
Magnetic Reed Switch for Easier On/Off
Opening the coal load to disconnect the battery was not very elegant, so I decided to try adding a reed switch. A reed switch uses a magnet to control it. I also didn't like the idea of having to hold a magnet next to the reed switch to keep it on or off - what was needed was a way to just pulse the reed switch briefly and have it latch the power on or off. This can be done by connecting the reed switch to a handy little board from pololu.com, the Power Switch SV. I wired the reed switch in place of the pushbutton Pololu supplies with some flexible 30 ga. magnet wire. By tapping the reed briefly with a magnet the locomotive turns on. Tapping the reed again and the power turns off. I taped the reed switch to the bottom of the roof where it is neatly hidden. By tapping the roof with my magnet I can turn the locomotive on and off. The magnet is attached to a small screwdriver with some heat-shrink tubing. Very neat! Another advantage of the Pololu Power Switch is that it can switch several amps of current, whereas, most reed switches (and indeed most small slide switches) are rated for only a few tenths of an amp.
Batteries
Here are some examples of LiPo batteries. These are "flight" batteries for small R/C airplanes. I have found that 2-cell 7.4V batteries will work with a Tsunami sound decoder with no problem. In my Forney this works nicely as I rarely pull more than 4 cars with it. However, if you are going to pull a long train then you proabably want to use an 11.1V 3-cell battery. 4-cell 14.8V batteries will exceeed the voltage limit of the DRS1 receiver.
The small batteries last for a lot longer than you might think. I put my Forney in a box and set the throttle to 25% (which is fast as I ever run it) and let the wheels slip. A 2-cell 7.4V 240 mA battery lasted for 1 hour and 20 minutes! In the test, the can motor in the Bachmann Forney plus sound was drawing about 200 mA continuously.
In the photo several batteries are compared to an HO scale boxcar and a DRS1 receiver. Clockwise from the upper left are 120 mAh, 350 mAh, and 450 mAh 11.1V Li-Po batteries.
Charging from the Track
I have been working on charging from the rails. It turns out to be trickier than it might first appear. The charger must contend with the both the battery charging and the locomotive drawing current at the same time and this complicates things.
I have found that a good system consists of 3 portable phone batteries in series - that is 9 1.2V NiMH cells - charged by a 20 Ohm 1/2 Watt resistor in series with a diode (cathode towards the + end of cells).
