American Flyer Zombie Rail Conversion from e

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American Flyer Zombie Rail
Conversion from AF e-unit to aircraft RC 2.4 GHz

My name is Doug Stoll and I have been interested in S scale since 1973 when I purchased a Pikemaster set for my then two year old son at a flea market auction for 15 dollars. I became a member of the Badgerland-S-Gaugers, BSG webmaster in 2004 and a NASG member in September 2023.

In 1978 I became interested in remote controlled aircraft which became my focus for many years. A few years back I purchased a damaged 0-8-0 K5440T set with combine, searchlight car and crane. After repair of the set I got the bug to repair more from eBay and start running them. As a retired Senior Manufacturing Engineer at Harley, I recognized that nothing stays the same and there is always room for improvement. I had RC controls, left over hardware, and assembly knowledge for models that would fly, so I asked myself: Could the same systems work for my rebuilt flyer collection without creating a situation that there was no returning from? So it became a reliability mission to be able to get rid of tender thumping, going backwards to go forwards, and dirty track issues and still allow a means to return the models to the original state if necessary for resale if desired.

In 2019, I began a short-line layout (figure 1) that would encompass the city and towns of my old neighborhood. The CSTPM&O (the Omaha) ran right past my wife's house in Jim Falls Wisconsin and through Cornell where I went to school. I remember watching the trains when we went to the grain mill for milling dairy cattle feed. I still remember the taste of molasses as I sampled it going into the grain. This memory taunted me to create a web page regarding the short-line route. Next on my things to do list was recreate the line in 1/64^th scale.

At the June 2023 club meeting of the Badgerland-S-Gaugers, I brought three samples of "Dead Rail Locos" that recharge while running on the rails hence the term "Zombie Rail". The system uses original Gilbert motors (can motors will work also) powered by three lithium ion batteries (18650) for 12.6 volt power. This hardware (figure 2) will fit in the tender of a steam engine or using the AA size batteries (14500) will fit in the main body of the Baldwins, Geeps, and steam locos with a smaller tender like switchers. The 18650 size cells are typically used in your laptops or cordless drills. The smaller 14500 cells are used in some rechargeable flashlights. Both types are available online. I typically dissect a new laptop battery which yields 6 cells for two locos and costs much less than separate purchases.

The new electrical configuration allows the track power AC or DC, 12-15 volt, to travel through the AF pick-up wheels, into an 8 amp bridge rectifier, to a three cell (3S) BMS balance board that evenly charges the cells with a 5 volt max limit for each cell to prevent overcharging. The batteries are also series wired for the DC converted motors (figure 3) which results in 12 to 15 volts DC for the drive system.

The available current then goes though a switch to the brushed 15 amp ESC (electronic speed control), which provides controlled DC power to the motor. The ESC also provides a BEC (battery eliminator circuit) that provides 5 volt power to the 2.4 Ghz receiver for the radio control portion. When connected in this manner, the receiver controls the motor speed from the brushed ESC that is set on airplane mode. Direction is controlled through a 15A DPDT non-latching relay wired like some AF steam manual directional units that came without an E-unit. The relay is activated by the head light wires provided by the model car portion of the ESC. From the relay, DC power is then provided to the motor. I placed a slide switch under the tender that connects or disconnects power to the ESC for operations. The battery circuit allows charging through the rectifier and BMO balance board while track power is on and not drain the batteries when operations are over. The slide switch button has a hole drilled in it allowing a push-pull action with a wire nail. The head was painted red representing an air valve knob. Plans are to cast an air tank and tool box similar to the Geeps to give the handle some realism and purpose.

The hardware that needs to be removed should be placed in a freezer bag or similar container (figure 4) and labeled for which unit it came from in event that you wish to return your unit to stock form. The new hardware fits inside the tender shells without any issues if certain protocols are kept. If tender shells are metal, insure that no shorts are possible with insulation. Heat-shrink tubing covering the ends works well. The 18650 batteries fit into the shell around the coal form dent in the front in the plastic tender shell.

Place two batteries with positive forward in first in typical steam tender (figure 5). Hot glue the first two batteries where the third battery would contact then place third in negative forward. When cool the set can be pulled out to wire in series and connect the BMS. When components are wired (with connectors or direct) the batteries get a drop of hot glue on upper edge to keep them in the shell. Follow with the rectifier double sided taped to the tender rear, terminals down. Stick the ESC with the tape to side of tender as far forward and deep as possible allowing the wires to the receiver to wrap around the rear of the shell. Slip the receiver in the other side along with the relay between taped at the bottom to prevent it from dropping into the metal frame. Hot glue a half inch square piece of metal one inch back from front cavity to prevent the contact of the front truck rivet solder from eating though the insulation of the battery avoiding a possible short. The switch on the lower part of the frame was modified with the wire nail and 5 minute epoxy was used to allow removing without major difficulty. Place a small piece of tape over any hole in switch body where epoxy can infiltrate and prevent movement before gluing it down. Make sure trucks move without interference.

The Baldwin (figure 6) and Geep (figure 7) use the smaller 14500 batteries due to restrictions of space. Assembly is similar as the steam unit except placement. Batteries are dropped in shell where the e-unit was hot gluing each one where it contacts the last one allowing the set to get removed for wiring. The socket for original light may need to be removed on Geep. LEDs can be wired for cab light (signifying power on from receiver) and directional by power to motor.

Using the aircraft transmitter controller, the operator can use most controls available on the unit. The top left toggle switch (on upper left top of transmitter control for flaps) controls loco direction. Left control stick is up for full throttle and down for stopping just like a plane. Trim for this feature can also leave the headlight on.

The other features of the controls run through a circuit board consisting of a receiver, relays and 9g servos (figure 8). Each receiver can be paired or bound with the service loco assigned to the location. In this case left side movement of the left stick provides bell (12v through relay to a '65 mustang flasher driving a danger bell accessory), while right movement of left stick provides diesel horn because this area is serviced by a Baldwin. The controls right stick can control two accessories with 4 functions. In this case, move right stick to the right and a log loader operates while up movement dumps logs onto loader. Left movement of right stick activates the barrel loader while right movement unloads a truck from a flat car. The 6th channel switch (front upper left) transfers the control of which group of accessories that are controlled by the right stick by redirecting the relay ground systems. Power goes to both sets of relays, but the ones with active ground become live. In this case there are accessories on the left of the upper west layout called the dairy farm. Again right stick with left movement actuates the cattle loader while down activates the cattle in the car. Left/down diagonal movement operates both simultaneously. Right stick right movement actuates the loading platform with hay bales into an action car while up movement unloads the car if needed like milk cans returning to the farm. The location of this activity is from one of the towns (Holcombe) on my layout serviced by Baldwin 21801. Each town or village has its own service loco and each of the town's individual relay board receivers are paired with each servicing loco. Next stop going south is Cornell which is serviced by GP 371 and is a stop for passenger service and parcels as well as paper mill, feed mill and scrap-yard. After leaving Cornell, the main line goes to around the wall to the lower level at a similar decline as the Gilbert trestle set. Reaching the lower level on the short line of the pike is Jim Falls serviced by Baldwin 355 (lumber mill, cheese factory, pickle factory), Leaving Jim Falls the rails pass the Annual Sturgeon Festival where rails run behind Lionel carnival equipment to satisfy scale perception. Then back to the beginning of the short line which is Norma that houses the staging yard serviced by a 343 switcher. The roundhouse, coal loader for locos and water-tank are controlled by the main line controller. Left stick for bell and whistle while right stick controls water tank, coal loader and roundhouse turntable. Operator can deactivate and activate the loco of choice at the yard roundhouse or program individual locos into the control. The actual short-line which includes the towns on my layout is described in my web on CSTPM&O at www.trainweb.org/omaha/.

The channels of the radio that is used control how many accessories to activate per model. The specific model of radio control transmitter you use, determines how many models you can select. I prefer Spektrum Radios and I use a DX7 (gen1) and a DX4e. The DX7 has the ability to select up to 20 different individual models and display model or city name on LCD screen. The operators can activate any of the locos and the one you select is the one you control with a different frequency. Some manufactures have the same frequency and changing models only controls the trims and curves of the stick movement. The Spektrum gen2 DX7E has 250 model selections, so the sky is the limit. The DX4e controls only one model of choice which is okay for main line use.

All components can be purchased at electronic supply houses like Digikey and/or eBay. I have used batteries from cordless drills and laptop replacements. The replacement laptop battery provides enough cells for two steam engines (6 cells). AA size can be purchased through eBay. The bright side is reliability and consistent power even through switches and dirty or surface rusted rails, and no more tender-thumping.

A used DX7 Generation 1 transmitter runs about $120, the DX4e runs about $50 dollars, and the loco upgrade also runs about $50. Train hardware can be returned to original state, and transmitters can be used for helicopters, planes, cars, boats or for whatever you can imagine.

I have incorporated a volt-meter on the track fascia to measure available voltage used. When the engines are charging, you will notice a pulse or change in voltage. When it stabilizes, all the batteries are fully charged. I also put LED cab lights in locos powered from the receiver to recognize when they are activated preventing draining. Lithium cells run from 4.2 max, to 3.2 min, with 3.7 as storage level. It is important to charge with no more than 5v per cell. Overcharging will cause overheating, and undercharging will cause degrading of the cell, and would lead to permanent inability to reach full charge. Never charge the Lithium cells in series; an example of this would be a series wired battery pack of three connected to a trickle charger power supply without a BMS protector in a balance board. One cell can reach 7+ volts and burst into flames while next cell may never get a charge causing it to die. They are safe as long as rules are followed. After all, you don't want to become a zombie yourself!