BlueRail card (use) for Old School American Flyer Trains.

I have done few but they were newer with can motors.  Apparently, just a rectifier might work.  If you have the board or other PWM supply, bench test it.  I would imagine without a low pass filter, the motor might not run smooth.  The bluerail board has a 1.2 amp continuous rating with various length peaks to 8 amps; I don't know what an AF AC motor would draw in this instance.

Brendan 

The Gilbert American Flyer motors (except for a few made as DC) are series connected universal motors. They run equally well on AC or DC. A Gilbert steam engine with light, smoke and choo choo pulling say 6 freight cars will draw a continuous 2A. I would recommend you try it and see if it works. The engines are reversed by changing the direction of current flow through the field relative to the armature. The Gilbert reversing units make the automated wiring changes. There are modern electronic units that can replace the original mechanical reverse units. The ones rated 5A are adequate for the AF engines. I am not familiar with the Bluerail boards so I do not know if they have the reversing feature built in or if you will need the second board for direction control. I hope it all works.

I suspect that the current Bluerail board is a bit anemic for this use.  It will only supply a 1.2A continuously.

Overload Protection: The BlueRail board contains circuitry to protect itself in the event of a current draw overload. Please refer to the graph. The red line indicates the point at which the BlueRail board shuts itself off. The board will tolerate an 8 amp draw for .4 sec (before shutting itself off). It will tolerate a 4 amp draw for 1 second, a 2 amp draw for 15 sec (continuous), a 1.25 amp draw for 1 min (continuous) and a 1.2 amp draw continuously. A locomotive with a 2 amp stall current (green line) will typically draw 2 amps of current for the first few seconds it starts to roll, before stabilizing at a much lower current draw. Pulling heavy loads up steep long hills and lots of lighting will increase current draw. Please consider these values when deciding if this board is appropriate for your locomotive and layout.

Unfortunately Gilbert AF motors do not have 3 wire fields. All these diagrams show a center tap field despite the introductory comment about 2 wire fields. 

I'd experiment, but unfortunately, I don't have any old Flyer locos handy.  

Brendan

Brendan,

I cut 'n pasted in an excerpt from that Digitrax article below.  It looks like 3 wires from the motor coil or field instead of two.  Right?  Are they assuming you rewind the field coil and in doing so bring up a connection mid-way from the magnet wire used to wrap it in order to gain a "center tap"?  So effectively you divide the field in half with power flowing one way through one half and the other way when polarity is reversed through the other half.   Thanks. 

This example shows a wiring diagram for an AC universal motor with two-wire field coil. For this type of motor you must add a bridge rectifier to control the polarity to the motor's field coil. This type of motor is found in AC locos built from the 1950s through today.

I looked at the Digitrax website and saw what you posted. I believe Digitrax has an incorrect drawing posted, it does not match the italicized text. What it should show is the field in series with a full wave bridge rectifier that has the armature connected across the center of the bridge. This arrangement will reverse the direction of a Gilbert universal series motor if the decoder changes the polarity of the orange and gray wires when a direction change command is entered.

Center tapping a Gilbert motor field would result in a non operating or poorly operating engine that would likely fail from an overheated field winding. The simplest way to do this it to buy a replacement DC can motor. Drop in kits are available for Gilbert engines. It also lowers the current draw so the 1.2A decoder will work. These kits can also be purchase with a half speed worm gear for a more realistic speed range.

Given what Tom said, the drawing is wrong.  Its all academic if the the whole shebang draws more than 1.2 amps continuously.  Put a can motor in it and don't look back.  If the draw was low enough, you could probably connect the decoder before the reverser and let it do its thing; you'd control like it was on AC.

Brendan

Thank you to everyone who responded! I knew going into this that the Bluerail board would not be able to provide the current that these old motors require. I think I can take care of that. As everyone pointed out, it's the possible incompatibility with the pulsed DC output and the old motors that is the challenge.

I don't think I want to swap out all of the motors of my engines, so at this point I'm not really considering doing that. I really thought it would be a lot of fun having many different trains running under separate control, which the Bluerail card will do. I know of the other company out there that will output AC and up to 4 amps, but it is not smartphone compatible.

So if anyone else comes along who has done this, please let me know.