How to convert fastrack switch to Command Control

Why did you have to buy the motor driver board if they didn't need to make a new one?

  I bought the new Motor Driver board for convenience and proof of concept.

  I do not know what functions ElectricRR's designed board are to perform.  I made my decision before making a more careful analysis of what it would take to use the current Motor Driver board. Adjusting the current board's output voltage down to 5V is pretty straight forward.  The Radio PCB probably draws very little current and you get away with a very small +5V supply that is external to the old Motor Driver PCB.  I would have to take current measurements to confirm that hypothesis. 

  The second variable would be the compatibility of the command to switch, coming from the new Radio PCB, and interfacing this with the requirements of the old Motor Driver PCB's input. I do not know if we have a logic output, contact closure, short to ground, ect.

  If the output of the Radio PCB and the input of the old Motor Driver PCB were incompatible without a simple solution........that would require a special PCB.  That PCB would have to contain both the interface and the required +5V supply.  It might  be more cost effective to just buy a new Motor Driver PCB, which will interface very nicely with the new Radio PCB straight forward pin to pin and is already +5V compatible.  Just add the home made interconnecting cable.

Me toooooooooooo

From a practical point of view, I am trying to decide if I should go through the trouble to add the data terminal to my 4 converted fastrack switchs or not bother. It would cost $3.10 per switch.  No info in the manual as to the uses for the data terminal. 

Gunrunnerjohn had this to say about the data terminal:

Here's a reply I've found, though I haven't actually tested it, I believe it was from a Lionel person on their blog.

It is the data and com line, similar to the command base cable used to drive devices such as ASC/AMC/ARC, etc. The Data terminal is essentially a +5VDC communication line used to drive the old IC Controls line of devices, so a cable does not need to be run from the command base. If a command switch is in a close proximity to these devices you can use DAT and common to drive those devices.

Thank you John.

What I don't know is how popular is the use of that data terminal.

I haven't even verified if this is true, but it kinda' makes sense.  Since the serial data link from the command base is somewhat of an Achilles Heel for some folks configurations, having it distributed is kinda' neat.  This would allow you to have stuff like a TPC, BPC, etc. remotely and not have to run the data line back to the command base.

  Current drain of the Radio PCB at +5V is about 5ma.  Not very much, but I could not find a +5V source on the old Motor Driver PCB.  The 5V Voltage Regulator on the board did not measure +5V in reference to ground and that is what is needed.

  With the new Radio PCB facing you and the white PCB connector to your lower right and antenna lead to your left, I will call the terminal furthest from the antenna lead terminal #8. I connected that terminal #8 on the Radio board to the terminal marked OSW on the old Motor Driver PCB and Terminal #7 of the Radio PCB to the Motor Driver PCB terminal marked TSW.  I connected #5 of the Radio PCB (Ground) to the (GND) terminal of the old Motor Driver PCB and also to the negative of the external 5V power supply.  I connected #4 of the Radio PCB (+5V in) to the positive of the external external 5V supply.

Viola!!!! 

  The switch works perfectly with the OLD MOTOR DRIVER PCB and saves the cost of $23 for a new Motor Driver PCB and settled my compatibility pinout questions between the Radio PCB and the old Motor Driver PCB. My guess now is that the soon to be released ElectricRR PCB and conversion kit is little more than an external +5V supply and perhaps some way to address the need for a blinking LED to indicate programing in progress.

  I will now research a cheap way to get that +5V that is needed by the Radio PCB.

  The +5V power supply can consist of 3 components, a diode, a cap, and the voltage regulator. I built one for less than $3. Any silicon diode rated at 50V, 100 ma or more will due. I used a 220MF cap rated at 35V.  The regulator I chose is a NTE977 (+5V, 100ma). You can build this power supply even cheaper than this if you buy in bulk and shop for a generic voltage regulator on ebay. Do not use a bridge rectifier because one side of the AC source (track voltage) and the negative side of the 5V supply are common. I powered up the Radio PCB and it worked fine with this simple supply.

  I will next address the track LED problem, since the old Motor Driver PCB does not provide for this.  What I have found out so far, is that pin#2 of the Radio board outputs a constant +2.2V until the programing push button is activated.  It then cycles from +2.3 to near zero.  You can not use that to power the track LED directly because of the current required. As it looks now, the total conversion to command control for the fastrack switch should come in for under $25. The greatest part of that cost is the $18.60 for the missing Radio PCB from Lionel. 

To address the LED problem, I did the following: 

  I used the cheap and simple (3 component) +5V power supply I described earlier as my power source for both the Radio PCB and the track signal LED. 

  Connect from the +5V a 200 ohm 1/4 watt resistor to the emitter lead of a 2N4403 PNP switching transistor. Connect the collector to ground.  Connect the base lead through a 10K ohm 1/8 watt resistor to what I called the #2 terminal of the Radio PCB.  Remove the LED lead going to the OLD Motor Driver PCB connector (marked MOT+, MOT-, LED, GND ) and connect it instead directly to the Emitter of the 2N4403. ALL DONE!! (3 components).

How the circuit works is this way. The transistor is in parallel with the LED. It does not normally conduct and thus the LED stays lit and is current limited by the 200 ohm resistor.  When the programing push button is pressed and held for a few seconds, an intermittent signal from the Radio PCB will arrive through a current limiting 10K ohm resistor to the base of the 2N4403 and turns the transistor on and off thus shorting and un-shorting the LED causing it to blink and indicate that the switch is accepting programing.

Dirt cheap. 2N4403 $0.40, 200 ohm $0.50, 10K ohm $0.40. and much cheaper still on eBay.

If someone would like, I can draw up the 2 schematics for the +5v supply and the LED driver.  Otherwise I think I'm all done with the conversion project.

It sure was fun