FM wireless mounted at loco is working! must see..stans video!

Did you try a 1uf non-polarized cap across each of the motors?

no.. do you prefer across the 2 terminals or a cap each from the terminal to motor case?

Your first photo is hilarious - a true LOL.

What exactly does the noise sound like, does it change with speed?  Can you post an audio recording?

I'd start try smaller caps across the motors - say 0.01uF if you have them.  The PS motor drive electronics uses high-frequency pulses to drive the motors and a 1uF capacitor would appear as a relatively low impedance shunting the drive current.  Put them across the motor terminals.  The motor case is electrically connected to the frame/chassis which connects to the noisy outer-rail. So putting a capacitor to the motor case would create a round-about current return path back to the motor drive circuit which I don't think is what you want.

So you're going to place the transmitter back in a dummy unit?  How will you access the battery and on/off switch? 

Presumably you're running wires from speaker to a dummy.  Neither of the PS2 speaker outputs are "ground" and there are endless stories of mis-haps where a speaker wire touches the frame and poof...there goes your audio amp.  So I suggest you add, say, a 1000 ohm resistor (any wattage) to each speaker terminal, then run the wires back to the dummy.  If one or both tether wires get pinched and touch the frame or whatever, the current will be limited and you should not pop the amp.  Then on the dummy side, put a 0.1uF cap across the two wires before going into the transmitter.  So in addition to gaining protection, you have a simple R-C low-pass filter of about 800 Hz which should adequately pass diesel rumble.

Does your stereo tuner have a "MONO" button to disable FM stereo?  This is far-fetched but FM stereo encodes left-and-right using sub-carriers that might interact with the high frequencies generated by the PS2 motor drive...in your photo the transmitter is sitting on top of a motor!  Putting the receiver into MONO mode disables the circuitry which looks for these sub-carriers which might eliminate the noise IF that's what it's from.  Again, it's a long-shot but it only takes a single button press.

I'll bet you'll never see someone try that with a legacy loco

I'm pretty sure you would loose that bet. FM shows the idea could work. I think today Bluetooth would be a better choice to avoid brush and pickup roller noise.

Pete

with remote vol all the way down and i move engine ahead i hear the best described as a low frequency scratchy noise through my stereo.turn up the vol at my remote to normal level and i can barely hear the noise but i know it is there. with engine sitting in neutral and i raise labor rev up i dont get the noise. i did install caps[from a spare computer board laying around that said 104/ .1uf maybe? on them] from each motor terminal to motor case but still have the noise. even with all this a great pleasure to listen to. i will try the mono mode next.

Roller Pickup noise is a problem with FM, likely a higher amplitude than motor noise. Try drop of WD 40 or better yet Atlas Conducta Lube on the rollers and try and get the track as clean as possible. Its diificult to eliminate completely though. Its more obvious when using a video camera that transmits to a TV.

Pete

i am 2 rail...cant lube the track..pulling to heavy..wheels would slip.

Sorry, I missed the 2 rail part. 

Pete

 i see the confusion on noise. prior i had the treble @ my amp up and it enhanced the the noise from the tweeter. the adjustments now are with the treble off and bass full on. i reinstalled the tweeter and used the same settings and it now the tweeter has very little effect. the noise is best described as listening to an AM station but nearby lightning causes static...i will ck my pile for an audio transformer..plenty of room in the loco for one.

Well, curiosity got the better of me so I found a FM transmitter module probably similar to what you have and wired it up to a PS2 diesel that happened to be opened up. 

I simply attached the speaker terminals using alligator jumpers directly to the transmitter 1/8" connector and put the transmitter in a gondola as shown in the video.  I had to turn down the volume of the engine to "50" since anything above that seemed to clip at the receiver.  This makes sense since the PS2 audio uses 5V and audio devices often want "line-level" signals which is typically 2V.  The video starts out with "just" the PS2 engine speaker...then at a few seconds in I turn on the FM receiver with amplifier.  The video does NOT reflect the room-shaking volume of this method. I could not detect any noise when the engine started moving forward or reverse.  I turn off the amp again a few seconds before the end of the video.

People casually throw around terms like "awesome" but I must say the effect is indeed awesome!  

Anyway, this transmitter only has 4 frequency choices and even without the transmitter on the stereo light came on in the receiver presumably from local FM radio stations.  But there was one instance where it appeared the "Stereo" light was the result of the tiny transmitter and I think I heard a scratchy sound...pressing the "MONO" button and the noise went away.  I couldn't duplicate this so it may be a false sighting but give it a try.

Again, this was PS2 diesel and I don't have a PS3 to try it on but I must say it's worth the effort if you want to re-create that visceral sensation of a diesel prime mover rolling by.  Wow!

and sitting idling...like being in the switching yard..i now leave my enhanced sound on much longer..very soothing...

THIS IS AN IDEA IVE BEEN TOYING AROUND WITH, I WILL BUY A TRANSMITTER MONDAY AND INSTALL IT THIS WEEK. KUDOS TO YOU, WOW! I HAVE A SURROUND SYSTEM THAT WILL ADD SIGNIFICANT REALISM TO RUNNING TRAINS.  CLIFFORD

the one in the picture came from the auto section at wal mart/ 13.97..got good reviews..part of my noise issue might be a 30 year old pioneer receiver.

I realize there's some logistics to getting it installed and wired-up.  And, yes, what if you have multiple engines etc. etc.  But now that I've heard it for myself, I guarantee that if you have a visitor who typically nods (yawns) politely when you show them your layout, this will blow their socks off and they will wonder when they get home why their socks are missing! 

IIRC I got my transmitter for less than $5 on eBay several years ago.  This is the best bang-for-the-buck enhancement I've seen in quite a while!

I was waiting to hear the horn blow.

 stan asks So you're going to place the transmitter back in a dummy unit?  How will you access the battery and on/off switch?

the transmitter has a slide switch but with the unit in the dummy the switch will be inaccessible. i may interrupt the battery pack[2 aaa cells] and use a small on/off switch. my dummy has constant voltage lamps...any ideas where to tap into to charge a pair of 1.2 v ni-mh batteries?

Why not just use track power with a DC power supply and a supercap to ride out the power interruptions?  Why fool around with batteries at all?

that is what i am thinking as well...my dummy unit has constant voltage lights..2 large heat inks w/ caps and circuitry as well..is there a clean dc 3 volts there someplace?