Balancing power to PS3 trucks, help.

Casey Jones2 posted:

The new MTH One-Gauge PS3 F7 AA set is using a tach equipped slave board in the trailing A unit...Just thought I'd throw that into the mix.

They're really using two separate and independent boards in those, so it would logically have a tach reader.

gunrunnerjohn posted:
Casey Jones2 posted:

The new MTH One-Gauge PS3 F7 AA set is using a tach equipped slave board in the trailing A unit...Just thought I'd throw that into the mix.

They're really using two separate and independent boards in those, so it would logically have a tach reader.

Not really as can't run them independently. Both A units have to be plugged into each other not operated as a lashup.

 

 

 

C. Jones

I guess I'd have to see more details on how that one is assembled, it doesn't sound like any of the existing configurations that I've worked with for PS/3.

I don't mean to beating a dead horse either, but probably the reason manufacturers haven't matched the rpm's of the motors, is that it would add more cost  to their bottom line and they run smooth, so why do anything else, but I am after efficiency.  Now, since I don't have this technology, I can't really say whether or not this is worth the effort, but I am willing to try and just maybe there will be a benefit, maybe slower speeds, longer runs for battery power and more pulling power.  After all, I have learned a lot more than I new before beginning this post, and that is worth something. Casey Jones, tell us more about the new PS3 double tach setup, what is with that? That sounds interesting. Bob.

Well I'll be darned.

I don't wish to tear open my brand new PRR F7's w/ PS3. So I shined a flashlight inside the trailing A and I see a tach tape (painted flywheel) and what looks like a tach.

 Looks like you could talk to Ray about a PS3 slave. I heard they don't offer them, but it appears they do make them.

Why go back to DCC when I have DCS!

Apples and oranges and you guys are forgetting you need independent motor FETs to control two motors. So more than tach and software.  Ps3 slave does use tach but again only tach motor of slave controls voltage. G

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If anyone reading this wants the PS3 master and slave electronics out of my Southern PS3 F7 ABA set, it's theirs for $350 OBO.  I have however removed the tether plugs (long story)…so one would need to re-attach new ones.

You're even welcome to come over to my place in maryland, have a beer, and remove it yourself.

Sorry, the term "smart decisions" means that software could do something reasonably intelligent, even though somewhat hamstrung by 2 motors in parallel. I'm not saying that anyone is doing this much more that probably averaging the responses in the QSI.

And to the other question, I did already answer it, that running a 2-8-8-2 Aristo mallet, it has 2 motor blocks each with it's own motors and you can tell by the chuffs that it is reading each motor's commutator transitions...

If I was to design a system, I most likely would of course jump to separate drivers for each motor, and then let the microprocessor handle both motors, so you could do smart stuff when one motor block slips, including have the prototype option of that actually happening.

What's the point of monitoring both motors if you cannot control them independently? Well here is an idea, if either motor slips (easy to detect) then reduce speed and then ramp up again... just like a real engineer would do. I can think of a lot of things, but this is all what if stuff, nothing you can do to change the programming of the systems as they stand.

You know, some people on this thread are genuinely interested in exploring ideas, and some just want to confront and put down.

I'm in the hobby to have fun and try new stuff... if I wanted to stifle ideas, I could go to a retirement home.

Greg

I love MTH now that PS3 has DCC

machiningfool posted:

What would be the best approach to solve this problem? Bob.

But can you define the problem?  If you get 1% more battery running time is that worth $350 of electronics...less the value of a beer?   How about 2% more battery time?  Etc.

From reading posts on OGR for years there's not much discussion about power efficiency and need-to-know about where the Watts are actually going.  With growing interest in battery power I suppose this will change.  Here's my take.  The mechanical output Horsepower vs. electrical input Watts efficiency of the motors used in these diesels runs about 60-70% at peak efficiency.  For example, here's a Mabuchi RS-385 which one might see in an O-gauge engine.  With 12V applied, peak efficiency is about 65% delivering 80 g-cm of torque spinning at 8200 RPM.  Do the math on your engine (gear transmission ratio, wheel diameter) to get scale-MPH.  Note how the efficiency drops off dramatically when you go faster or slower than the sweet-spot zone.

RS385 at 12v

Picking off more numbers this is 9 Watts of electrical power in, delivering about 7 Watts of motive power into the transmission.  So that's 18 Watts for two motors...and we know that you can easily be drawing an incremental 18 Watts of power off the transformer when the diesel starts pulling.  In other words for a typical O-gauge diesel pulling, say, 3 Amps (54 Watts at 18V AC command voltage), this motor would NOT be operating near optimal efficiency.  One would have to run some experiments but I'd guess that power wasted due to mis-matched motors is less than 10%;  if someone can provide a better guess I'd like to hear it!

In other words you're looking to save a few Watts.  You could save that much power just turning off smoke.  Or you could lower the volume and save a Watt or two.  And like improving MPG in your vehicle, acceleration/braking habits can improve efficiency more than 10%.  Are you using a mainline diesel for switcher duty?  The gearing is different to allow the motors to operate closer in the efficiency sweet-spot which I'd think could double running time rather than just get you 10% (or whatever).  I have no idea if manufacturers select motors to maximize efficiency...but you could.  If you have money and time on your hands perhaps investigate swapping motors.  It may require different electronics to drive, say, brush-less vs. can DC motors.  Or if you are the mechanical type you can swap in a different gear-box to operate at maximum motor efficiency for the speed that you most operate your engines.

So even if you had separate tachs and separate motor drive electronics (which itself consumes power that must be accounted for) I'm not sure you would see improvement in battery run-time. 

Is this PS3 on battery?  If that's the case and you're willing to muck around with the electronics, I'd think you could save several Watts of power by bypassing the AC-to-DC bridge-rectifier that's on PS3 boards.  Since PS3 boards can run on DC, it seems you could save the lost power in the diode drops.  So 3 Amps dropped "unnecessarily" across two 0.7V diodes is 4 Watts.  I'd think that is more power saved than a motor balancing scheme.

All this just my opinion of course...

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Dah..... I just seek the truth! Dah.... no lies!

Why do U want to fight? I am a saint, I think, in my own mind. I lead DCC development. Which wire is positive?

I just want to forward toy train development. Now that we're discussing things (MTH), let me attack you.... OK?

If you defend anything, I'll get my boys to attack you too!

That's my legacy. Who am I?

Why go back to DCC when I have DCS!

Well, I am truly impressed by the technical knowledge presented on this forum and, like I said before, I am learning more things that, for now,  am capable of comprehending, but, I am learning.  I certainly appreciate the presentation of Stan004, that graph puts things into a logical perspective.  Maybe Gunrunner was right, I am looking for problems that don't exist.  When I get my layout finished, I will  do some tests, for my own amusement, to prove that,  I am looking for problems that don't exist.  Thanks for all of the input, and keep it coming.  Any kind of knowledge is good, whether it be positive or negative.  One great inventor said, "Even failures are good source for learning". Bob.

Engineer-Joe posted:

Dah..... I just seek the truth! Dah.... no lies!

Why do U want to fight? I am a saint, I think, in my own mind. I lead DCC development. Which wire is positive?

I just want to forward toy train development. Now that we're discussing things (MTH), let me attack you.... OK?

If you defend anything, I'll get my boys to attack you too!

That's my legacy. Who am I?

And I'm done here....

I love MTH now that PS3 has DCC

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