# Detecting Engine Load



## eheading (Jan 5, 2008)

I have been seeing posts that imply that the QSI sound system does a better job of detecting engine load than does the Phoenix system, because it can detect changes in load on the motor not just the input voltage. I believe that this is based on our intuition (mine included) that says when we get on a hill we increase the throttle to maintain speed and hence the "motor" is under greater load. However in a diesel (electric) engine, the engineer does not control a throttle on the diesel engine. What he controls is an 8 position rheostat for the electric motors, and the diesel engine responds the load resulting from his rheostat position. 

So it seems to me that the way Phoenix detects loads on the engine, by voltage/current changes to the electric motors, is exactly the way the "big boys" do it. Am I misunderstanding something here, or is this correct?? Please don't think I am picking on the QSI system, I am just trying to understand what happens in the real world.

Ed


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## lownote (Jan 3, 2008)

Are you saying that the sound of a diesel engine doesn't change under load? Is that true? I really don't know.


With QSI when the loco hits a grade the sound of the engine changes. When you increase the throttle it changes again. If you increase the throttle on a level grade, the sound of the engine is different than when you increase the throttle going up or downhill


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## Semper Vaporo (Jan 2, 2008)

The Diesel engine governer attempt to hold the engine running at one speed. As the traction motors draw more current the generator has more current flowing in it which creates a magnetic field opposite to the field that is creating the electric current. This reversed magnetic field slows the generator, so the Diesel governer increases the fuel to the engine to make it run faster (well, maintain the speed it is supposed to be running). Thus you hear the louder exhaust due to more power being used in the cylinders.


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## Greg Elmassian (Jan 3, 2008)

The Phoenix only senses voltage. That is all it can sense, because it has no connection to anything else. 

The QSI and the ESU, to pick two, have the sound processing and motor control in one package. They both sense the load on the motor by sensing BEMF, which is a reverse voltage that is proportional to the load. I can go into the technical part of what BEMF is, but they have it and it works. They also use BEMF for motor control, which allows finer control of motors. I won't go into the technical part of that either. 

Think of it this way, you put 12 volts on your track, and a single loco goes up a grade. 

Now run this loco at the same voltage with 2 cars attached. 

The track voltage is the same... so the Phoenix cannot tell anything is different. 

But if you had a BEMF decoder running in DC mode (like a QSI), it would also sense a greater load on the motor. This knowledge allows the decoder to do various things, like make the motor run more smoothly, slower speed running, etc. The other thing it can do is vary the sound not just based on voltage, but on load. 

By the way, the electric traction motors on diesels draw more current under load. 

I hope this explains the basics. 

Regards, Greg


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## eheading (Jan 5, 2008)

Greg, you are right, the diesel engines change sound as the electric motor draws more current. And when you add two cars to the locomotive at the same voltage (load) setting, the engine just runs slower. If you want to bring it back up to same speed as the lone engine, you increase the voltage on the motor. It seems to me that BEMF only comes into play if you have a "cruise control". Do the "big engines" have cruise control?? Also, if the BEMF tells the "controller" to increase the voltage due to increased load, monitoring the voltage will detect it.

The way the electric motor draws more current under load is when the engineer moves the rheostat up another notch, ie. increases the voltage on the motors - just like the Phoenix does.

Now, does the modern diesel have a "cruise control" that tries to keep the wheels running at a constant speed? Even if it does, though, somewhere it has to increase the voltage to the traction motors to increase the load. If you measure the voltage going to the motors, this is the same thing, isn't it?? Again, I think we are confusing a diesel engine and an electrical motor. All the diesel engine is doing is providing voltage/current to the electrical motor. Still seems to me this is exactly the way Phoenix is doing it.

Ed


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## Greg Elmassian (Jan 3, 2008)

Ed, In a BEMF decoder, BEMF is always in play unless it has been turned off manually... 

I have seen "cruise control" used by several people, in the rest of the world it usually means a BEMF setting that causes the loco to run the same speed no matter what the load... I have no idea what Lewis is thinking of doing, but without a true tachometer on the motor (which is what MTH uses), it's impossible with electronics WITHOUT BEMF. 

I think this is getting a bit muddled. You asked several questions, and I was starting by answering your first question. 

Again, the Phoenix only senses voltage, not current... so it cannot sense load... period... there is just no way. 

Now if that part is clear and you want to talk about prototype operation, that's fine too, but I think this is getting muddled... 

Again, the Phoenix cannot sense load, nor current, only voltage applied, and in the example I gave you it should be pretty clear that the voltage in the application with the Phoenix on DC is the only "input" it has. 

You cannot say the Phoenix senses (motor) current... it does not. It's impossible. 


Regards, Greg


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## DKRickman (Mar 25, 2008)

I can't really comment on the sound systems, but there are a couple questions about the real thing I can answer. 

First off, the 8 position (technically, 10 position, since stop and idle count as well) throttle controls the voltage to the traction motors AND the governor of the prime mover. That leads to the second point, which is that the prime mover DOES vary its speed as the throttle position changes. It goes from about 400 RPM at idle to around 1000 RPM at full load. As for "cruise control," some of the newer locomotives do have a low speed (below 10 MPH) version, but there is nothing I am aware of that works above that speed. The "creeper control" is used for loading and unloading coal trains, dumping ballast, and other similar operations which require a very steady, very low speed to work well. 

Now, here's a question for the electronics gurus and electrical engineers out there. Since an ammeter is just a voltmeter wired in parallel with a resistor, together in series with a load, that tells me that it is possible to develop a voltage signal that varies with the current draw on a motor. Would it be possible to use that voltage, rather than (or in conjunction with) the applied track voltage, to control the output of a Phoenix?


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## Greg Elmassian (Jan 3, 2008)

Short answer, no. 

The Phoenix is looking for voltage... it has no input for current... you need 2 signals, voltage and current... it's just not designed for this and does not have 2 inputs... if you tried to send a voltage signal that only reflected load you could not make it work properly either. 

(Voltage would give the "speed" and current (not as accurate as BEMF) would give the load). 

By the way, to read the current on a motor up to 3 amps takes a good sized resistor, and all the motor current would have to go through it. 

Regards, Greg


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## Semper Vaporo (Jan 2, 2008)

HOW do you measure BEMF... Yes, I know how it is generated and what it is, but the power voltage is applied to the motor via two leads. That can be measured. When the motor starts to turn a Back Electro-Motive Force is generated on the SAME two leads. If you apply a volt meter you will measure the incoming voltage minus the BEMF. One voltage only. 

How do you know what the BEMF is if all you can measure is the two leads of the motor? You'd have to have some electronic component between the power source and the motor and measure the voltage on each side. I suppose the control card is measuing the voltage that is there and subtracting the voltage it thinks it is applying (assuming the control card is varying the voltage from the track). Is that it???


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## Greg Elmassian (Jan 3, 2008)

Short answer, no 

Simply put the BEMF voltage is created when the magnetic field breaks down. This happens when the voltage is removed from an inductor. In this case it happens as you cut the power to a pole of a motor, and before you energize the next. You have to have a high speed sampling system to measure this. 

BEMF is not present 100% of the time, only in this narrow window of time. Obviously this is complicated when you are pulsing the power to the motor. 

Also we are talking about the Phoenix sound card which does NOT supply the power to the motor, so again, to try to get the fundamental question answered before we go off into space, no the Phoenix card is incapable of measuring the motor BEMF because it is not sending power to the motor. 

This is in addition to the fact that it is not designed to do this anyway. 

Regards, Greg


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## eheading (Jan 5, 2008)

Greg, you missed the whole point of my original post. I fully understand that the Phoenix only looks at the voltage it is sending to the loco motors (I did inadvertently include current which was in error). I am fully aware that the Phoenix board does NOT look at any BEMF. What I really want to know is what happens in the real world, in a real locomotive. So ---- let me try again with my question.

My real question here is, what happens in the real world, not in our model trains!!! Ken, your answer was most helpful to me, in what I am trying to understand. I understand that the RPM does vary with position selection on the, what I'll call the rheostat setting on a real engine. What happens however, when the real engine reaches a grade to go up. If the "rheostat" is unchanged, the engine will slow down as the load increases. The question then is, if the "rheostat" isn't changed, does the diesel engine change speed, or does the load change on the diesel engine. My simplistic view is that the engine will only change, or see a load change, if you move the "rheostat" setting, or as an example if you move the "rheostat" from notch 5 to notch 6 or 7. Is this correct?? Or does the diesel engine sense the drop in speed and respond to that without changing the notch setting??

Another way of asking the question I guess is, in the real world, does the locomotive look at BEMF, or is it just looking at the voltage it is applying to the electric motor?? Here is where the QSI/DCC vs. Phoenix question comes into play. If the real engine is JUST looking at the voltage it is applying to the electric traction motors, then it is doing what Phoenix does. If the real engine is looking at BEMF, then it is doing what the DCC decoders are doing.

Thanks,

Ed


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## Greg Elmassian (Jan 3, 2008)

Another way of asking the question I guess is, in the real world, does the locomotive look at BEMF, or is it just looking at the voltage it is applying to the electric motor?? Here is where the QSI/DCC vs. Phoenix question comes into play. If the real engine is JUST looking at the voltage it is applying to the electric traction motors, then it is doing what Phoenix does. If the real engine is looking at BEMF, then it is doing what the DCC decoders are doing. 

The locomotive does not look at anything. 

There is no sound card in a real locomotive, so saying what you said above is not making a lot of sense to me. 

Maybe we could further refine the question. 

Is your question about sound? I think it isl. Are you trying to figure out how prototype sound is generated, and then relate it to a DCC decoder that senses load like the QSI, or the Phoenix which merely senses voltage? 

I think that is what you are trying. 

So, I believe the question should be: 
*
"in the prototype, what factors affect the changes in the sound of the locomotive, just the throttle setting, or are there multiple factors, like throttle setting and load on the locomotive?" *

I think that is what you are asking. The answer is obvious: It's throttle setting AND load. That's why these manufacturers have gone to all the trouble to do this. Manufacturers who cannot sense load do other things like watch the rate of change in the voltage to simulate deceleration and acceleration. 

Regards, Greg


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## Engineercub (Oct 18, 2008)

Is BEMF an acronym for Ballerinas Elegantly Maul Fish?









-Will


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## Semper Vaporo (Jan 2, 2008)

BEMF (Back Electro-Motive Force... Electromotive Force is the scientific name of the property that is measured in "Voltage"). 

Voltage is generated whenever a wire is moved in a magnetic field, not just when the field collapses. Back-EMF is a voltage induce in a wire that is moving in the magnetic field because a Forward current is creating a magnetic field in opposition to the stationary field and thus moving the wire out through the field. 

If the applied voltage is being pulsed and the sensing circuitry is detecting residual voltage from the motor between pulses. This voltage would be the result of the motor still turning (moving the wire through the magnetic field). I must assume the sound card is measuring the peak voltage to determine what is being applied and then seeing the lower voltage to determine what speed the motor is moving at in response to the applied (pulsed) voltage.


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## aceinspp (Jan 2, 2008)

Ed in the real world of locos its not called a rheostat its a throttle which is used to increase the diesel speed which in turns creates more amps to provide more power to the traction motors. Throttle setting go from 1 to 8. Also there is a neutral or park and you can rev up the engine just like a car and go no where. To my knowledge in to days locos there is no cruse cronrol as the engineer has to have full control of the train at all times. Later RJD


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## eheading (Jan 5, 2008)

thanks, RJ. I knew that the "rheostat" was called a throttle, but I wanted to make sure I differentiated this control from a throttle on a gas or diesel engine. Didn't know that you could rev the diesel engines in "neutral" though. That is interesting.

I'll be darned, Greg, here all this time I thought the real engines had a sound board that created the sounds emanating from it!!







Your "reinterpretation" of my question was correct.

Ed


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## SlateCreek (Jan 2, 2008)

Ok, all of you take notice: Here's the real story on how diesels work: 

http://www.sdrm.org/roster/diesel/facts_fables.html 

Hopefully that will clear up a bunch of questions for most of you! 

Matthew (OV)


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## George Schreyer (Jan 16, 2009)

Actually.... 

BEMF is there ALL the time that the motor is turning. It is the RESULT of the motor acting as a generator. The BEMF is typically about 80% of the applied equivalent DC voltage but with a reversed polarity so it bucks the applied voltage. It is also what keeps the current in the motor under control. As the motor is slowed by load, the BEMF generated is reduced resulting in a greater NET voltage across the motor, resulting in increased current in the motor resulting in increased torque and an attempt to regain operating speed. All this happens internally to the motor without the need external control. It does not result in perfect speed correction, it just corrects in the right direction. 

BEMF decoders SENSE the BEMF of the revolving motor between motor drive pulses and use this information to provide the rest of the speed correction. 

When the BEMF signal is small at low motor speeds, the decoder may actually have to drop pulses to be able to get a long enough window to detect the value of the BEMF. This can result in a "hum" in an otherwise silent running decoder as you hear the period of several lost motor pulses several hundred times a second. 

The decoder knows what the target BEMF is for any given pulse duty factor and it adjusts the duty factor to achieve that target. It knows how much it is correcting the duty factor to achieve the target so therefore it has some information about the load. When the sound system and motor driver are integrated, this information can be passed to the sound system telling it to change the prime mover sound in some way to make it sound like the locomotive is loaded (or unloaded). 

BTW, the throttle in a diesel loco is NOT a rheostat. It is a controller that sets a bank of relays in a control cabinet that change the amount of current that flows through the series wound motor fields among other things. It also causes the motors to be "rewired" from series to series parallel at some particular speed (the "transition").


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## SteveC (Jan 2, 2008)

Ed

Here's another link from the one that Matthew provided and what George just said. I'm sure that all diesels don't work this way but at least it explains the basics of a diesel/electric.

*http://www.sdrm.org/roster/diesel/diesel_fund.html*


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## eheading (Jan 5, 2008)

Thank you Matthew,George, and Steve, that is exactly the kind of information I was looking for.Matthew your reference made for very amusing reading as well as being informative. And George I did not understand that the motors were generally operated in both series, and parallel configurations depending on speed and load of the engine. Your writeup, Steve, answered a lot of the questions I had too. Thanks to all.

Ed


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## George Schreyer (Jan 16, 2009)

Normally, diesel locomotives have one transition, usually from a series connection to a series-parallel or straight parallel connection. On SOME locos, there were TWO transitions, one from series to series-parallel and then another to straight parallel, however, this was deemed more trouble than it was worth and the two transition scheme died. 

The throttle does reset the governor, but only to the extent that it kicks the diesel off idle at notch 1. I don't think that the governor was changed after that. The governor would change the fuel feed to keep the engine RPM constant depend on the load applied. 

The transition process itself would also impact the governor, the engine fuel would be cut off to some extent during the transition to prevent the engine from going overspeed as the load was relaxed during the transition. The engines would not transition at load because it was too hard on the contacts in the control cabinet and tended to result in arcing. This was a problem when trying to pull a grade at maximum horsepower. The few seconds it took could often cause the loco to slow enough to drop BELOW the transition speed and it would try to transition back right away. If that happened, the engineer didn't have much recourse except to slow down and wait it out at a speed below transition. Sometimes at reduced throttle, the train would lug and slow and he'd have to continually apply and relax power to keep the thing moving until the load reduced. If this didn't work and the speed could not be maintained above about 10 mph, the motors could overheat and the engineer would simply have to stop and wait for help. 

I need to reread the GP9 operating manual again, I think that I got most of it right

http://gelwood.railfan.net/manual/gp9-master.html


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## DKRickman (Mar 25, 2008)

Posted By George Schreyer on 04/19/2009 5:42 PM
The throttle does reset the governor, but only to the extent that it kicks the diesel off idle at notch 1. I don't think that the governor was changed after that. The governor would change the fuel feed to keep the engine RPM constant depend on the load applied. 

The transition process itself would also impact the governor, the engine fuel would be cut off to some extent during the transition to prevent the engine from going overspeed as the load was relaxed during the transition. The engines would not transition at load because it was too hard on the contacts in the control cabinet and tended to result in arcing. This was a problem when trying to pull a grade at maximum horsepower. The few seconds it took could often cause the loco to slow enough to drop BELOW the transition speed and it would try to transition back right away. If that happened, the engineer didn't have much recourse except to slow down and wait it out at a speed below transition. Sometimes at reduced throttle, the train would lug and slow and he'd have to continually apply and relax power to keep the thing moving until the load reduced. If this didn't work and the speed could not be maintained above about 10 mph, the motors could overheat and the engineer would simply have to stop and wait for help. 

I need to reread the GP9 operating manual again, I think that I got most of it right

http://gelwood.railfan.net/manual/gp9-master.html




That may be true for older equipment. The oldest thing I'm familiar with is a GP38, ca. 1965? On equipment of that vintage and newer, the engine speed does vary with throttle position. Somewhere in my training manuals I have a chart which shows (roughly) what speed correlates with what notch, but it's a more or less linear change from 400 to 1000 rpm. As for making transition, EMD locomotives will definitely make transition at full load, at roughly 25 mph. Of course, at 25 mph you're nowhere close to full load anyway, so it's not TOO bad a strain. I do not know whether a GE even makes transition, though I assume it must. If so, it's much gentler than an EMD.


As for overheating, it doesn't really have a lot to do with transition. As the traction motors turn slower, they draw more current. I've seen as high as 1500 amps (at about 600 volts) at 2-3mph. That much current heats the windings in the motors, and the motors cannot dissipate that heat fast enough. That's why locomotives have short time ratings. Once that rating has been exceeded, you have to stop and let the motors cool off, usually by revving the engine (and thus the blowers) for 10-20 minutes.


Now, how all this relates to the noise being made: As the throttle is advanced, the engine speed increases, as does the volume. This is true regardless of load, and can be heard even with the reverser centered. As the load on the traction motors increases, the engine speed remains constant (for a given throttle notch), but the volume and "bark" increases significantly. In model terms, the motor voltage would determine engine speed, while the BEMF would determine volume.


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## lownote (Jan 3, 2008)

I have a phoenix card in a USAT 44 tonner. The Phoenix sound file is the Alco SR-3. And I have an aristo Rs-3 with a QSi card, also set for Alco RS-3. 

The Phoenix sounds good but it does not change much--I set it to a given speed and it stays the same, all the time. The QSI is constantly changing as the engine encounters grades. Sometimes it's nearly silent, sometimes it's roaring and laboring. Maybe I should make a movie of the difference. The Phoenix file is a nice sounding file, but the QSI file is much less monotonous


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## eheading (Jan 5, 2008)

Kenneth, that REALLY answers the question that I had. And Lownote, it is nice to hear the one to one comparison between the two soundboards running the same engine's sound file. Thanks for both explanations. I really love that RS3 sound in the Phoenix board. I imagine it sounds even better with the QSI.

Ed


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## George Schreyer (Jan 16, 2009)

The QSI knows something about what the motor is actually doing. The Phoenix doesn't, it only knows what the motor has been told to do. 

After reading the GP9 manual again, the throttle DOES control the speed, there is about and 80 RPM increase for each notch from 275 RPM to max at about 850 RPM. 

BTW, that site has manuals for LOTS of locos, many of them operate somewhat differently. 

http://gelwood.railfan.net/manual/manual.html


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## eheading (Jan 5, 2008)

Thanks for the website reference, George. I will be spending some time there!!

Ed


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## lownote (Jan 3, 2008)

Posted By eheading on 04/19/2009 7:06 PM
Kenneth, that REALLY answers the question that I had. And Lownote, it is nice to hear the one to one comparison between the two soundboards running the same engine's sound file. Thanks for both explanations. I really love that RS3 sound in the Phoenix board. I imagine it sounds even better with the QSI.

Ed


The Phoenix RS-3 sound file is really nice--it's clattery and rough, the horn is great, the air release is great, the throttle down sounds like a big beast settling down. It just sounds like a smoky alco. The loco I have it in pulls the track cleaning car, so it runs all the time, or at least runs during some part of every session. As good as it is, though, it gets iirritating because it never changes--exactly the same start up sequence, exactly the same brake sound, exactly the same sound at every point on the track, exactly the same throttle-down. The QSI Alco Rs-3 file is more "generic"--less clattery, smoother, less distinctive. But it varies all the time--every start up is a little different, depending on how fast I'm applying the throttle and whether or not it's under load. 

My ideal would be to have the Phoenix sounds in a QSI card. The same Phoenix card used to have a PRR K4 sound file on it, which was equallly good but equally unvarying in an Aristo Pacfic--the same chuff all the tme. The Pacific now has a QSI card, and it's very different --sometimes the chuff is throaty and forceful, sometimes you can barely hear it, all depending on the load and the grade. Linking the sound to the decoder like this really makes a difference. 


It's one reason why I decided not to look at aristo's new revolution TE. It looks to be a great system in many ways, cheap and easy, but I'm sold on the way QSI manages sound. I was actually really surprised that Aristo didn't do a better job of integrating sound in their new system, and I kept posting questions over there--"is there no option for built-in sound, as with QSI?" 


IMHO the ideal system would be DCC made really simple--a software interface that does for CV values what the graphical user interface did for computers. DCC is like the old days of typing in command lines, but what we need is something like windows or the mac interface. A handheld the size of an iphone, with a touch screen and a throttle wheel


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## Greg Elmassian (Jan 3, 2008)

I waited 6 years for the large scale Tsunami from Soundtraxx, but they never made it. They have the same BEMF interaction with the sounds in their very successful HO decoder. The first time I heard this "interaction" was on a Lenz decoder with a DEITZ sound card (they use a serial interface between the 2 decoders to transmit BEMF information)... the increase in realism really impressed me and that's where I wanted to go. I have a number of grades on my layout, and the diversity of the sounds is great, it adds so much more interest. 

There are graphical interfaces Mike, try JMRI, and to a certain degree, the Quantum CV manager, the other program on the QSI cd. 

Regards, Greg


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## lownote (Jan 3, 2008)

Greg:

Always a mac/pc issue. I have the CV manager but have not tried it. I don't have USB to serial cable, etc.I want it handed to me--I'm being lazy!


What I meant is it ought to be able to possible on the fly, with the handlheld, using a screen. As Bob Grosh points out, there's so much more DC could do. Pictures of the loco, consist by dragging them together using a touch screen, set speed curves by dragging a line, etc. 

But I'd settle for a quillable whistle!



Any word on when QSI will release the updated sound files? I've been waiting and Tony said, in Decemnber, that "it would be a few more months."


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## George Schreyer (Jan 16, 2009)

JMRI works the same on a Mac, Linux or PC and it provides a graphical interface to decoder programming. Further, it is free. 

You do need to provide some form of communication interface to the DCC system. With Digitrax, the PR3 or a LocoBuffer-USB provide that interface for around $60. I'm using both with a Mac and both work. The LocoBuffer is a little easier to set up but neither are difficult.


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## lownote (Jan 3, 2008)

I just looked at JMRI, and I'm cnfused about a couple points. First, it does not seem to be compatible with QSI--is that so? QSI is not listed among their "compatible manufacturers."

Second, it says I need a serial to USB interface. But why? I have QSI Programmer, which has a usb based interface between my latop and the programming track. I asume I cna't use that because JMRI is not compatible? 


Any help much appreciated


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## Greg Elmassian (Jan 3, 2008)

Support for new decoders gets added pretty quickly, George knows this particular detail better than I. 

You need an interface to a command station, not the QSI programmer. The command station is generic DCC commands, the QSI is specific to programming the QSI it's own way. 

My NCE has a serial port, and you can also buy a USB programming interface from NCE (I have one but have not played with it yet)... 

The idea of JMRI is to have a generic program controlling the command station. I know you have AirWire, so you have a "mini" command station in your throttle. AirWire does not make an external port to the internal command station. 

Hope that clears a little confusion. 

Regards, Greg


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## George Schreyer (Jan 16, 2009)

The Phoenix and QSI programmers are stand alone devices. JRMI communicates with your command station so that it can make the command station do anything that a throttle will do, just with a much better interface while programming. Digitrax also makes a programmer for their sound stuff, BUT it also an interface to a Digitrax command station (although it can't do both at the same time). 

If you don't have a traditional DCC command station, then JMRI will do you no good at all.


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## lownote (Jan 3, 2008)

Ah! Understood--thank you


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## toddalin (Jan 4, 2008)

*Weighting Factors and Sample Emissions Data for Sample Tier 2 Locomotive*
*Notch*
*Power (bhp)*
*Fuel Use (lb/hr)*
*CO (g/hr)*
*NOx (g/hr)*
*ROG (g/hr)*
*PM10 (g/hr)*
*Percent of Time at Setting (Line-Haul Duty Cycle)*
Idle
17
20
30
329
24
7.7
38.0
Notch 1
268
102
142
1,135
62
69.3
6.5
Notch 2
587
210
239
2,730
120
145.8
6.5
Notch 3
1,187
449
607
5,310
220
304.3
5.2
Notch 4


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## bdp3wsy (Mar 14, 2008)

Greg and George, Thank you I thought I was having a problem with my QSI where the sound wasn't always constant. After putting it thru its paces again and comparing where the sound was changing makes you description perfect sense. Going upgrade with a load was louder with additional sounds and while going down hill was a much more muted sound. The braking sounds were allways changing also then I realized some where triggered by slowing down quicker and some by gradual braking. I hope Tony get the upgraded chuff sound up soon. Jake


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## SlateCreek (Jan 2, 2008)

I know this is kind of late in the game..... but probably worth mentioning.... 

My old layout had some pretty dramatic grades. I had an LGB 20550 with a Sierra sound system in it (I think it was the one for the GP-9, oddly enough... it was the first Sierra diesel sound system ever, and they installed it, and then used the loco as a demo at some shows that year.. .but I digress.) 

The Sierra was pretty carefully designed to give you 8 distinct "notches" in engine speed, and was definable as to where those notches happened (you could set it up to go through all 8 by like 9 volts, or by 18 volts.... something like that) and all things being equal, where the locomotive was, the sound stayed. 

But... 

If you were careful about what "cruising speed" you picked, you could get the system to hover on two different notches, which, if it was between notch 3 and 4, was also where the series/parallel transition was. As such, on the flat, the engine would run along in notch 3, but would then hit the grade, and by virtue of the track voltage dropping as the motor load increased, the sound system would drop down to notch 3, and the engine would actually rev up (remember, you go from a roar at full series to a much lower RPM at first parallel, almost like upshifting in a road vehicle) until it crested the hill, and then as the load on the motor backed down, the voltage on the track came back up and it'd notch back up again. Made for something a little different than the oft-heard constant droning in diesel sound systems. 

And the interesting thing is, it was an exploitation of a 'problem' with the as-is system. 

Matthew (OV)


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## eheading (Jan 5, 2008)

That is interesting, Matthew. Also from the comments from several posters, I now understand why the sound does change rather drastically going between some notches on my soundboards. This is probably where the transition takes place. Never understood that before. Learning something all the time!!

Ed


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## SlateCreek (Jan 2, 2008)

I'm realizing my typo above, but way too late to edit. That should read Cruise along in Notch 4, then drop to 3, and then notch back up to 4...


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## eheading (Jan 5, 2008)

Interesting what the brain can do, Matthew. That is exactly what I thought I read!! I guess I knew what you meant!

Ed


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## noelw (Jan 2, 2008)

Posted By Greg Elmassian on 04/18/2009 10:19 PM
Short answer, no. 

The Phoenix is looking for voltage... it has no input for current... you need 2 signals, voltage and current... it's just not designed for this and does not have 2 inputs... if you tried to send a voltage signal that only reflected load you could not make it work properly either. 

(Voltage would give the "speed" and current (not as accurate as BEMF) would give the load). 

By the way, to read the current on a motor up to 3 amps takes a good sized resistor, and all the motor current would have to go through it. 

Regards, Greg




*Like Greg said.... Voltage stays the same so the idea we use on our r.r. is we use Radio shook Wire wround resis. 10 ohm @10 watts in a bank of 4. in all of our USA diesels. We really haven't done much with Aristo craft do to we only own one RS-3 and a center cab. and they are switch Eng's. 

We put a SP/ST toggle switch to short out the Resis. bank when not needed for hill climbing or MU.

Works great on climbing a grade do to like Greg said. have to change the voltage to let the sound card know of a change. So the Resis. bank takes the Amperage draw and the voltage when raised will get another notch out of the sound card do the voltage change.. 

Just remember to mount the Resis. bank away from plastic or wires.. I mounted my over the Lead wt. And if I want to run my Eng. with some one Else's Eng. just flip the bank switch on the fuel tank back to normal run. 

My largest grade on our r.r is 2 % and its works fine after I experimented and calculated for a month on it .. Now it depends on how much of a rolling stock load to the Eng's. that i have to raise the voltage to clime the hill.
The more power (Voltage) for the hill the sound card will shift to a higher notch so sound like its really pulling the hill being that the Eng. is going slower now. 
"So what happens is now I've increased the voltage to say 15 volt but Eng is going slower up the hill do to the load on the Resistor bank." 
Works great.. 

I Checked the motor block and they seem to run cool. The motor block voltage in series with Rises. bank that comes off the cir. board.

I have been running a USA SD40-2 (Note with SD40-2 we had to use a bank of 5 resis. to work with any 2 axle unit.) GP 38-2 with a GP 9 and they all Mu together and I can watch with no rolling stock to them and see the couplers just float between them. But when like the real Eng's ...when put a 60 lb load of cars on it, They work together as one unit. Neat. 

Only thing I still have is when going down hill , the wt. of all the rolling stock want to push the Eng's . But the Eng's sound drops down so the voltage can be dropped and the Amp. draw is less. 

They will buck a little but it does that when in Direct drive. w/ motor block are in normal also. Need to tie a rock on the back of the cars going down hill. with 40 or so more cars. no brakes.. hahaha. *


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## Greg Elmassian (Jan 3, 2008)

Hi Noel! 

Really enjoyed your live presentation, and also let me convey my condolences on your family situation. 

Have you ever tried diodes in series to drop the voltage? They do not make the same heat. I know others have tried this. 

Regards, Greg


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## noelw (Jan 2, 2008)

*Hi Greg.. Tks for the condolences and on the live show.. it was fun.. and we are learning from it for more shows to do live. 
Yes on tried some Diodes .. they work fine for slowing downs on Tolley cars on end of back and forth sys.. but I couldn't get the load to vary like the real thing on my grades.. 
I could insert and voltage regulator to select a area by trigger a reed to pull in a relay to insert the Diodes to do a voltage drop i guess. That has been done on my animated conductor on an pass. car so once up to speed he stops waving at difference speed on his arm (Using Diodes for fixed voltages.) . 
But By difference grades the amperage rose and going down hill or level track it went back to average running MU with other Eng.s The Diodes make a fixed voltage drop and won't verier like a wire wound chemic Rises. and lower. Just have to fig. what the Motor can draw in it safety zone and work it like a real train.. Larger grade more power. 

I've done that in Ho with 5 and 6 units Eng's pulling 2 % grades with sound sys. and it works great. 
I even tried My first Ho torque (In the late 70ths) converter that was in a PSC P-10 eng. and that was to get power to the Eng. when needed and became a idler Eng. when MU on flat tracks with another steam eng. Course you know how patents go.. good to day and gone tomorrow on some modifcation. 

Tks again Greg for the condolences. Noel & Jane *


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## Greg Elmassian (Jan 3, 2008)

Gotcha Noel, I realized that the amperage, and thus the voltage drop would vary according to the overall load. Very interesting and creative way to address this issue. Normally the varying voltage drop is a problem in circuits, here you use it to your advantage. 

I gotta remember this one. 

Regards, Greg


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## eheading (Jan 5, 2008)

Noel, That is an elegant solution for those of us who really like the Phoenix sound. I figured out recently that you can also just crank the voltage up a little when you start up a hill, but that takes overt action on the part of the operator. Your way does it automatically. Brilliant!!

Ed


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## toddalin (Jan 4, 2008)

Posted By noelw on 04/23/2009 8:37 PM
*Yes on tried some Diodes .. they work fine for slowing downs on Tolley cars on end of back and forth sys.. but I couldn't get the load to vary like the real thing on my grades.. 
Noel & Jane *




You can put differing numbers of diodes back-to-back that are specific to the hill section (with track insulators) so that the "up-hill" journey gets more voltage (and a higher engine rev) than the down-hill journey.


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## noelw (Jan 2, 2008)

Posted By toddalin on 04/24/2009 10:52 AM
Posted By noelw on 04/23/2009 8:37 PM
*Yes on tried some Diodes .. they work fine for slowing downs on Tolley cars on end of back and forth sys.. but I couldn't get the load to vary like the real thing on my grades.. 
Noel & Jane *




You can put differing numbers of diodes back-to-back that are specific to the hill section (with track insulators) so that the "up-hill" journey gets more voltage (and a higher engine rev) than the down-hill journey.




*HI Toddalin.. Yes I forgot to mention that we do have two big diodes in series in down hill direction in that 25 foot section of the trestle before the swing bridge. 
I think they were rated at 5 amp. each. 
Swing bridge is insulated and so is it at the top of the Hillsdale Wye in that section. . This helps the guys going to fast down hill before crossing the bridge being that section is mostly curves. 
Sorry I didn't put that in due to we were talking about going up grades.. 
*


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## toddalin (Jan 4, 2008)

Posted By noelw on 04/24/2009 12:07 PM
Posted By toddalin on 04/24/2009 10:52 AM
Posted By noelw on 04/23/2009 8:37 PM
*Yes on tried some Diodes .. they work fine for slowing downs on Tolley cars on end of back and forth sys.. but I couldn't get the load to vary like the real thing on my grades.. 
Noel & Jane *




You can put differing numbers of diodes back-to-back that are specific to the hill section (with track insulators) so that the "up-hill" journey gets more voltage (and a higher engine rev) than the down-hill journey.




*HI Toddalin.. Yes I forgot to mention that we do have two big diodes in series in down hill direction in that 25 foot section of the trestle before the swing bridge. 
I think they were rated at 5 amp. each. 
Swing bridge is insulated and so is it at the top of the Hillsdale Wye in that section. . This helps the guys going to fast down hill before crossing the bridge being that section is mostly curves. 
Sorry I didn't put that in due to we were talking about going up grades.. 
*




So then, to get the engine to "rev-up" in the uphill direction, my idea is to take this one step further. Assuming that you are using track power with blocks, you can put four diodes (two head-to-tail with the two head-to-tail groups mounted in opposide directions) on just one of the power pack feeds that goes to "most" of the blocks between the power pack and the track blocks. In this way all power going out is reduced by 1.4 volts from the actual power pack setting regardless of direction. Now for the blocks that feed the upgrades where you want the engine to rev up, instead of taking your feed off the -1.4 volt feed, run that wire back to the power pack and use one diode in the uphill and two in the downhill directions. So now trains going downhill still receive the -1.4 volts, but the uphill trains receive a -0.7 volt feed for a difference of 0.7 volts. This difference will make the sound card receive more voltage and depending on the sensitivity setting, should shift up to the next rev setting, but is not so great that the trains should visibly speed up going up the grades, especially with the additional actual load created by the grade.


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## noelw (Jan 2, 2008)

Yes.... if you want the Eng's. to reb. up in both directon. We want ours to idle down going down hill and Dym. brake kick in off of Reed mag. on ours.. but, you have the right idea now.. Noel


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