Rick,
Forgot to mention that one motor of the two motor version runs in reverse depending on the direction. So when you wire the decoder make sure the motor leads are connected properly.

Al Babinsky


Sent from XFINITY Connect Application

Rick,
The Spectrum 44 ton dual motor do not run well and have not much pulling power. The single motor Bachmann 44 ton is much better and comes decoder equipped. I have installed a ESU sound decoder in the one I have. By the way ESU is the only one the has the proper sound. The 44 ton had two Caterpillar diesels and you can hear both start as power is applied. There are small speakers available to fit. This unit can pull 6 properly weighted freighters which is pretty good for a small switcher.

Al Babinsky


Sent from XFINITY Connect Application

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Rick, It is no problem to add sound. A lok sound micro or other brand of small decoder with the motors wired in series and a keep alive the loco will run great and sound great. With out a keep alive the two motor Bachman 44 tonners do not run well.

??? ??? ??? Rick.

On 7/31/2018 4:46 PM, jfm2830 wrote:

The original dual motor 44Ts didn't come with a decoder.? So if this is the version you have, a decoder would have been installed by a previous owner and no telling what he installed.? The current single motor version comes with a Bachmann decoder.

I popped the shell and it is a Digitrax DZ123. I'll probably want to replace it with a sound decoder. Space appears to be at a premium for putting a speaker in there. I suppose it's off topic to ask here about doing that so I'll check some other groups.

--

Rick Jones

No one ever says, "It's only a game" when their team is winning.

Daniel,

If you always have the PR3 plugged into the SAME physical USB port on your computer, without changing ANY of the USB "hub" devices you may be using, then the operating system will likely keep the "COM port number".

But as soon as you move the PR3 USB cable to another USB port, or add a USB hub between the PR3 and the host computer, or change how the USB hub devices is connected, the computer's operating system will likely assign a new "COM port number".

Chances are VERY good that you have connected the PR3 in a way that is different than when it was previously connected, and the operating system has chosen a different "COM port number" as a result.

On "Microsoft Windows"-based operating systems, the typical way to identify this is by using the Microsoft "Device Manager". Open that tool, then plug in the PR3 and watch the display change. You might have to "refresh" the display, and you might have to "expand" the tree of devices so that it will display "Ports (COM & LPT)" or some similar category. Once you find the PR3, note its "COM" port. Then change your JMRI "configuration profile" to match the COM port number you found.

There are ways to do this same sort of thing with Apple and Linux operating systems. If you have one of these, let us know, and someone with apporpriate info will likely reply.

Regards,
Billybob

Two suggestions:

First, make sure you've plugged the PR3 into the same USB port that it was plugged into when it worked;

Second if the above doesn't help (assuming you're using Windows), reinstall the Digitrax supplied driver for you version of Windows, using the appropriate Digitrax-supplied installation instructions.

HTH,
Steve
"Breezlys"

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Dan,

? ? Possible update on your computer.? May have lost the settings.? Have you tried a different com port?

Roger

Hello can somebody help me with my pr3 please. Jmri tells me I have no connection. My pr3 has a usb light on, (green)but status light is off. Which means no data . Tried spare cable no luck. I previously had this on com port 4, now it’s not showing com port 4. Any ideas?
Sent from my iPhone Dan

Thanks James.
I would love to visit NMRA. Unfortunately Kansas is several thousands of miles away from me here in the UK, and unlike Dorothy,? I don't have a pair of sparkly red? shoes to click heels together ;)? I've never considered CMRI, I will have to find out more. Good luck with your clinic!
Cheers

Steve

Thanks Cliff.

I seem to have lost my reply in the ether. I will try as you suggest and see if I can track down what's happening. The strange behaviour seems to be unrelated to DCC++ as it can be demonstrated within JMRI.? Turntables are created in the same way as crossover turnouts, but for each turnout, once thrown it can't be closed. It's doing something as the icon changes but the status of each turnout in the turnout table stays the same, irrespective of the turntable position.

DCC++ is just a DCC system built around the Arduino "Uno" or "Mega" Microcontroller. It's entry level digital electronics for the hobbyist and works like Lego. You build up your project by adding module 'bricks' on top of each other. It's really cheap and the GNU 'free' software is very good (you don't need to know how it works)? Because Arduino is a popular platform there are many OEM / unbranded? Arduinos out there and tons of support, so? for around $10 you're up and running. As only a fraction of the hardware is needed for DCC, the {brilliant} author , Gregg E. Berman has included the facility to use the 60 or so unused pins on the Arduino Mega and around 12 pins of the "Uno" as inputs for sensors and switches or outputs for turnouts or lighting. So in effect it is also a 60+ channel stationary decoder. JMRI includes facility to allocate DCC addresses to these pins. they are only signal level so they will need some sort of driver or relay? to control anything more than an LED.? There's no CVs they are just on or off. Of course, the DCC++ controller can send track signals to conventional decoders too. I've never used a conventional DCC system so it's difficult for me to compare. It works for me.
Cheers Steve??

Love too Dave, sent over the details. If I can I will.?

I recently presented at the Modelling NSW 35 convention 2018 and would like to attend more (as an attendee).?

Cheers,

Dave In Brisbane, Australia

Hi. Thanks for the heads up.
I'm still near the bottom of the learning curve and I think I need to grasp some more basic principles before getting into logix. I may revert to the non-DCC layout panel? turntable and place internal sensors on the ray points and? sort it out using routes.? I would be interested to know what you mean by '..,change of state'? rather than the 'turnout getting thrown'. How does the instruction to change state get onto the DCC bus? a CV code change?? If I can work out how to 'import ' the XML file I'll give the Turntable hack a try as you suggest.
Many Thanks.?

The original dual motor 44Ts didn't come with a decoder.? So if this is the version you have, a decoder would have been installed by a previous owner and no telling what he installed.? The current single motor version comes with a Bachmann decoder.

Good Luck,
John Moonan

Jon,
I think it has more to do with the low inductance of the core less design. They can saturate before the current reverses, and at low RPM there is not enough BEMF to oppose the drive voltage. I.e. high current peaks and smoked coils. I believe they will have the same trouble if they get stalled by binding drives or jammed side rods.

Don't take my tweak of Bruce's explanation as meaning that I think using stretched zero to drive DC motors is a good thing. It is not for several reasons.

Dick :)

Group:

Sorry oopsies... wrong thread... but since I see the same names I won't repost...

Jim Albanowski

Group:

This is getting to be fun...

To answer Dave... Measuring DC voltage between the ESU CC track connection and it's "ground"...

6.9 VDC each leg lad... er, other pond... mate...

I don't have the correct DIN plug to look at just what's on the ECosLink.

Fun part... It's easy to forget just what changes to voltages and signals are taking place at different places in the DCC power scheme...

Except for input power it's a pulse width scheme data or motor power but two flavors AC for data/track and DC for the motor and lights.

Assuming that my idea of using the ECoSLink to LocoNet widget is valid I'll stick to that... not sticking a wire anyplace it's not meant to go <VNG>...

Jim Albanowski

The car analogy only goes so far.

I did some work the effect of DCC pulse stretching back in 2004 or so, including making some measurements. I suspect not much has changed.

A motor under PWM from a DCC decoder is getting alternating positive and zero current. At zero speed, it’s all zero current; at top speed, it’s all positive current. In between, the pulses generate alternating positive and zero torque. (Except for some very old decoders, e.g. for decoders from after about 2002) this happens so fast that the motor rotational speed doesn’t significantly change between those two. The mechanical inertia completely averages it out.

A motor that’s using DCC pulse stretching is getting alternating positive and negative current. At zero speed, it’s positive and negative alternating at 50% time. At top speed, it’s almost al of one or other other. The DCC bit pattern isn’t slower, so there can be a small build-up of rotational speed with DCC pulse, but it’s not very much; in the 2004 measurements I saw motions of 0.002-0.003” at the outer diameter of some HO motors from Atlas and Athearn, nothing that would hurt anything or even be audible.

So what’s the difference?

1) Note that the DCC pulse stretching has a _thermal_, not mechanical, load on the motor: It’s always generating heat as if it was at full power. Maybe this is OK, maybe not. That depends on the size of motor, ability to dump heat, etc. I’ve seen G scale locomotives with motor fans that might be in trouble because they’re at full current but their fans aren’t turning.

2) To add to (1), the DCC pulse-stretching current can be significantly higher at _zero_ speed because the motor isn’t turning, hence not generating back EMF. (Not a problem for full speed running under either DC or DCC pulse stretching). Normally, as a motor runs faster, it’s generator-effect generates voltage that cancels part of the drive voltage, which in turn reduces the current. People with Tortoise stall motors and LEDs in series circuit actually use this: While the Tortoise is moving, the motor is turning fast enough to reduce the current and LED is off/dim; once it stalls, the current goes up and the LED brightens. Many small, high-speed motors rely on this effect strongly, which might be why there’s lore about “small coreless motors” have trouble with DCC pulse stretching: They’re at full stall current all that time.

One of the four motors I was experimenting with (not in locomotives at the time) burned out; one would run too hot to touch, and two were just hot.

3) There’s an increase in magnetic stress on the windings, because the change in current is a factor of 2 more (from +V to -V instead of +V to 0). The energy goes as the current squared, so this is a bigger issue in the coreless motor case, where there’s extra current.

It’s that last point that causes the whine that some people can hear. (Even back then, I couldn’t, but my kids could) The stress on the windings, or perhaps the stress on the core, can cause enough motion to be audible. The difference between this and the torque effect is detectible: The back-and-forth of the torque is at the drive frequency with only odd harmonics, but the magnetic stress sound is at twice that with lots of even harmonics

The test motor that burned out had a significant magnetic vibration; it’s coil might have been wound just a bit loose, and resulting mechanical motion dumped heat into it until the insulation melted. The one that ran hot also had a radial vibration (that’s the one my kids could hear; they weren’t present before the 1st one failed) of about 0.008”, which is a lot for such a small motor. The other two had no detectable vibration or sound.

It’s possible that older, heavier, iron core motors would be fine with all this. It’s certain that some others were not.

The reason I was looking at this back then was to understand its effect on track occupancy detection, which is a _nightmare_. An Athearn locomotive moving at about 1/3 speed threw enough HF (harmonic) current into my layout of the time to trigger about half a dozen occupancy detectors in other sections. (Decoders do a better job of keeping the very high frequencies off the rails). Basically, it became a little radio modulator. My wiring wasn’t perfect, but it wasn’t bad, and I wasn’t going to redo it.

Bottom line: DCC pulse-stretching was just another of the many Bad Ideas that tossed the NMRA into the pot when DCC was young. Mostly, we’ve gotten past them now.

Bob

--
Bob Jacobsen
rgj1927@...