DCC address 0, strange noise

That significant humming noise that emanates from the loco, even when the throttle is set to zero, is more or less normal. I no longer use the "zero stretch" feature but I have in the past. I never burned or overheated a motor, although there are numerous urban legends to that effect. You did not ask, but I will advise you anyway. Go ahead and buy a decoder for each of your locomotives as fast as you can afford to so do. when you have three or more locos running and are using zero stretching, you are begging for problems. Sooner or later you will find them.

........F>

Not exactly correct, but mostly correct. Many brass steam engines (and some diesel) used coreless motors at one time and some may still use them. With plastic you can be assured that off the shelf engines will not have them.

Jon,

Your comment again brings into need an answer already asked about how to tell if your engine has a coreless motor. Is there a way to tell by looking?

Bob

Not exactly correct. It's not an issue of quality, it's an issue of design. Coreless instrument motors are, by nature, delicate and sensitive. They are usually not a very good choice for model railroad applications in a broad, general sense of the word. Serious and skilled modelers who understand the workings and limitations of coreless motors will typically do well with them, but they are not for the great rank-and-file of model railroad hobbyists. Permag, skewed armature can motors are not of lesser quality, they are a completely different philosophy of design. Many of them are superbly engineered and exquisitely constructed. They are of the highest quality. To intimate otherwise is like saying that a Mercedes-Benz automobile is of higher quality than a Peterbuilt tractor. You don't want to go to the opera in a Peterbuilt, but you can't pull a 48,000 pound trailer with a 500 E. Its a matter of preferrence and need. Coreless motors were never meant to be operated on dirty, PWM DC. Permag cans don't care.

Anyway, the only way I know to be able to tell if you have a coreless motor is to already know what they look like and which companies make them.

...........F>

I would really like to see the details concerning this. What DCC system? What settings (voltage)? What kind of motor? Did it happen to you personally or to a FOAF (a friend of a friend)? I have asked for details of failure on the Digitrax list several times and no one has been able to confirm a failure, except for one guy with a coreless motor.

I have a Digitrax system and I have tested a number of locomotives using the zero address. I used both the 'N' voltage setting and the 'HO' voltage setting. I tested expensive locos (Katos and Stewarts) and cheap train set locos. I measured the motor temperatures with thermocouples in each case, and only slight rises in temperature occured after very long exposure times. In each case, the temperature was lower than the normal operating temperature of a locomotive pulling a train using a regular power pack. By the way, the temperature reaches its maximum after about one hour; it does not continually increase with time.

No one should worry about this; I certainly don't. I run locos in analog mode on my DCC system, and let them sit buzzing, all the time with no problem.

Maybe you had a coreless motor.

Paul Welsh

The strange noise is in fact the result of puttin AC on the motor. Address 0 is in fact AC. The speed control is "effectively" done by surpressing on sideband, thus decreasing one half of the waveform.

Is this bad for a motor? Conventional thinking is that applying AC to a DC permag motor will weaken the permanent magnetic field. This in turn will cause the motor to be less efficient which results in a temperature rise.

The real question is how much does it harm the magnetic field? Are todays magnets so much better than the older magnets that the effect is negligable?

To test this you need a gausemeter and do tests on like motors before and after exposure to address 0 for measured periods of time. Then you need to measure the motors efficiency.

John Glaab NASA Electrical Engineer (ret.)

mode on my DCC system, and let them sit buzzing, all the time with no problem.< I agree with all this except that only one analog engine can be run at a time with stretched zero so why would any more that one* engine be active (buzzing) at any one time. *four unit analog lashup excepted Decoders are cheap now ($15 from many manufactures) so I see no reason that all "normally used" locos wouldn't have decoders. There are also conditions during shut down (or maybe power up) where DC _might_ be on the rails causing any loco whose decoder is set for analog to runaway!

I would be less worried about heat and more worried about the long term effect on the magnets in the motor. Remember most "demagnetizers" are simply an alternating magnetic field in which items are placed. The magnetic field of the motor will grow weaker and so will its power. Do you have any way to measure magnet strength?

In my book if something is buzzing and it isn't designed too, it cannot be a good thing.

You may very well have a point. But the magnetic field strength is proportional to the current and the current is quite low; that's why there isn't a lot of heating.

No, but I would like to test this. Any suggestions on easy ways to measure magnet strength?

But it may not be a bad thing. I placed my fingers on the armature of a couple of open frame motors and could not feel any motion. I'm guessing the buzz is from flexing of the windings, similar to the buzzing of a transformer.

Paul Welsh

They are not all on the layout at the same time, of course. You are right that it's only practical to have one analog loco active at a time (even though that loco may consist of 4 units). I run different ones at different times and each may sit buzzing for hours when it's on the layout.

All of my "normally used" locos have decoders. It's the "not-normally used" ones that don't. I am blessed with owning more locos than I can use at one time. I'm only installing Soundtraxx decoders and they cost more than $15 and take a bit more work to install than a basic cheapo. In the mean time I can still run my analog locos.

Paul Welsh

No, I've puzzled it for a while and come up with things like declination on a compass or pendulums, all highly inaccurate. I posted the original note thinking that some clever person in .rec land would have some ideas.