I just read in a leading hobby magazine that while some DCC systems will run a DC loco that it is not a good option. Why is that not a good option. Does a DCC system ruin DC locomotives?
I have some loco's that I would not convert to DCC but would like to run them occasionally.
I am looking at DCC systems now and some systems will allow one DC loco to run while others do not. What are the pro's and cons.
Thanks for your thoughts and advice.
Dave
A DCC system puts a high frequency AC square wave signal on the track (the DCC command signal). The gimmick used by some DCC systems is to stretch one of the positive or negative pulses of the DCC signal to run a DC locomotive on address 0. This sends a series of high frequency pulses to the motor, which can cause one to make a buzzing noise and overheat if you try to run it for too long a period of time.
I think the NMRA originally wrote this into their DCC Standards and Recommended Practices only because early decoders were so expensive. With decoder prices what they are today, you're better off installing a decoder instead of running the loco on address 0 and risking damage to the motor.
Some of the MRC DC power packs have a so-called "pulse power" which basically does the same thing at slow throttle speeds to help "kick" the motor. This, too, can cause a motor to overheat if you run on pulse power for an extended period of time. Most controllers automatically change from pulse power to straight DC at higher throttle settings.
Even with decoders, motors still receive pulse power. When the loco stops, the pulses are gone.
I used an Oscilloscope to verify the pulses. The scope is a solid state Velleman HPS5.
With a DC loco using a DCC system that can run DC locos that do not have a decoder, there are pulses on the motor even though the motor is not turning. I use to use a MRC 2000 DCC controller that can run one DC only loco and I could hear the motor buzzing even though the loco was not moving. This is what is hard on a DC motor because it cannot spin and dissipate the heat.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Even though the motor is not turning the power is still going through it, therefore it sounds like an electric shaver on steroids. I did an experiment a while back with some old Athearn BB motors to see what extended exposure to DCC would do to them. Two were left on track power at throttle position zero. One burned up after about an hour while the other lasted for over six hours. A third motor was run at what would be scale speed of 50 mph for over 12 hours. While it got warm it never showed any signs of trying to burn out. Now I'm not saying that it may not hurt them. I may have unintentionally chosen a particularly tough motor for the test.
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
Heavier 3 and 5 pole motors will run fine as long as you don't let them sit non-moving for extended periods. As long as the armature is spinnign it can stay cool - sitting still teh heat just builds up until somethign melts, either one of the windings or the sodler joint between the winding and the armature, and your motor is toast.
A precision coreless motor - do not EVER set one of those on DCC track if it doesn't have a decoder. They have no armature mass to help dissipate heat and will quickly melt down. Even WITH a decoder - make sure it's a "high frequency" "silent running" "supersonic" "pick you marketing term" decoder, low frequency PWM from a cheap decoder will also burn out coreless motors. Not that many peopel ahev all that many coreless motors in their equipment.
Sometimes, that harsh DCC pulse is just what the doctor ordered. One of those old Bowser PRR T-1 models with the HUGE motor..make that huge motorS, it had 2, one for each set of drivers, would not even spin upside down on DC power. Putting it on the DCC tracks and using address 00 it actualy started moving, some continous runnign in both directions freed it up greatly, to the point where it would run on DC - but never as smoothly as on DCC. Hard to break in a mechanism if you can;t get it to move - the DCC helped greatly here.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Once when the modules were set up a club member set 00 to run his non DCC loco and my older Soundtrax decoder got fried. It was an old B280LC that was not to be run on DC at any time. Why it fried the motor circuit I dont know. All I know is it was running fine then an abrupt stop and smoke out the tender. After that all it had was lights.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
The coreless motor issue for DCC has been discussed in the Yahoo SoundTraxx group by someone using a MicroTsunami. Go read.
You should run one of your DC engines on DCC, just to try it out. I had to do that to see how it worked, since I too had a bunch of DC engines.
I was very disappointed. Compared to my DCC locomotives, the DC engines were just terrible. The DCC engines run quietly and smoothly, while the DC engines make that horrible sound, and run slowly and rough. When they get to an auto-reverse section, they short out, because DC-on-DCC does not work through auto-reversers.
Instead, I learned to isolate the motors from the frames, replace old incandescent bulbs with nice bright LEDs and install decoders myself. These are good skills to develop anyway, but the real payoff is bringing those engines up to modern standards.
Yeah, you can do it.
It takes an iron man to play with a toy iron horse.
You're gonna see lots of differences in the meaning of DCC Ready. This can mean that the loco is completely set up to have a decoder simply plugged into it or you could find it's at the other end of the scale and has simply had the motor isolated from the frame.
Don't be fooled by DCC Capable either. This simply means that the loco can be converted to DCC (by you, sometimes with a lot of work). Athearn BB is a good example of the easier to convert DCC Capable locos out there. I've seen some that are far worse.
EVERYTHING is DCC capable - however that says nothing about how much effort will be required to install a decoder. Sicne there's no real standardization of the term "DCC Ready" either, I suppose you could say everythign is DCC Ready - after all you can open it up and connect a decoder somehow.
Yes I was being somewhat sarcastic - given that the range of "DCC Ready" runs from "take off the shell, plug decoder into socket, put shell back on" to "plug in decoder, but change light bulbs" and "solder decoder wires to these numbered holes, and cut these circuit board traces"
Until you gain experience and can tell what sort of install effort is required by examining the loco, the best thing to do it look on various manufacturer and reseller sites that have install pictures. One or more probably has pictures or at least descriptive info for the loco you're working with. Pay attention to what they show and you'll soon see the WHY as well as the HOW. Once you nderstand the WHY, you can grab any loco and figure what would work in it.