It depends. Most modern decoders are what are called "dual mode", meaning the decoders can sense the type of current getting to them via the rails and switch to the mode that allows them to be used safely. You would need to determine that for yourself if you have a specific engine in mind. Note that if it is also a sound decoder, it takes a bit of voltage to get the sound system to run, and then at a pre-determined lower limit of voltage, the train will begin to move. In DCC, it doesn't work that way. The rail gets the full voltage all the time, but with the digital command signal imprinted. The decoder will meter out voltage to the motor (DC current because it is a DC motor in every case) and the engine that is adjusted properly in CV2 (V-Start) should begin to move perceptibly at the first speed step dialled into the throttle. The CV that sets up the decoder to work on either voltage type is CV29. It can be set at a value of 34 to only work on DCC tracks or a value of 38 for dual mode sensing and operation.
Thanks. Reason I ask is my layout will be DC for a while, but if I pick up a loco with DCC installed, I would want to be able to use it until I convert.
Yes it can if it is dual mode capable. I have run a Tsunami equipped loco on DC but the sound starts at about 5 volts DC, the loco did not start moving until about 9 volts DC. Others have experienced about the same. If sound, a few sounds will work automaically but you have no control over the sounds. With no sound decoders, it will probably take quite a bit of turning with the control knob before the loco starts to move so do not be surprised. Also, make sure the DC controller does not have pulse power on as some decoders only want pure DC. The decoders send pulse power to the motor but has to overcome the mechanical resistance of the loco motor and gears before the loco can move. lex
Dual mode decoders, as some have already mentioned, work just fine. I have an Athearn FP45 with a Tsunami and it won't start for several clicks of the throttle but it runs just fine once you get enough voltage underneath it. I have heard several places, including this thread, that pulse power is bad. I would avoid it.
So if it takes more throttle to get them going, then I am guessing they won't lashup well with DC only locos of the same make/model?
You can't mix and consist DC and DCC locomotives on a DC or a DCC layout. You need to run one or the other, and when in DCC, you need almost always to disable BEMF (Back Electromotive Force) or the engines will tend to fight each other due to the slop in drives and in couplers.
My RS11 is DCC equipped with a dual mode decoder, but when I received it I found the DC option was switched off and I had to get a friendly DCC modeller to switch it back on for me. As Steam Donkey said, the RS11 needs some waking up before it initially runs. I have to turn to full throttle, then off, then on then off several times before it will respond. After that though it's fine and crawls along very well. It does however hesitate frequently in reverse, so I tend to avoid that. Three Atlas dual mode DCC- and sound-equipped locos have run on my DC layout with no problems at all, other than being a bit tricky to slow to a halt without shutting off altogether. No big deal though, and it can be done ok once you're used to each loco's characteristics. Mike
Correct, in many cases the DCC locos (*especially* the sound equipped ones) won't lash up with DC only locos. It's very much on a case by case basis. Sometimes you don't know for sure if your particular DC power pack / DCC decoder combination will work satisfactorily until you try it. Different DCC decoders have different 'adaptability' characteristics to different DC powerpacks. A particular case of that was the original Precision Craft Models E7s with DCC/Sound by Loksound - because of the Loksound's very nice 'engine revs up first and then the loco moves' - those wouldn't work together with the DC only PCM E7s very well at all. Furthermore, many reported (including myself), that the PCM DCC E7s would run fine on DC on some DC powerpacks, but not on others. My PCM DCC E7s wouldn't run on DC on either my MRC 9500 or my MRC Tech 200. Yet they work just fine on my NCE PowerCab DCC , and on a friend's pure DC powerpack. Go figure - something about the electronics in the MRC 9500 and MRC Tech 200. Yet on those same MRC 9500 and MRC Tech 200 DC powerpacks, the Walthers 2-8-8-2 QSI sound locos and the TCS and NCE decoder equipped locos I have, work just fine. The recent Walters Y3a 2-8-8-2s with QSI sound, definitely won't doublehead well with a DC only model - because the QSI sound has a definite 'startup lag' typical of a big real steam loco, while the DC only locos will just start up and run when you turn the throttle. On the plus experience side......I have used aftermarket TCS (Train Control Systems) DCC decoders in my (non-sound) Atlas GP7s and am delighted with them when running on a DC layout, they have worked with all three of my DC power packs, run very smoothly, and in fact act like a DC loco when they are on DC and are superb runners when on DCC - the TCS decoders are my current favorites. My NCE decoder equipped Atlas C40-8Ws also run very nicely on DC and DCC ( I think the TCS's slow speed smoothness is even better). While I've no direct experience, I was told that some older generation Digitrax decoders didn't work very well on DC. The newer ones seem to be fine, I'm told. Hope this helps. Just my 2 cents worth.
DCC decoders will run on smooth DC power. Packs that put out pulsed DC won't work until the speed is turned way up. That's because the pulses smooth out at the higher settings. Decoders respond to a unique DCC packet which is a series of pulses. Pulsed DC looks like DCC to the decoder so it just sits there unless it gets the unique pulse that will make it go. Once it sees what appears to be smooth DC, it will respond in analog mode. Usually that includes a jackrabbit start.
