The Digitrax Empire Builder II manual shows how to program a DC (analog-no decoder) loco to run on DCC with a 00 address. The DH121 decoders provide for automatic conversion to allow an analog loco to run on DCC. I have also read articles regarding consisting mixes of analog and DCC locos.
I have successfully run a Spectrum 2-8-0 with a DH121 installed on DC and a Spectrum 2-8-0 without a decoder on DCC, on a trial basis, in both cases for rather short times.
However our LHS, an authorized Digitrax distributor, strongly recommends against running any valued DCC locos on DC power or DC locos on DCC. He has had a customer who badly fried the motor in a new Proto 2-8-8-2 without decoder on DCC, seemingly after only a few minutes running. He is not confident that all decoders tolerated DC power even though advertised to do so. He also recommends changing lights from 12 volts to 1.5 volts with a voltage dropping resistor for DCC operations.
As our club is currently gearing up to install DCC in addition to DC for alternate DCC and DC operating sessions, we’re going to be very cautious and respect our LHS’s opinion, however we’d like to hear about others’ experiences.
I haven’t had any problems with any of my decoders runnign on DC power, nor have I experienced any melting of the motors in any locos running on DCC without a decoder. The noise ranges from annotying to unbearable, at least at low speeds, but after a half hour of continuous running, the non-decoder loco motor wasn;t even warm. Now, if you leave it sit idle and not moving - then it will ehat up. And if it’s a coreless motor found in some top end models (usually brass, I know of no stock plastic locos that have them), they will definitely be damaged - but they can be damaged with a decoder if that decoder doesn’t do high-frequency PWM (low end and older decoders).
The only DCC decoders I know that definitely cannot handle DC are Soundtraxx. They specifically warn you not to use them on DC. The forthcoming Tsumani from Soundtraxx WILL work on both, like the QSI decoders in BLI locos.
Bottom line - it’s not goign to hurt anythign either way, in general. I’m not sure where the idea that a DCC decoder cannot tolerate DC comes from, the on-board processor simply closes both legs of the H bridge motor drive when the DCC signal is not detected, allowing the DC power to pass directly to the motor. Running DC locos on DCC is more a nuisance than a danger tot he motor, although in a large club situation with a lot of DCC locos running, there will likely be a noticeable lag in response when an analog DC loco is running, because of the stretching out of the 0 bit, this causes it to take longer to transmit a packet, thus slower response times.
I’ve regularly ran an Atlas GP-40 without a decoder on my clubs layout that is DCC. There is a very slight hum but thats it. It ran for over 4 hours straight recently at our show with no problems. I think its an old wives tale if you ask me, lol.
Running a DCC locomotive on DC is not likely to cause problems - but there is a potential for problems, depending on the specific design of the output circuit of the decoder.
Running a DC locomotive on DCC is not bad, the bad thing is running slowly, or worse yet leaving it stopped.
one of my clubs members regularly runs some loco’s on dcc but he does not leave them on the rails when he is not running them. he uses a siding with a toggle switch to shut off the power. my club is also getting ready to install dcc. we have three tracks and we are going to leave one track for reg dc with the other two and the two yards set for dcc. we are also going to use the same dcc unit to power the separate n scale layout that we have.
My AMTRAK engine has a dual-mode decoder in it. I have run countless hundreds of hours at the mall with no problems. Also I have run a few DC engines on my zephyr at home, not very long though, that squeal gets annouying and i switch out for a decoder-equipped loco.
The noise is really an issue. I have a lot of friends that have non DCC trains and they buzz on my DCC track. Some are really loud, others just buzz. I still keep 1 track DC so they can run and run quiet.