Pulse wave modulation, No.

I seem to remember that if you have a regular power pack and the unit stated it can run DCC and DC you would be okay.  Follow the instructions that came with your DCC equipped unit.

Then there are the higher end power packs using pulse wave modulation that allowed for momentum and realistic creeping.  I have one.  I never tried it with a DCC equipped unit, but I read that those will not work with a DCC/DC engine.  Could be wrong.

Den

PWM

I belong to a number of train forums and I have seen that a lot. The pulses can confuse the microprocessor on the decoder.

Try it is a good suggestion to prove a theory.

Rich

PWM and DCC: Nope.

Regular DC should work OK, provided the decoder has been programmed to revert to analog (don't recall which CV it is, but I believe analog reversion is the factory default).

At a show, a friend tried to test a newly purchased DCC loco on my portable layout, which runs on PWM. It didn't work. I think that, if the decoder sees a squarish wave with steep edges, it decides it must be on DCC, but of course the PWM signal doesn't have all the right timings to look like proper 1's and 0's. I have not repeated the experiment with my own DCC engines.

Don't know much about DCC

I really don't know a lot about DCC as I am a DC only operator. My layout is built mainly for switching and being a lone operator, I rarely operate more than one train at a time, and when I do, is is usually two or more locomotives in MU for helpers up a grade.

I did run across a Bachmann Alco switcher which I did pick up equipped with DCC and sound mainly because I am a sucker for anything decorated in Milwaukee Road colors. The locomotive operates just fine on my DC layout. The only problem I have is an operator problem, keeping the throttle open enough to maintain the sound without totally shutting the unit down.

Here is a video of the unit in operation. I use a GML solid state walk around throttle with memory.

Pardon the shaky video as I was alone trying to operate the throttle, throw turnouts and keeping the camera pointed. All of the horn signals and bell are apparently pre programmed.

Dual-Mode

*Some* decoders will work on analog DC, if the decoder is a "dual-mode" decoder. (I think actually quite a number of decoders are dual mode.)

With the above caveat about PWM. (I didn't actually know that one, but makes sense.)

I have found

That it actually depends on the decoder manufacturer.  In general, the pulse coming into the decoder can and usually does cause erratic responses, sometimes it will settle out sometimes not.  Usually it is written in the decoder documentation that the pulse signal will cause a problem.  I find TCS decoders seem to be less prone to the problem.  I haven't found one that had a problem with the pulse signal, but my experience with these is limited.

My tests also show that with a pure DC signal, all of the decoders tested so far have responded properly.  This is independent of manufacturer. 

Experiment done....

....and apparently, I lied . I tried a locomotive that I haven't got around to putting my usual CVs in yet, which runs on both DCC and a regular DC throttle (MRC Tech II. My track feed is connected through a DPDT switch so I can change the whole layout over to the DC throttle for testing analog locomotives. That's why I disable analog reversion as part of my standard CV settings). So far so good.

However, it also runs on my portable layout, which has a PWM supply (a general purpose DC motor controller, which I've 'scoped and verified that it is a clean square wave). The decoder is LE062XF, which is my only Lenz decoder (the others are all Digitrax or TCS). Yes, it's a few years old; I bought the loco used at a show.

So: Lenz decoders seem to respond to PWM as a DC signal.