Chopped vs smooth sine wave

Yes. Also can vs. Open frame Pittman style,like most Lionel loco's will also show drastic start and low speed performance differences. I believe models of all makes equipped with on- board electronics prefer a chopped a/c power source and operate at maximum performance.

There aren't that many modern AC-powered locos.  If you give an example we can be more specific.  However, chopped wave will almost always get you better slow-speed performance, more smoke output, and brighter lights. 

The downsides are more noise (you may hear a "growl" or a buzz that's absent on pure sine wave.)  Also, increased motor heating, and some factory electronics (such as early MTH) will balk or refuse to run on chopped wave power.  The best power supplies use a chopped waveform at lower voltages and smooth out to a pure sine wave as you increase to full throttle.

Pittman's are DC motors.  So the power coming from the transformer has to go through a rectifier and probably an electronic e-unit before it gets to them.  Whether or not you see a difference with chopped wave depends on how much filtering goes on between the power supply and the motor.

Personally I would pick the ZW-L over either of the MTH transformers that you mentioned.  The ZW-L is chopped wave, and IMO it runs postwar-style AC motored trains better than the original ZW!

@Ron464nyc posted:

Yes. Also can vs. Open frame Pittman style,like most Lionel loco's will also show drastic start and low speed performance differences. I believe models of all makes equipped with on- board electronics prefer a chopped a/c power source and operate at maximum performance.

Open frame Pittman style?  All the Pittman motors I've ever seen in model trains are can motors.

Since all electronics require DC, that means that any form of AC, pure or chopped, would have to be rectified. Hard to understand why some electronics might prefer a chopped vs pure waveform.

Well, all electronics doesn't require DC, that's probably why.

Anything that is using triacs to control voltage is using AC.  Also, if you're running in conventional mode with track power in a smoke resistor, the sawtooth waveform having a peak voltage the same as the full-wave full-throttle waveform means that you'll get better smoke performance at lower throttle settings than with a pure sine wave transformer.  The same goes for light bulbs, and especially LED's.

I was helping my own cause last night by watching this.

I asked the question because I had an MTH engine that performed as expected on the Z750 and Z4000 but my Atlas engine did not work using the Z750 on the bench but did with the Z4000 on the layout.

Threads like this always confuse me.  I run TMCC locos and PS2 locos conventionally. I also run MPC steam with AC motors and postwar steam. On occasion I even run very early prewar.  What would be my best option for a transformer ?  Do I want chopped or smooth sine wave ?  Cost is not a factor. I currently Use two Z1000s and an original ZW with in line fuses and tvs protection, but I move things around and I always wonder if one power source is better for certain locomotives than another. It would be nice if there were one transformer that would produce optimal performance from all eras.

@Ron045 which Atlas loco are you referring to?

@Keith k here's my take.  PS2: doesn't matter, runs good on everything.  MPC with AC motors and postwar steam:  runs slower and smokes better on chopped wave (ZW-L), but expect to hear a little buzz or growl.  If that bothers you, then stick with the original ZW.

My experience is that early TMCC and Odyssey locos run best under Legacy.  I don't think they run well in conventional mode at all.  If cost is not a factor, get a Legacy base and a CAB-2.  You only need one Legacy base.  This would also pair well with a ZW-L.  You can leave it installed all the time; your PS2 and conventional locos will ignore the signal and it won't affect their operation.

The Z1000 is a decent small transformer.  I'm not personally a fan of the Z4000, for a couple of reasons.  Original ZW, or ZW-L.

AC motor engines operate better on sine wave (postwar and early MPC) transformers. Using chopped wave heats the motors significantly from the brushes and growl. DC powered engines work better with modern transformers.

I have absolutely no issues running a wide variety of locomotives on modern pure sine wave transformers.  Also, when you're running command at full throttle, the issue of chopped/pure sine waves is moot, there is no measurable difference in any performance vector because the waveforms converge at full throttle.  I use the Lionel PowerHouse 180 bricks, and we use them in our modular club as well.

Thanks for the responses on my transformer questions and Ron035 thanks for posting That informative YouTube video from Mike. It helped explain everything in layman’s terms.  Ya gotta love this forum !

@Ron045 posted:

I was helping my own cause last night by watching this.

I asked the question because I had an MTH engine that performed as expected on the Z750 and Z4000 but my Atlas engine did not work using the Z750 on the bench but did with the Z4000 on the layout.

Ron,

Thanks for posting this link as I found it to be very informative as it help to answer some questions I had lingering.