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In a thread it was said that MTH engines only should run with pure sine wave waveforms. Is that true or only a marketing thing? And some of their transformers put out up to 24 VAC? Curious. So do all their transformers create "pure" sinewaves by pulse width modulation and filtering for a truer sinewave shape? Even the lesser ones than the 4000? Modern Lionel transformers are shark tooth waveforms up to 18 VAC and also 18 VDC output for Lionchief.  And then there are MPC transformers which are pure sine wave using the Variac approach like the postwar ZW and smaller postwar transformers like the 1033, etc.?

A list of all the popular transformers and their characteristics would be cool...

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There are a lot of transformers on the market today. If you include the old Lionel transformers it could be as high as 55 to 70 transformers, maybe more.

Atlas, American Flyer, K-Line, Ives, MRC, Lionel, MTH, Troller and Williams have put out transformers, at least these are the companies I know of that have put out transformers. So a list of all the transformers made would be very extensive. There could be other companies that made transformers that I am not aware of.

Lee Fritz

I think the list of QSI and early MTH engines that don't play nice with the so called "chopped" waveform might be easier, and more helpful than a list of the transformers.  

That said, all the post war transformers would be pure sine wave.  Anything with a power brick and a separate controller will be a chopped wave to some extent or other.  The Z4K is a special case, in that it outputs a more or less sine wave, though from what I've seen the output is pretty distorted... still the engines see it as a proper waveform.  

JGL

PLCProf posted:
cjack posted:

In a thread it was said that MTH engines only should run with pure sine wave waveforms.

I find no such statement on the MTH site or their literature. There is a discussion of issues with early PS-1, but apparently an engineering change was made about 20 years ago to permit proper operation with the "shark fin." See attachment. The attachment further comments that the TIU itself employs phase control which generates the "chopped wave" under discussion. It states that even the TIU caused trouble with early PS-1!

There is a statement that phase control supplies should not be used to power a TIU, only the output of a brick, See second attachment.

Let's get the facts first. Who has the MTH documentation stating that their engines require "pure sine waveforms?"

I do not believe that anyone would have information on the pure sine wave requirement.  cjack is seeking to educate me about this. I made an erroneous statement to a new guy trying to explain that he should use the Z-750 in his case. ( different issue than PS-1) I did not know about the engineering correction to late PS-1 loco's and newer MTH products.

I based that on the recommend transformer list in a TIU users guide that I downloaded from the MTH site. It still leaves out the CW-80.

So, thank you cjack and PLCProf for the knowledge.

Last edited by Moonman

A comprehensive list of transformers which lists output wave forms would be very helpful. Locomotive performance issues with different wave forms is not just a consideration with certain MTH locomotives. For example, many Pullmor motored engines with E-units behave horribly with a sharks tooth wave. They grind, rattle and vibrate loudly. I have installed a toggle switch on my layout where I can instantly switch between a Legacy Powermaster with shark's tooth output, over to a conventional postwar ZW. If I flip the toggle over to a sine wave output while a Pullmor locomotive is running along, it instantly quiets down, and runs more smoothly at the exact same speed of operation. It's like night and day. Conversely, some people might want a sharks tooth wave form to boost smoke output. It is really  an engine by engine decision for best performance.

PLCProf posted:
cjack posted:

In a thread it was said that MTH engines only should run with pure sine wave waveforms.

I find no such statement on the MTH site or their literature. There is a discussion of issues with early PS-1, but apparently an engineering change was made about 20 years ago to permit proper operation with the "shark fin." See attachment. The attachment further comments that the TIU itself employs phase control which generates the "chopped wave" under discussion. It states that even the TIU caused trouble with early PS-1!

There is a statement that phase control supplies should not be used to power a TIU, only the output of a brick, See second attachment.

Let's get the facts first. Who has the MTH documentation stating that their engines require "pure sine waveforms?"

I can personally attest to the fact that the TIU variable voltage will drive some PS/1 and/or QSI locomotives nuts.  I had to stop testing them with the TIU in circuit and just dig out my Z-4000 for those tests.

GregR posted:

A comprehensive list of transformers which lists output wave forms would be very helpful. Locomotive performance issues with different wave forms is not just a consideration with certain MTH locomotives. For example, many Pullmor motored engines with E-units behave horribly with a sharks tooth wave. They grind, rattle and vibrate loudly. I have installed a toggle switch on my layout where I can instantly switch between a Legacy Powermaster with shark's tooth output, over to a conventional postwar ZW. If I flip the toggle over to a sine wave output while a Pullmor locomotive is running along, it instantly quiets down, and runs more smoothly at the exact same speed of operation. It's like night and day. Conversely, some people might want a sharks tooth wave form to boost smoke output. It is really  an engine by engine decision for best performance.

This reminds me of Mike R's video about the smoke output and shark tooth transformers. I don't think I remember him being clear on the details. It seemed to say that the shark's tooth was advantageous regardless of how you were using the transformer and even when I thought about half throttle and the shark tooth peak, I wondered how the power supply in the smoke area was designed to make a difference.

Not enough tech info from these manufacturers especially considering all the incredible capability of the members of this forum. There is no doubt in my mind that this forum is fueling a decent percentage of the O gauge market. Their bottom lines depend on a broader base like the sets, and traditional sized product, but the activity here helps to keep the hobby alive and interesting...and relevant technologically.

gunrunnerjohn posted:

I was amazed when I put the 'scope on the CW-80, it probably explains why there are so many issues using it with stuff like PS/1.

Maybe a little gain change is all that's needed. I don't remember seeing that on any of the triac controllers I've seen over the years, and I've seen a lot of them. I wonder how they managed that

I did notice the feedback loop on the A output was a little too tight or not tight enough. The output on most of the CW-80s I have had would oscillate enough to show up on the brightness of incandescent lamps. I was using one for accessories. I had to switch to the B output.

I am not that good with transformer outputs, however I know that a Lionel CW-80 won't work with most MTH PS-2 engines. I can't say about the new MTH PS-3 engines as I have not tried one with a CW-80. I don't own a CW-80 or have access to one any more.

One thing that I have learned is that some of the Weaver engines won't work nicely with the MTH Z-1000, a Weaver C-630 I have prefers the old post war ZW.

Lee Fritz

gunrunnerjohn posted:

This may be the answer to the funny waveform.

Too funny - but not the case.  If you look closely at the bottom, you'll see I've got the chop turned on.  B channel is my function generator outputting a 60 Hz sine wave for comparison.

My 1743A apparently spent most of its life at Raytheon based upon the metal asset tag on the case top which matches the asset number behind the CNR sticker.  Left 'em all on as a part of its history.

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