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While collecting things for my future layout.

For conventional Transformer control .If I was going for command control I would use power supplies

I am looking into power ,more is always better 

Would Two Kw's  be better than One Zw

The specs say so  ?

Kw is 180 with two track power 90 watts each

Zw  275  275 watt  with 68 watts each with four track power

Have a train show coming up this weekend and one of the vendors there I know told me he has both 

Thanks - JW

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I think it is largely a matter of preference. Most people will tell you they are both good transformers.

While I understand what you are looking at with your math, the transformers really do not work that way. There is only one physical transformer inside either one. So whatever channel needs the power gets it.

Most folks do not use a ZW for more than two trains. The "B" and "C" controls lack a direction/whistle control. I use mine for switch machine power and uncoupling track power.

I prefer the ZW because I do not care for the controls on the KW.
Specifically, on the KW you have one control for the whistle, that is shared by both "channels". So you cannot blow the whistle on both at once. I also find that the pot metal control shaft is failure prone.

Whatever you decide to get, I suggest adding external circuit protection. Circuit breakers for postwar trains, and TVS if you are going to run anything with electronics, including electronic horns / whistles.

My suggestion: Try out the controls, and picture yourself using them. Get the one(s) you like better,


Meter Man,

   Actually no, there is more to the original ZW Transformers than just power, you must look at the ZW with 4 running Channels with 2 outside Control Handles and 2 inside control handles verses the KW with only 2 train running Handles and Channels and it's non changeable locked in accessory out puts.  This means with each individual ZW you get 4 adjustable voltage train running Channels, that can also be used for accessories.  

The ZW-L is nice but you can purchase 4 original type 250 or 275 ZW Transformers for even less cost than one ZW-L.  IMO you would be much better off monetarily, purchasing 2 completely restored and upgraded 275 ZW's from Jim Lawson right here on the OGR Forum, he restores them better than brand spanking new.


Last edited by Pine Creek Railroad

I have or have had all of the various PW transformers. The ZW and KW fall into the "wanted one as a kid" category, so I have them but don't use them! I agree with a previous poster, I do not like the controls on the KW, and the fixed accessory voltages of 6 and 20 are hard to use. The ZW is OK I guess, but they don't thrill me the way they did on 1962! The minimum starting voltage on both the ZW and KW is too high for Williams locomotives, in my opinion.

I use a pair of 1033s, at 90 watts each they total up to just about the same as a KW. Three of them would have the same power as a ZW. I like the fact that I can set them for 0 - 11 volts for use with Williams locomotives and quickly change them to 5 - 16 for use with Lionel. I also like the 11 volt accessory supply for use with many of the vibrotor accessories, it seems just about right for the sawmill and news stand as well as being easy on lamps in lighted accessories. Of course, the 16 volt accessory output is also available should you need it. 

Suit yourself, you certainly won't go wrong with either a ZW or KW. My advice is to get an inexpensive one to play with to see if you like it.


   The best way to run conventional Williams & Lionel Trains now is thru the DCS TR mode, especially the TR  Z4K mode that give smooth slow speed control to the conventional engines, via the DCS hand held remote control.  A way cool way to run conventional engines now.  Remember the old Williams Engines still start in FWD when upping the voltage with the DCS thumb wheel.  You must own both a DCS & Z4K with a side receiver to operate in this manner.   With just the ZW and the DCS you can use the TR TIU mode however.


Last edited by Pine Creek Railroad

The KW has 190 watts, two control handles and one whistle control that controls both whistle outputs. Also the KW has three accessory voltage outputs, something the post war ZW don't have. 

The post war ZW works fine with some updated parts put in it. This ZW has four track output voltages and only two whistle controls. 

Personally I would buy two KW's and get a lot more power for my layout.

The new ZW-C and ZW-L will cost a heap more money(somewhere around $700.00 new, maybe more) and may breakdown on you. I have read on both OGR and CTT forums about the ZW-C have cross voltage output from another terminal(A sends voltage to D terminal, an internal electrical issue) and also the handles fall off when being used.

Lee Fritz

Last edited by phillyreading

If you set 'em up properly there is nothing wrong with the Post War Z"-Dub.  I've been using one for about a year with both DCS and Legacy without a hitch.  I also have a MTH Z-4000 for a back-up only because I got a Heck Of A Deal on it.  Yeah, I like the digital meters but there will ALWAYS be as place for a "Z"-Dub on just about any layout for one reason or another.  Just Sayin'.

Chief Bob (Retired)

Marty F,

   I definitely agree with you, as long as you are purchasing the ZW-L for him.  


The TR Z4K and the TR TIU mode are different technology, that is why I wrote the post as I did.  The power master is probably the best, but you need a TMCC/Legacy cab1 or cab2 to operate, of course if you have both DCS & Legacy you can operate Conventionally in either manner.


I think most everyone has given reasonable advice so far but, as usual, have some things to add, and to ask.  I'm going to assume for the purpose of the discussion we are talking about a strictly conventional layout, and as such not consider what may or may not be true for TMCC/Legacy/DCS.  

I'm also, mostly, going to skip over cosmetic and operational things like the whistle control and accessory outputs, focusing instead only on their use to power your track.  I do prefer the ZW both cosmetically and for the double whistle controls, but that is more a matter of preference.  If the cosmetics and feel of the handles is important to you, give them each a try and see what you like better.  

As to which is a better choice between a KW and ZW for supplying raw power, it really depends how you plan to use them.  Both transformers have shared output, meaning any one of the outputs can deliver the full wattage the transformer is rated for, assuming you are only using that one output.  (( I'm also going to note that post war transformers are rated on input wattage, not output, so what they actually put to the track is somewhat less.  When I say rated wattage, I mean it only to simplify things.))  When you do the basic math, if you had, say, 6 tracks you are powering, 2 ZW's or 3 KW's would provide (almost) the same power, using 3 of the throttles on each ZW.  If you used all four throttles to run trains on a ZW you would have less power available per track, though this is still not a problem if you are not running trains with high draws of power.  

It seems a 10 amp circuit per track has become common place for layouts these days, but that is beyond what a KW can provide even if  used to power only one track.  I would compare a KW to the older 135 watt(7.5 amp) powerhouses and the ZW to the 180 Watt(10 amp) ones as far as how much total power they can supply.   With this comparison we can see that the KW will provide little more than 3 amps per track assuming both are equally loaded.  If using only the two main throttles on the ZW you'll get something over 5 amps on each track which is plenty for all but the most power-hungry trains.  

If all of that is too confusing, the basic rundown is, for running modern engines and non-lit/LED lit cars, neither the KW or ZW will break a sweat even using all 4 outputs on a ZW.  if you are running post war engines and/or several cars with light bulbs, the amps will add up quickly.  In that case a KW is barely enough to power one track/train, where as the ZW will probably be enough to power 2 trains/tracks.

My recommendation?   If you are running post war and lit cars, it doesn't make much difference if you choose 1 ZW or 2 KW's for every two tracks you plan on powering.  Do your math based on the cost of 1 ZW versus 2 KW's.   If you have a VERY high power demanding train, a single ZW will be the only way to go to match the power offered by a modern PH180 brick.  

If you are running newer trains with less demand for power, the choice moves more into the cosmetic differences and your preference for large throttle handles.  

I find that at  many of the shows I've visited you can buy 3 KW's for the price of 1 ZW, and leaves them a more cost effective solution almost all of the time, however I dislike the controls of the KW and am willing to pay more for the ZW

I apologize If this was confusing to read, My brain is wandering about at the moment.



Having both KW and ZW transformers, I would give the nod to the ZW, it does give you a lot more flexibility. Though people say that the ZW controls 4 channels, it was really designed to control 2 trains, the other two variable outputs (the sleeves) were designed for accessory output. They can control a train, but they don't have the whistle and direction control I believe (I never used the outer sleeves to try controlling a train). I also personally think the ZW is more durable, with the KW the whistle controller is kind of dodgy (the shaft on it is weak, plus the plastic lever can strip easily) and the train control handles are not necessarily that great from what I recall.


One of the things to keep in mind is that with the older transformers, the rated power is not what you get at the track, I believe in the day they measured it on the input side, and that does not represent what is actually available at the track (doing it the way they did was marketing, saying a transformer had 275 watts of power or 190 sounds better than prob 225 or 140, which is what they might give out at the track (I forget the actual ratio of stated to actual)). 

If you do decide to use a postwar transformer like the kW or zw, I agree with others, make sure to have a good circuit breaker on the output and put tvs across the track output as well to prevent surges if you are running any modern engines with sound systems and such. One of the advantages of a modern transformer like the ZW-L or the Z4000 from MTH is they have such protection built in. 




To the OP, are you sorry you asked yet? LOL

I will add my $.02. I have been asked this question before and the first thing I ask back is what do you intend to run? If newer stuff is the answer (command and DC motors) the easiest thing to do is buy a modern transformer and be done with it. Lionel or MTH, doesn’t matter but the newer transformers have the required circuit protection for the newer engines built in which makes things safer and easier. And bigger is better for the inevitable expansion.
If you intend to run a mix, I prefer an older transformer. Some may disagree but IMHO the ZW is the standard. But to safely run newer stuff with the older transformer, circuit protection is a must (fuses or circuit breakers and TVS’s).
All old stuff (prior to electronics) and the ZW is still the answer. IMHO, older 3 poll motors perform better with the older transformers. I believe this has to do with the newer transformers having “modified” sine wave outputs.
Of course, there are grey areas as well. My oldest TMCC loco (which I consider to be new stuff) has 3 poll motors so it is both modern and old school. It runs best on the old ZW but absolutely needs the circuit protection.
ZW or 2 KWs? Again it depends. If you are running old school conventional and want the very best possible speed control, 2 KW’s. As others have pointed out, whether it is a KW or ZW, there is only 1 transformer in there, just multiple power taps. And the power delivered to one output will affect the power delivered to another output on the same transformer. However, 2 transformers are less efficient than 1 so while it may not be much, you will waste more electric powering 2 transformers vs just 1.

For reference, I have a ‘60s ZW, a ‘50s RW, a Post War Celebration ZW (1999 or 2000 vintage with 135W power bricks) and an MTH Z-500 to power my TIU.  I also use an 11A Astron DC power supply for 14 volt accessory power where AC is not required (the bulbs last longer).

Was that $.02 or a nickels worth of free advice? :-)


Last edited by Tony_V


Thanks to everyone for all the great info .

This is what planning is all about.I want to have enough power and have room for more down the road

I have  one Kw and several Cw -80 for accessorizes and switches, etc  

A new Zw -l would be cool ,but the boss would not let me send that much ,and I am concerned over the its life time something would go wrong and would be a head ache to repair 

I will be running mostly conventional stuff and something new if I get one.

The one thing I can not seem to find is modern circuit protection  that is ready to go ,with out having to build it myself.

I am sure there are others that would mind having a product that one can add without breaking out the solder iron.

I would like something that could be install without much fuss.

I work with tec all day ,The latest project at work and is a $850,000 bust and the last thing I want is more of it when it comes to my trains .

Now the new stuff is cool and I wonder will some of this be running 15 - 25 or more years down the road .

I say this because while at the store ,a guy brought a steamer that had been not run in many a year. The tec in a few moments cleaned and a quick lube was running just fine.

Still would need a full service ,But it did run around the the test track.


Check this thread:

I found this excellent Magnetic circuit breaker.  Short of an electronic one like the PCX-AC, this is the best breaker you'll find.

Here's the spec sheet for the AirPAX Snapak Series breakers.  Here's a good price for them if you don't mind waiting a few weeks: Airpax PP11-0-10.0A-OB-V $11.00 for quantity one.

Last edited by gunrunnerjohn

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