Difference between CW-80 and postwar KW

Difference between CW-80 and postwar KW

Night and day.  The KW is a 190W (around 140W usable) pure sine wave transformer, and the CW is an 80W electronic transformer with a saw-tooth waveform from the electronic control.

The reason that many modern locomotives have issues with the old PW transformers is due to the fact that the way the PW transformer is designed, it requires some significant current to be flowing to generate sufficient DC offset to operate the bell.  Also, the KW rectifier may be on it's way out and not capable of generating the DC offset required.

John is right. A KW does not play well with a modern locomotive.  Reliable sound activation is one issue. Slow thermal circuit breakers is another issue.  Keep the KW for postwar and AC motor trains. On the other foot, use your CW for modern engines like your Berkshire locomotive. I would not recommend your MRC pack for modern engines. It puts out sharp waveforms that have been known for killing circuit boards.

I have been using an MRC Pure Power Dual for over ten years with no problems with DCS engines. The one side not working could be the direction button tab on the internal board. Sent mine in a few years ago and MRC fixed it for no charge.

The Pure Power Dual is a clean sine wave transformer, I think Chuck is talking about their electronic models.  The MRC Pure Power Dual has a large toroid transformer with two beefy wiper arms.  It also has a diode whistle/bell circuit, so it develops the DC offset with no need to have a load.

Thanks everyone for your responses. But I have 2 follow ups. If I'm going to switch to using CW-80s (I think I'll need 5, already have 2), will it be a problem with the Williams engines? It also sounds from gunrunner John's response that the MRC Dual is ok to use with modern electronics. Am I reading that right?

We're talking about this MRC, if so it's fine for modern locomotives.

That's the one. Looks like I'm going to send it in for repair. I might just get one 1 more CW. 3 CWs and 1 MRC Dual should handle everything I need. Thanks for your help everyone. 

If you just plain love your kw, there are threads on disc to diode conversions and whistle/bell buttons you can build pretty cheap&easy.

A better, much faster breaker could be added as well. (Or even lower amp fuses).... One per track is best and allows a much lower fuse/breaker, i.e., safer.

I kept the disc and went with an add on button box as some post war whistles don't like the diode, some new don't like the disk, and I run both together.

Also, the kw givees a voltage boost to compensate for the heavy draw of a PW whistle motor. Your old trains may slow down when you hit the whistle on modern transformers or whistle button box (MRC?> Don't know, no boost on the CW though)

Search for threads on TVS's to further protect electronics if you're goal is "bulletproof" as possible.(cheap insurance)

gunrunnerjohn posted:

We're talking about this MRC, if so it's fine for modern locomotives.

Just curious, does this have a smooth starting voltage from zero on up?  My CW-80 does.  Not sure if a postwar KW does or not.

John is right about the MRC transformers. I remember now a discussion a couple of months ago about MRC transformers killing circuit boards, it was the electronic 027 Tech series of power packs. Not the better ( in my opinion ) Pure Power series.

Paul, I don't remember the starting voltage on those, I had one a few years ago, but I sold it as I wasn't using it.  I did pop the lid and check out the hardware, it was a pretty clean and simple design.

My brother toasted half  dozen early MTH DCS before switching from the smaller MRCs to the Pure Power. Nothing lost after that.

MTH has a specific warning about some MRC transformers, doubtless your brother was testing their assertion.

The hobby shop (closed) was as much to blame as his not reading instructions; they pushed the MRC the same day. (He bought "bulk". I wasn't around...and he's not real "handy" , except for firearms.

I gotmy KW back because of that purchase though

The one issue I have with the MRC dual is most engines do slow down when I blow whistle. For that reason I'm looking to sell mine.     Lenny

Just to make sure I know all my options, my last question is will the CW be adequate to run the Williams engines? Most of these are dual can motors or one big can for the steamers.

I have only even ran two newer Williams (by Bachmann). For diesels, plenty of power in a CW80 with a smaller can motor on a normal Christmas tree circle/oval. 

The blink on starting a run;,could maybe be avoided by increasing throttle more slowly from a stop. Works for me with the 80w bricks&grey "dial box" that preceded the CWs (there is a CW40 too).  Once moving, the amps needed drops off fast. 

Older Williams with twin Pittman motors might be too much. Running those predates any concern by me for "solid numbers" on amps.  ????

Lennyski posted:

Just to make sure I know all my options, my last question is will the CW be adequate to run the Williams engines? Most of these are dual can motors or one big can for the steamers.

For right now, a Williams GP9 pulling 4 = Williams heavyweight 18" passenger cars (with 3 light bulbs each) seems to be about the max. my CW-80 can handle.  Or, it will handle 2 = powered loco's pulling unlighted freight cars.  Haven't tried more than 2 powered loco's.  I don't have anything hooked up to the accessory side of the transformer, either.  Probably wouldn't take much to start hindering the loco side of the thing, if the truth is known.

  The somewhat vauge answers are not your imagination; they are to cover the unknown variables so you aren't mad if it doesn't work out. Variables like a set of lighted passenger cars or a penchant for a fast take off, it will be close on the the CW80 imo.

  If you have 0.25a bulbs x3 x4 cars that is another 3amps right there. About what that can motor draws, maybe more, maybe less, but close (L.e.d. lit? Much less)

If your track or wire is poor, more output power is needed. If your engine runs slightly poorer than the norm, more power is used, etc etc. 

   We can only ballpark it when actual use comes close to the max. output. ... Even the transformers can vary in output.

   If it is shutting down, tripping fully and often, your slightly over the limit. If not, no worries. A modern transformer acts fast. One or two odd blink outs on start up, but not a full breaker trip, is not a huge deal. The unit is saying "uh oh... Never mind". Your heaviest draw will be from a dead stop.

Hot transformer,? You're possibly taxing it too hard; bigger would be better, cooler will last longer (in theory, no garantees) etc etc.