I only recently discovered the CN decoders we're talking about here. I've installed four and consisted the engines and they performed absolutely flawlessly! I think I'll have to help stimulate the economy with as many as I'm going to need to bring my old stuff up to date!
The trick is to get the locomotives speed matched. If their speeds are matched, BEMF does not fight itself. Don't quote me on this, but isnt it possible to use BEMF to automatically speed match two+ locos?
I never had this problems as all the locomotives in my "ABBA" consists are speed matched and don't fight each other. The trick is to turn off the BEMF before speed matching these consists. After all locomotives in the consist are speed matched, you turn the BEMF on again. and then there are no problems that are described above.
Kind of but not really. If they are running perfectly together, and neither one hits a dirty spot of track (to slow it down just that tiny little bit) or there are no grades or you are not pulling a train, then yeah, I guess it's possible. But if one slows down just a bit and the other one has to pull/push, then the BEMF kicks in and then they start fighting. If you are pulling a train, then you are putting weight resistance on each loco and in essence each loco is trying to pull, then the BEMF kicks in and you could start to have problems. I don't see how this would be possible. If you read that whole page I linked to, it will tell you what BEMF is and how it's implemented. I have a TCS CN-GP decoder installed in a GP35, and it comes from the factory with BEMF on. When it's run in a 3-6 loco consist, it becomes a P.O.S. so I turned it off and it runs just fine now with the rest of the locos. Here is another read on BEMF: http://siskiyou-railfan.net/e107_plugins/forum/forum_viewtopic.php?5765.0 Seriously, I don't want this thread to turn into a pro/con BEMF fight, I just put the suggestion to Inkaneer that he could save some money by not getting decoders with BEMF because he's running ABBA consists. Through alot of his posts, he makes it clear that he doesn't want to spend alot of money for DCC, so if he can cut corners here and there, then more power to him. -Mike
I'm a DCC newby and I absolutely recommend the TCS Split Board Decoders. Yes you do have to file the frames a little to make clearance for the components on the boards, yes you have to file a groove in the motor frame to hold the gray wire in place but as to the BEMF issue, as mentioned, just turn it off. They run great. I've done 2 Kato C30-7's and a Kato SD-45. I've got 1 more CN -GP in hand and I'm torn between putting it in a GP-35, SD-40 or another SD-45. To your original question Inkaneer, take it from a newby, you'll love DCC. I took Powersteamguy's and other's advice and jumped in with both feet. I can't believe I waited as long as I did to switch.
It's getting harder to find a decoder that doesn't have BEMF, but the Digitrax and TCS ones both have a CV, IIRC, that you can use to turn OFF the BEMF if you don't want it. Even a couple years ago, BEMF was sort of like a "premium channel" on cable, but now it comes in most "basic cable" packages.
I've researched BEMF before and my reason for thinking it is possible to use BEMF to speed match is by having one loco BEMF enabled, the other dissabled. When they run together, a program could monitor the BEMF resistance of the enabled loco and interperat the data into a speed table so that it operates in precise relation to the dissabled loco. If the BEMF enabled loco is slower, the BEMF attempts to slow it down more because the faster loco is pulling it, so the program would write a speed table to give the BEMF enabled loco more juice at that speed step. There are also ways of fine tuning BEMF to ignore small hiccups like dirty track. In any case, I would think an N scale train pulled by an ABBA consist would have little effect in dragging/pushing the train anyways. Its a trial and error situation for these kinds of things.
My brother and I have used the TCS CN and CN-GP decoders in a variety of older Kato Atlas and Life Like (GP20, GP60) diesels and all work well and install easily. TCS's website has a lot of excellent illustrated installation instructions for a wide selection of units. One thing to remember is the golden rule that applies to any decoder installation, make sure the motor is isolated from the frame, a couple of pieces of strategically placed Kapton tape will save you from frying a decoder, my brother fried one but he sent it to TCS and they gave hom a new one.
Like Calzephyr, I've just been hanging out the past 20-25 years watching this technology improve, waiting for things to finally get small enough to entice me. The new decoders sound great, and I'm tempted. But has anyone here tried installing one in the old LifeLike locos, like the ancient FA2? That runs so beautifully I could never get rid of it. A powerful mover. Or the old GP-18? A really nice runner and beautifully painted and detailed. I don't remember when I bought these. Possibly early 90's.
Ahh, never mind. Found a place on the website where the models are specified. Only the newer versions of my locos are supported. So still waiting...
There's always the hardwire option. It seemed more daunting to me until I practiced my soldering and got back up near the level where I used to be when I was in high school.
I got one of the TCS CN decoders, and it went in with little fuss. It works fine, but I had a problem getting it to accept 4 digit addressing. After using the add, subtract, multiply, divide, click your heels together method of getting 4 digit addresses to work, to no avail, I gave up and made the address the last two numbers of the engine's road number. Someday, I may go back and give it another run through the programming track, but as long as it works well otherwise (it does), I'll probably leave it alone.
Try this program below. Just plug in your locomotive address, and the program will calculate CV 17 and 18 for you. It works all the time. Have fun.... CALCULATION OF CV SETTINGS FOR 4 DIGIT ADDRESSES http://ruppweb.dyndns.org/xray/comp/decoder.htm
Let's go back to the BEMF issue. I never run a single locomotive. Everything gets at least two locomotives. SOOOOOOOOOOoooooooo, do I need BEMF at all? What does BEMF do?
I have done that with the decoder. I have programmed CV17 to 221, and CV18 to 98, to get a 4 digit address of 7522. When I do a read back, it shows the 4 digit address as 7522, but it will not respond to that (or any other) 4 digit address. The engine is now simply "22". I've been able to adjust CVs for maximum, minimum, starting voltage, even normal direction of travel, but that one niggling thing keeps the install and operation from being "perfect". Will I get more of the CN decoders? Yes. I have a pile of non-DCC-friendly units to perform this operation to. It's certainly easier than a complete hard-wire, like I had to do to a Life Like/Walthers GP38-2 I have.
Here is a good article on BEMF from Tony's Train Exchange. Do you have any prominent grades or sharp curves on the layout? How long is your average train? With no grades, broad curves, and short trains, you could probably do with out BEMF all together. With the opposite, you would benefit from BEMF quite a bit.
