Kato N scale FEF TCS DCC problem

[woodone]

Here is a shot video of my LokSound Select decoder install.
This is a test sound file.

[woodone]

Don't know why this will not play here. Look on you tube to see it I guess.

[EspeeGoldenState]

I'm curious at what speaker some use. Everyone says what decoder but fails to usually say the speaker type.

I'm planning on doing the two decoder set up for time being with the TCS and Tsunami and planned on using a RailMaster DS1425-8.

Has anyone used one of these speakers before and how does it sound with steam? Almost same dimensions as the Soundtraxx one, wasn't sure if it would fit though.

Chris

[peteski]

I've been thinking about this compatibility problem.  There is a solution worth a try for the coreless unfriendly decoders. This is a trick used by the Nn3 and Z modelers to reduce the voltage when using the pager motors used to power their tiny models.  Recent N-Scale Magazine article reminded me of this technique. Basically it is 2 Zener diodes hooked up in the following way:
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The diodes reduce the voltage going to the motor.  I imagine 3 or 5V Zener might be worth trying.  Since DCC decoders use full voltage pulses to control the motor speed at all throttle settings (only the duration of the pulses changes), the Zener diodes would reduce the voltage of those pulses.  It might help with slow speed. It will also reduce the top speed, but with Kato locos, this is usually a desired effect. 

Zener diodes are inexpensive - it woudl be worth trying them. Just buy diodes with appropriately sufficient power dissipation rating. Diodes rated for 1 or 2 Watts should be robust enough to handle the load.

[jdcolombo]

Here is a shot video of my LokSound Select decoder install.
This is a test sound file.

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Nice sounding!  This is the experimental FEF file from ESU, right?  I hope they get it posted for the rest of us soon!

John C.

[woodone]

The speakers that I used are 10 X 15 X 8 with an enclosure. I used two speakers. I do not know who makes the speakers but I got these from my supplier( Litchfield Station). Called Sugar Cube.  One in front of the weight and one to the rear of the weight. These are wired in parallel for a 4 OHM load.
NO holes were drilled into the floor. The decoder sets on the weight and is held down with some double sided tape.   

[woodone]

Any one wanting this sound file should contact Matthew Herman.
Matthew.Herman@LokSound.com

[TrinityJayOne]

Thought I'd chime in on this as my brother just got a factory DCC FEF-3 and I have a fair amount of experience with TCS decoders. I've put them in diesels old & new from several manufacturers and every single time the crawling performance has been nothing short of perfection with absolutely zero configuration. Here are two videos I made a little while ago that demonstrate this wonderfully-

and

.

I don't think the decoder is to blame with the FEF-3, I think it's a combination of Kato's new mechanism and the fact that the loco is sporting drivers roughly twice the diameter of the diesels shown in the above videos.

[peteski]

I don't think the decoder is to blame with the FEF-3, I think it's a combination of Kato's new mechanism and the fact that the loco is sporting drivers roughly twice the diameter of the diesels shown in the above videos.

The point being made is that there are decoders out there with motor control circuitry which allows full control of the coreless motor (from 0 rpms to full speed).

Coreless motor is just another type of a permanent-magnet DC motor.  But it is a lot more efficient than standard motors with iron-core rotors, and it has different electrical characteristics.  The designers of the decoders which are capable of fully controlling the speed of the coreless motors took those characteristics into consideration.  So you can't just say that the motor is the problem here because it clearly is not.  It is just a compatibility problem between the decoder and motor.

[TrinityJayOne]

It's less a case of ESU, Zimo, etc '[taking] those characteristics into consideration' and more that their existing design just happens to work because the BEMF can be manually tweaked, whereas TCS feel their algorithm is good enough to lock-out such settings from the user (and for 99% of locos they are probably right). I never said the motor was at fault, I just feel some people are suggesting the TCS decoder is somehow bad/dodgy which I think is unfair. Some testing from either or both parties would have solved the issue...or perhaps they knew about it ahead of release and decided that pleasing those who care about crawling wasn't worth the added cost and delays.

Either way, I'm sure that something will change in the future if we see a resurgence in coreless motors (personally I don't see the benefits).

[peteski]

To me your statement "combination of Kato's new mechanism and the fact that the loco is sporting drivers roughly twice the diameter of the diesels shown in the above videos" implied that the entire mechanism (motor, gearing, etc.) was to blame for the problem.

Coreless motors are better than conventional iron-core rotor motors. The reason they haven't been widely used in model locomotives was mainly the high cost.  But now cheaper coreless motors are being produced in large quantities (thanks mainly to the introduction of inexpensive electric RC helicopters few years ago), so model train manufacturers are beginning to incorporate those motors into their models.

As far as the other decoder manufacturers just getting lucky, I doubt that is the case.  The decoder manuals specifically mention settings for coreless motors (some decoders even have special mode for coreless motors). I don't think that this happened by chance.

[TrinityJayOne]

Fair enough then.

In your opinion, what makes the coreless design superior? As I understand it they weigh less, draw less current and accelerate quicker, but how does that make a difference to our model trains? Generally you want them to weigh as much as possible to aid traction. If faster acceleration was needed we wouldn't be having a discussion right now on making our trains slower or seeing flywheels listed as train features. As for current draw, in my experience it is sound chips that do the most damage here, unless you run trains fast enough to challenge world land speed records that is. Running at prototypical speeds I see my locos struggle to draw 0.1amp each.

So where's the benefit? What am I missing?

[C855B]

What you're missing is coreless motors have superior low-RPM performance because there is no cogging to overcome. Cogging is a product of ferrous armature poles. Coreless yields smooth torque in very small motors starting at 0 RPM.

[jdcolombo]

It's less a case of ESU, Zimo, etc '[taking] those characteristics into consideration' and more that their existing design just happens to work because the BEMF can be manually tweaked, whereas TCS feel their algorithm is good enough to lock-out such settings from the user (and for 99% of locos they are probably right).

Actually, the European decoder manufacturers DO "take those characteristics into consideration."   The explanation I've been given by folks in Germany and Austria is that a large percentage of their models (particularly small steam) have used coreless motors for years, and therefore the decoder manufacturers had to engineer their mobile decoders to take this into account.   Zimo's manual, for example, specifically lists which CV's to change (and which values to enter) for coreless motors.   ESU's manual doesn't give specific values, but does tell you what you should change (and in what direction of change) to find the best fit for coreless motors.  Lenz's silver and gold series have five motor "pre-selects," two of which were designed with coreless motors in mind and have further adjustable parameters than the other three.

My understanding of the advantage of coreless motors is that they run more smoothly throughout their speed range (no core; no cogging, and very little mass to overcome on startup) on pure DC, develop higher torque more quickly, and are lighter.  As you note, the "lighter" part really isn't an advantage in model railroading, but the smoother/more torque on pure DC part would be for those operating on regular DC.  Notice that NO ONE who runs the FEF on straight DC has complained about the engine's smoothness at low speeds - just the opposite; they all rave about it.   So I can understand that from Kato's perspective, the coreless motor resulted in the smoothest, most powerful design for what is still the "standard" for model railroading: straight DC.

I DO fault both TCS and Kato for not doing a bit more testing of the TCS board.  Since this board is specially made for the FEF, TCS presumably could have altered the BEMF parameters in their firmware in order to address the issues.  It's not like you're going to pop this decoder into an SD70Ace.  And at least a couple of people have reported no issues at all with the TCS decoder, though I find this hard to believe (I suspect their standards for low-speed smoothness aren't as demanding as mine - which is fine.  I'm very picky on this point and probably an outlier in my demands).

In any event, the main point here is that other decoder manufacturers HAVE designed their decoders specifically for coreless motors.  It wasn't an accident.

John C.

[C855B]

Question mostly for Pete and John... any thoughts about putting a bipolar electrolytic across the motor leads? If the motor really works best on DC, then feed it DC. Yes, a cap is old-school if not brute-force, but it's a thought. A 10uF/35V bipolar is 5mm x 11mm... is there room?