Kato Unitrack and multiple crossovers

[Shinchipboard]

I have quite a bit of experience in using Unitrack. I recently built a small layout on a door with a double track circuit and a branch winding up to a terminus above.

I used three (analogue) controllers and when crossing using the fairly recent single crossovers I was finding the locomotive speed was all over the place due to the passenger coaches conducting power from one controller onto the rails controlled by another controller (and another if there was an inner loop to branch move). This depressed me somewhat.

I am planning a much bigger layout and I would not like a repeat of this phenomenon. I have included the main part of my plan where the trouble will no doubt happen again.

I know DCC would fix this but I have steamers that are not DCC friendly.

[Andrew Nummelin]

The answer is in the first paragraph of the illustration. Ensure the route of the train is only connected to one controller using a multi-way switch to connect a section to the desired controller.

[Shinchipboard]

3 hours ago, Andrew Nummelin said:

The answer is in the first paragraph of the illustration. Ensure the route of the train is only connected to one controller using a multi-way switch to connect a section to the desired controller.

Thank you for your reply.

Yes I haven't tried that before but I don't think that I could handle more than one train through that junction anyway. Other trains could be held at signals before the section quite realistically I hope.

[brill27mcb]

I think this depends on what you are calling "analogue" controllers. If they are traditional basic controllers that rectify household AC power to DC and then vary the voltage level of the DC (like the Kato S model), you can just match the voltage levels and polarity of the 2 controllers and the train should transition from one to the other smoothly. On the other hand, if they use pulse width (PWM) modulation circuitry (like the newer Kato SX, I believe) and vary the duration of intermittent pulses of DC instead of the actual voltage level, the pulses of the 2 controllers will likely not happen to be synchronized and in effect their separate pulses can combine into longer pulses, making the train speed jump up during the transition. What kind of controllers are you using?

 

Rich K.

[Shinchipboard]

21 hours ago, brill27mcb said:

I think this depends on what you are calling "analogue" controllers. If they are traditional basic controllers that rectify household AC power to DC and then vary the voltage level of the DC (like the Kato S model), you can just match the voltage levels and polarity of the 2 controllers and the train should transition from one to the other smoothly. On the other hand, if they use pulse width (PWM) modulation circuitry (like the newer Kato SX, I believe) and vary the duration of intermittent pulses of DC instead of the actual voltage level, the pulses of the 2 controllers will likely not happen to be synchronized and in effect their separate pulses can combine into longer pulses, making the train speed jump up during the transition. What kind of controllers are you using?

 

Rich K.

Thanks Rich,

You may have hit the nail on the head with your observation. Confession time. I have used DCC for quite a few years now but I do not have the guts and probably eyesight to fit DCC to Kato lovely Japanese steam locomotives. I was a bit shocked (pun intended) by the price of Analogue controllers so needing three I was persuaded to buy the tiny offerings available on a bidding site. I wondered if they would harm my motors so I got opinions from independent users. In the past I have just set the identical controllers to the same setting and no speed difference was observed. I thought that the inbuilt pick ups on the Kato coaches was bridging the gap. Im an electrician but not into theory i,e 12v + 12v = 24v? No the speed difference is not of that magnitude so I think your observation is the likely cause.

 

kind regards

Doug

[brill27mcb]

Can't beat the price on those little controllers!

 

There's nothing wrong with PWM controllers. In fact they help make "constant lighting" operation possible with analogue control, especially now that LEDs have largely displaced incandescent bulbs in rolling stock. A DC motor with windings on an iron core is slow to react to the short, frequent pulses and tends to average them out, while LEDs respond immediately to the 12 volt pulse and light up. PWM can also get a motor turning earlier as you slowly turn up the control dial, so you can get better starts. But the momentary jump while bridging insulated track joiners separating 2 PWM sources is a downside. The solution is to go to block control with something like toggle switches, and flip the blocks to run on the same controller before you cross the gap between them. That's a step up in complexity, though.

 

Rich K.

Edited December 12, 2021 by brill27mcb

[cteno4]

In this case 2 pure dc feeds would not double the voltage as they are wired in parallel. The one with the higher voltage will take the load though. If the power supplies were wired in series (not something happening here) they voltage would be the sum of the two voltages.

 

with pwm you are in parallel, but the power supplies are not in sync thus you will fill some of the gaps (no voltage cycles) from one power supply with power cycles from the other one. Probably not good for the power supplies as load would be switching back and forth a lot.

 

jeff

[Shinchipboard]

I foresee many pages and coloured pens before I settle this one. 🤮.

I see nobody contradicted me about fitting DCC to D51, C62, C11, C59 etc. 

Yes the lighting is very good on these PWM controllers. I like a lot of other people find switches more satisfying than DCC dialling.

I wont be building any time soon so no updates till then. Thank you all. Doug