Now this may be a newbie question but the Bachmann stuff I have starts right up where it left off if you stop power to it, no restart each time power is interupted, have another (think BLI but could be MTH) that if power is interupted, it goes into startup mode again, to me this is anoying since I am still bullet proofing the layout.
Look for brands that include some form of “keep alive” system onboard or as an attached device.
Most new designs are finally acknowledging this big defect in DCC and including effective keep alives in their decoders.
Different brands may call this feature by different names.
The basic idea is storing enough power in capacitors* to feed the decoder and the motor over blips in continuity. For DC this was easy to do. For DCC the control signal aspect of the system also had to be electrically preserved.
- most common. There are other ways to achieve this apparently.
Not an annoying question at all. In fact, I think it is a very good one.
I do not use DCC, but I have run several layouts that do, and the “restart on blip” is annoying.
I would hope that only people that have actual experience with different decoders answer this question from real experience and we not go down into the “theoretical nonsense” rabbit hole again.
Looking forward to a good thread…
-Kevin
Are we talking sound decoders or motor only?
If we are talking sound, this is a common problem. I ended up retrofitting keep alives in my older sound locos. Large wheel based locos generally have robust enough pick up to avoid this issue. The other fixes are powered frogs, electrical pick up modification when necessary (especially old brass), and of course clean track.
I pretty much run exclusively with tsunamis but I have Bachmann, QSI and Wow sound decoder installs as well. They all have the same reset issues without a keep alive if power is interrupted for any length of time. The smaller caps that are old factory spec. will slightly smooth out the running but not enough to make a difference if the problem is really bad. The keep alive pretty much solves the issue.
Non sound decoders - I’m afraid I cant be much help as nearly everything on the layout is a sound loco…
Guy
In my opinion, it’s a very short thread. No one will be happy for any particular length of time running DCC sound without a keepalive on it. (One “alternative” in manufacturing is to have a timeout delay on the startup sequence so any interruption < something like 8 seconds continues where things dropped off – which to me is how things should have been designed in silico by anyone thinking about real model railroading for more than a few seconds – but I think including the keepalive is a better general solution.)
The discussion might be reserved for decoder architecture with an integrated small keepalive for the sound functions leaving the option to put in a larger (and bulkier) effective keepalive for the tractive power and lighting. That at a minimum is how I believe a thinking man would design this sort of thing.
Some folks don’t like ‘global’ keepalives because (for example) of the risk of runaway or unexpected activation. They shouldn’t be required to have them just to keep their sound constant across interruptions and spikes and the like. Which implies a split architecture…
Of course this is mostly theoretical: where are all the DCC mavens who know the state of the art in keepalive practice ‘as it is’?
I guess I am no one. I have only one loco with a keep alive, and it’s not even a sound loco - it came from the factory that way, and I haven’t had a layout to run it on since I got it.
With clean track and proper feeders (no relying on rail joiners to power track), there’s no reason for the sound to cut out int he first place. I haven’t had a problem on 2 layouts I’ve built. And even where I don;t control things, the club layout, the only place there is power loss are the fitter tracks between older modules, which have no power feed, just joiners linking to the powered track on either side. These always have power issues.
In fact, my train will be rolling around with nary a headlight flicker (except the fitter tracks) and others are calling for the cleaning train to be run. Not sure why their locos are running erratically while mine continue to chug along fine.
Some sound decoders can be programmed as to the behavior on power loss, so running the startup sequence every time can be disabled. MTH is one you can’t fo this, which is just one of the reasons I will eventually replace the electronics in my FA set. It’s especially annoying when only one of the units get interrupted - then pressing F4 to start up the dead one silences the working one.
–Randy
This reminds me vaguely of the arguments for keeping the unusual approach for brake implementation on the Routemaster bus: MY engine maintenance is perfect; my hydraulics flawless, and I always always check my oil level and quality before I set out…
At some point the ‘never no never’ might (unlikely as it is!) change to a ‘hardly ever’ … just as with that functionally developmentally challenged MTH-in-DCC-compatibility-mode stuff in its own inimitable ways … and the very first time it does you’ll remember this little analogy…[;)]
Been running sound since the first BLI GG1, that’s what, 20 years now? Long time for the ‘point’ to be reached. [:D]
I feel the keep alive is just covering up the symptoms of the illness, and not actually resolving anything. On the other hand, as long as the keep alive masks the poor pickup, you will continue merrily runnign traisn and not worrying about keepign the rails and wheels clean, until the day when it gets so dirty, even the keep alive can’t save you.
I’m also not a fan of autoreverses on trivial loops, where a relay driven by switch machine contacts can flip the phase before a short even occurs. Same with frog power, the Frog Juicers are reserved for complex trackwork where figuring out the polarity is next ti impossible, and for the trivial application of a single turnout, where which way the frog polarity has to be connected is quite obvious, just use switch machine contacts. Again, solve the problem before it becomes one, rather than wait for a short and then fix it.
–Randy
Ain’t THAT the truth. (And I should add I like Citroens with the DS hydraulics, which have the same little… problem, so it’s not like I’m actually criticizing the idea…)
I’m vaguely out of accord with the idea that keepalives will be the moral equivalent of protease inhibitors for wiring hygiene. I see no particular reason not to have thoroughly extensive feeders and both gleamed and well-maintained track and wheels, and have a keep-alive on the sound to prevent glitching for any unanticipated circumstance.
Ok, a lot of words but for the most part, no substance. The new Bachmanns do not have the blip problem. Now was this a CV setting or a decoder design.
To rephrase with more words, a decoder manufacturer could either solve the blip problem with a setting that would prevent ‘startup sequence’ for x seconds after a power interruption, or by integrating some form of keepalive ‘lite’ into the decoder for the sound function. If Bachmann did either in their ‘new’ design, it would only be overdue remediation of the problem. You could easily find which of the approaches it was by looking at their documentation, as easily as anyone else could… and save yourself even more words.
The problem is findign the ‘right’ parts. Space can be an issue, also expense, though DIY stay alives are pretty cheap. They also have a tendency to interfere with programming - the few exceptions are the fancier 3 wire units that ESU and Lenz have, among others. Those 3 wire ones also have a great advantage in setting a maximum run time - a 2 wire one runs until the caps discharge, no control over it.
They do come camll, if they can crame a motor, front and rear lights, a motor decoder, AND a stay alive inside the tiny Walthers Plymouth. The problem is, it makes the loco behave like a windup toy. It runs far too long on a charge - take it off the rails and it will roll across a non-conductive surface for 30 seconds at least, easily twice the length of an 8 foot table. Completely unecessary, if the idea is to cover for dead points or a dead frog.
Smaller switchers, that run slowly as a rule - i can see it, but still needs to be limited in run time. A longer road unit, 4 or 6 axle, with all wheel pickup - if that stalls then there is a serious wiring problem, or the pickups aren;t working. And a 4-8-4 steamer, with pickups on both sides of both the loco and tender - such a loco should NEVER stall on reasonably clean track. That’s a long pickup wheelbase. Far longer than even a #8 frog. And why not power them as a wiring standard? At least if you are using powered switch motors, most any sort beyond the basic snap switch have contacts to power the frog, so it’s effectively free, and benefits ALL locos and lighted cars, not just ones with capacitors added.
A lot of words? Sure, but if the power doesn’t drop out under the loco, the sound won’t restart regardless of the decoder brand or settings. What I don’t like is the completely unrealistic movement of the loco before the prime mover notches up. That’s more a concern for me than the startup sequence playing after a power interruption. If there’s no opti
There is a simple solution to all of this. Just use Loksound decoders with their proprietory keep alives (they call them ‘Power Packs’). The distance that the locomotive will run after the loss of power can be controlled easily so you don’t have to worry about rogue locomotives tearing through your scenery or plunging into the abyss.
Having said that, and despite the fact that I am a great believer in keep alives, I don’t see the need for them in larger locomotives. I use them in my two and three axle critters. I don’t install them in any of my larger locomotives. I will repeat what others have said numerous times:
-
Feed every piece of track,
-
Keep your track and wheels clean,
-
Power your frogs.
[2c]
Dave
This is the first place that the advantage of a sound-only, restricted-time keepalive becomes significant. If the ragged outside requirement is measured in seconds, an extremely small (and hence proportionally less expensive) supercap, probably in a size range suitable for SMD, does the job perfectly, even with the very strict overvoltage protection supercaps require.
Is there a formal issue with programming if the only onboard keepalive is isolated to the sound circuits?
Most certainly; that’s getting into dead-rail lite territory, where only intermittent track sections have DCC power, and wireless control provides much of the actual signaling to and from the engines. What I think is desirable is some way of programming the actual keepalive run time via CV; Mike Lehman will likely recognize this as dial-a-yield [;)] Those who want more keepalive can pay for it, and regulate it; those that dislike it, still can have run time ‘their way’, and in any case the sound functions won’t glitch.
[quote]
What I don’t like is the completely unrealistic movement of the loco before the prime mover notches up. That’s more a concern for me than the startup sequence playing after a power interruption. If there’s no option to disable that, I will always pick the decoder that restarts on power loss over the one that
[Y] +1
This is the best answer I have read so far. Gives the name of a good decoder that solves the problem, and how they do it.
-Kevin
ESU is pretty much the only one that provides that “dial a yield” operation. But you need their 3 wire keep alives. A cheaper smaller alternative won’t provide the same results, while naturally ESU recommends against using such, they will work, just the CV setting for run time will have no effect, nor will they be bypassed for programming (which does seem to cause issues when using the Lokprogrammer).
The start delay is also easily switched off, even if it is a much more realistic way to run. Through the use of Drive/Hold you can limit the speed. The change in BEMF is far to subtle to base a load limited speed on, unless you have room for really long trains that truly stretch the limits of the loco, and iof that were the only way to do it, you’d have even more unhappy users, including me, that don’t have room for a layout with trains that long. Before Drive/Hold, it was easy enough to simulate a heavy train with just mild momentum programmed in, and manipulation of the throttle - just another reason touch screens and buttons only were never ideal. A knob, you can twist wide open, the prime move steps up, but the loco barely moves, as you get closer to the desired speed, turn the knob back down and the sound and actual speed of the loco join nicely. But you need to be able to adjust the speed step quickly - a knob is easiest and a thumbwheel doable, but trying to precisely activate a touch screen or by using incremement/decrement buttons - just not happening. But no longer needed with Drive/Hold plus momentum - just crank the throttle, then hit the F key to engage the Drive/Hold as the train hits the desired speed and it will lug that heavy train in Run 8 as long as you want and not gain further speed.
Just more reasons I stick with nothing but Loksound. Still the most customizable of all decoders, too - at the price of a lot more CVs, but the biggest chunk of them is a simple table, the same things repeated over and over, so while there are a lot of CV nu
I don’t seem to have any trackwork issues. I did have a turnout that was slightly out of wack in the begining (the switch point rails were a little high, a very Shinohara type problem easily fixed). This caused one of the non Bachmann’s to stop and start startup again even though the Bachmanns sailed through unless I was going so slow I was barly moving. Main line is basicly a dogbone 11’x7’ L shape. I am up to 1/2 hour to move over this area. Just saying I am not geting these issues from bad trackwork, though most things can be improved in life.
Now where do I find all this documentaion, most I have found is CV list defauts.
Loksound decoders do have an onboard capacitor (very small) that is connected only through the sound section of the decoder to prevent sound drop-out during those nano-second glitches.
Loksound decoders also have a “memory” setting that will have the decoder return to the same sound / speed after a short power loss. I’ve never experienced any sound re-starts with my Loksound decoders (~50) after an intermittent power loss.
I have one Soundtraxx decoder (only because I haven’t gotten around to swapping it yet) and it is constantly restarting through the start-up sequence at even the slightest glitch.
Mark.
Ummmmmm sometimes its not anything to do with the layout, but garbage pickup and internal wiring on the locomotive (aHEM my Athearn RTR F units. STUPID train show purchase[8o|]). So couple that with an Econami decoder and a cheapo capacitor, you get lots of non layout related problems. Thank goodness a club member gave me replacement kato chassi for the stock Athearn ones. Lesson learned. Buy scaletrains F unit