SeeYou190 gregcit made a very audible crack when we did.The bus that I posted a picture of earlier sounded like an MG42 firing a full belt when it accelerated under capacitive/generator hybrid power. The noise was extremely annoying to passengers, and anyone else within 100 yards.
gregcit made a very audible crack when we did.
rrebell ...then what happens with more, can it go 10 feet or?
...then what happens with more, can it go 10 feet or?
Thanks for clearing up your question.
The answer is: "Yes!"
Ed
The bus that I posted a picture of earlier sounded like an MG42 firing a full belt when it accelerated under capacitive/generator hybrid power. The noise was extremely annoying to passengers, and anyone else within 100 yards.
-Kevin
Living the dream.
To make it simple a capasitor like Keep Alive can power some engines for two feet, so if that is the case, then what happens with more, can it go 10 feet or?
rrebell With Keep Alive's allowing trains to keep moving, what would happen if you used more than one and if so, how many. What am I missing.
With Keep Alive's allowing trains to keep moving, what would happen if you used more than one and if so, how many. What am I missing.
More than one what? A Keep Alive on each and every locomotive?
What am I missing?
Rich
Alton Junction
LastspikemikeI referred only to high energy capacitors. I've seen warning labels on high energy capacitors.
certainly you need to be careful with high voltage capacitors.
i worked on a laser in college that used a couple 4F 600V capacitors (4x4x8"). we used a battery cable to discharge the capacitor after use. it made a very audible crack when we did.
LastspikemikeHow "big" would a 14volt capacitor have to be to power an HO locomotive in a useful way.
i calculated in the "Keep alive device, worth it thread?" that 4 1F 5.5V super caps in series stores 3.6 coulomb, 52 joules of energy.
a 1F 5.5V super-cap is about the size of 3 knickles stacked together.
greg - Philadelphia & Reading / Reading
LastspikemikeThe topic was about powering a locomotive with larger capacitors than a keepalive.
The capacitor may charge to the highest available voltage, which for power AC can be peak rather than RMS (it is common for smoothing capacitors to reach something like 161V on a nominal 120V line) but this is immaterial for any DC system, of course, and DCC modulation does not behave different from 14VDC or so with respect to keep-alives.
You can easily use voltage-to-voltage conversion to regulate the 'output' voltage from a capacitor as it discharges -- both to lower it when fully charged, and boost it when nearly discharged. That is little different from voltage management when using a battery.
This reminds me of some of the 19th-Century theories of locomotive boiler explosions, which supposedly involved 'thousands abd thousands of psi' of instantaneous explosion pressure if the 'supercritical' water were suddenly depressurized. It turns out you can certainly generate that kind of force... but not as steam pressure, and a moment's reflection should show you why not
yes it is.
regardless of the size of a capacitor, 0.1uF or 4F, it's the voltage rating that is cause for concern (a possible danger).
just as you probably don't want to touch the leads of a 100V power supply, you wouldn't want to touch the leads of a capacitor charged to 100V. (you certainly have no worries about touching the rails of a track at ~14V)
when people discuss using larger capacitors for keep alives, they aren't suggesting higher voltage capacitors. either they are suggesting using additional capacitors wired in parallel or using larger capacitance capacitors (e.g. 1F). in either case, the voltage rating of the capacitors need only be ~16V and even if rated higher, would only ever be charged to track voltage, ~14V
Hi rrebell,
In my opinion (which is probably useless), if the track and wheels are clean and there are sufficient power feeds, the need for keep alives should be minimal. I use them in my two axle critters mostly to get them through turnouts. I don't use them in any of my larger locomotives because, if the above conditions are met, the locomotive should never lose power.
I think that installing larger capacitance is actually a recipe for disaster. If the keep alive can power the locomotive for let's say 10 seconds, the locomotive is going to keep moving for 10 seconds without any control. That will surely lead to collisions and/or trips to the floor. If you say that you can just hit the stop button, that won't work. If the stop command does work that means that the locomotive is receiving power and control signals from the track. That would mean that there is no need for a keep alive at that point.
I use Loksound 'Power Pack' keep alives. They allow the duration of the keep alive output to be controlled. I set mine for about one second which is more than sufficient in my experience.
Cheers!!
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
LastspikemikeI had understood that capacitor voltage is regulated down to the desired output operating voltage but outside the capacitor itself
the capacitor(s) in a keep alive is charged to track voltage (~14V).
when track power is lost, it supplies current to the motor and decoder which has a regulator to drop the voltage to 5/3.3V. the motor operates at the capacitor voltage which steadily decreases until track power is resumes
I have seen stuffed animals with safety warnings.
CSX Robert rrebell With Keep Alive's allowing trains to keep moving, what would happen if you used more than one and if so, how many. What am I missing. If you loose power to the rails, the loco would do one of three things: Continue running until the "keep alives" ran down. Continue running until it reached the decoder's DCC timeout (often adjustable with CV11, the NMRA recommended CV for the timeout value). Continue running until it ran into something or off the track. With regular DCC it would not be like dead rail because without track power you have no way of communincating DCC commands to the locomotive.
If you loose power to the rails, the loco would do one of three things:
With regular DCC it would not be like dead rail because without track power you have no way of communincating DCC commands to the locomotive.
To that list I would add:
4. Continue running until it hits rails that are powered by the DCC system (back to normal). This is what typically happens.
rrebellwhat would happen if you used more than one
the larger the capacitance, the longer it would run without track power
LastspikemikePlus high energy capacitors have safety issues associated
huh? at model railroad voltage?
Five million dollars worth of capacitor hybrid technology, we were only able to keep it on the road for a few months.
This was a first generation field test of the technology. It was a fascinating project, and paved the way for much better stuff to come.
Thats what I was wondering, kinda like hybred dead rail much easier than true dead rail.
Simon