The top speed of a number of my analog locos is very slow using DCC. The same run at reasonable speeds using DC. Is this a natural occurence with some locos? I assume the slow running ones will also run slowly with decoders installed and have avoided installing decoders. Is this a correct assumption? Thanks, Ben
No, the max speed should about the same. If the engine runs with DCC another speed, the secret is in the CVs. :angel: Look at first at you manual, which value has the max. speed CV? Wolfgang
Hmm. I was speaking only of running analog locos using a DCC throttle with 00 as the loco address. Some locos that run at reasonable speeds using DC power barely creep when run on a DCC layout, thus my questions. Ben
Could it be the track voltage on the dcc system is low? If the track voltage is too low the locos will run slower. i have mine set for 12 v in nscale. just a thought.
I don't have practical experience of this but given the ginormous electrical/electronic frig that is used to allow DC to run on DCC I would not be at all surprised. I suspect the AC characteristics of the motor will play a part (yes, I do mean AC ) Following from the first point, I'd say 'no' (ie. not a correct assumption). If you install a decoder the motor is then being run off DC, much like a DC power pack. (From the motors point of view a decoder is really just a very small DC controller.)
I don't think how they run as address 0 is any indication of how they will run with a decoder. Except that they will almost certainly run better. Address 0 is a kludge.
A DC power pack will put 16-18 volts to the track while the DCC system, at least the one I have, puts 12-15 volts to the track. Your DC loco WILL run slower. Put a decoder in it and it will run faster under DCC.
Running analog address 00 will always result in a lower speed than normal with an analog engine. DCC systems that will run an analog engine use a method called zero stretching. This makes one half of the normal AC type wave last longer. One rail is "more positive" which causes the DC motor to think it's getting DC. Change direction and the other rail will be "more positive". Reason the speed is slower is that since the system needs to put out a DCC signal both rails still need to have some voltage and the total voltage is the sum of the voltage on both rails. So you engine will never see the full forward voltage on DCC as it does on DC. With a decoder installed the top speed will still be slightly less due to voltage drop through the decoder components buts it will be faster than without a decoder. Many prefer the slower speeds since full sped on most models is more like slot cars. Martin Myers
Martin, Thanks, this will help me make some decisions. In the "slot car" speed category are Kato locos which benefit from slower speeds. The opposite are Life-Like or Bachmann locos, many of which are "snails" even with DC. One that caused my concern is a Con-Cor N Scale 2-10-2 that barely moved when run without a decoder on address 00. I suppose I was hoping differently, but with a decoder installed it is still slow running even with top speed programmed at the maximum. But the top speed of approximately 40 mph is close to prototypical. It just "looks" slow. Maybe I will get used to it. Ben
I'd like to add one more question to this thread if I may, since it seems we're on the topic of the 00 feature already. When I run a DC loco with the 00 feature, the motor gives out a constant scream. Is this normal? What are the effects on the motor? Thanks
Mystere, et. al.; DCC is basically an AC square wave. DCC runs a DC locomotive by varying the widith of the high or low portion of zero bit pulses. This results in an average voltage greater or less than zero. However, you have to remember that for all the long pulses in the direction of travel, the motor is still getting short pulses in the opposite direction. And a zero speed is achieved by making the pulse widths equal. The motor is constantly being pulsed against its direction of travel. This is why a DC locos heat up a bit in 00 mode and hum even when stopped. In my experience some DC motors are more tolerant of DCC 00 mode operations than others. And it has nothing to do with the age of the motor; I've seen a 20 year old loco run fine and a brand new Kato one run like a snail. Mostly people just don't use 00 mode. Best!
Awesome, that makes more sense. Now, more specifically. I have the Kato GS4.. but the decoder and fix are still on order from LHS. My only option to run the loco while I wait for the parts is to use 00, so would using 00 damage the motor at all? Thanks.
I believe KATO would advise against it and void the warranty if damage results. I wouldn't because it is my opinion that any piece of machinery that make that much noise is being damaged. Martin Myers
I would wait for the parts... the "fix kits" are shipping now, so your wait shouldn't be that long. Best! Randall
