Hi,
I don't yet have a proper layout, only a test track but I have 5 locos that I have made and installed a variety of DCC chips in.
I have found that my 4 wheeled locos are quite unreliable at slow speeds, even on seemingly clear and clean track. My garratt, with 2 minitrix 0-6-0 chassis, doesn't have many problems at all in comparison. My darjeeling D class is quite heavy and works quite well too.
Does anybody do anything to make DCC more reliable on little locos? I've installed a couple of 200uf capacitors for one of my locos with a kato tram chassis and it has made it better, not perfect but better than it was. The main problem I can see with 009 and DCC is lack of space for the electrical gubbins. Its hard enough finding space for the DCC chip without trying to fit capacitors all over the place.
Any help/advice would be appreciated.
In case anyone was wondering about the capacitors, they're wired to a TCS M1 encoder. I've wired them to the same points that the TCS M1-KAC decoder has its keep alive wires attached to. I've attached pics of the setup anyway.
I model US prototypes in HOn30 with DCC and my aim has been to get running as reliable as US HO SG.
This is a challenge but I am getting there
I use the TCS Z2 decoder as standard but also others on occasion
My keys to good running are very much the old favourites; clean track and wheels, switched frog points with the point blades connected to the adjacent stock rails, reasonable weight in the right places and as many pick-ups as possible. I only have one 0-4-0 with stay alive and I cannot say for sure it is better than my other 0-4-0s
I clean my track with surgical spirit before EVERY running session and my loco wheels never get dirty. Some say this has additive(s) but it works for me. Others use graphite rubbed on the track but I don't like anything that potentially contaminates the track. I don't have gradients but some say graphite is not good with them and I can understand why
My tender locos all have tender pick-up as well as loco and I do have excellent running. My diesels tend to use quality chassis (Atlas/Kato) and are the same. I only use new Minitrains 0-4-0s and can get these to run very well.
I have to say that although many swear by the Kato 4 wheel chassis you are using in your lovely loco I just cannot get on with them. It is crucial when installing the decoder not to disturb the pick-ups on re-assembly and I honestly find this difficult. Some rub on the wheel backs, some rub on top of the flanges but I find it hard to be quite sure this is the case.Whatever, I cannot get reliable smooth running. So if you find an answer please tell us here. I am sorry I cannot comment on the capacitors on your Kato chassis but in theory you should get excellent running with them fitted.I suspect though your problem is with the pick-ups
I have had good results with Tomytec chassis, again using the TCS Z2 decoder but here it is easier to install the decoder without disturbing pick-up reliability
Sorry I haven't solved your problem but hope it helps as I am a committed DCC user
Peter Smith
I do not use DCC but with DC I find that the more weight is on the driving wheels the better the slow speed running of small locos. Light weight locos are not so good.
So try adding weight to the locos and see if this helps.
This is one disadvantage with DCC in small locos in that the space that could be used for lead weight is filled with the somewhat lighter DCC decoder and in your case a couple of capacitors as well.
As mentioned above the pick-ups can also cause problems. Make sure that the soldering has not resulted in a re-alignment of the pickups and that they are making good contact with the wheels.
With DC you can just turn the loco upside down and run it with a couple of wires touching the wheels to test the pickups, but this may not be as easy with DCC.
Brian Meldon
Thanks for the replies.
I've gone and bought some liquid gravity off ebay now to make everything heavier.
Michael
would be interested to know if the weight improves your Kato 4 wheel chassis and by how much
Peter Smith
I am not into DCC, but have experience with getting better running. I am sure that the key is, whether DC or DCC, clean track and wheels, and, as mentioned, well adjusted pickups. DCC is not a cure for all ills, but relies equally on the voltage getting to the chip. I am aware of "stay alive" systems with sophisticated DCC chips and capacitors, which may help getting over temporary spots. Since you say that your twin chassis Garrett has less problems, I would look first at the pickups on your Kato's, as suggested, and then reinspect the cleanliness of track and wheels. When it comes to a layout, well laid track is also important.
As several posters have mentioned, weight is the key to better rail/wheel contact. You can try everything such as Railzip, graphite or (for DC layouts) a Relco, but start with weight. Most of my locos weigh 80g or more, and they really push down through the dirt. DCC has one advantage over DC in a permanent higher voltage applied to the track. But if the loco is too light to make an impression on dust particles on the railhead, you're nowhere.
Apart from liquid lead, use sheet lead inside the skirts (if you can), under the roof, etc.
Alternatively you could go for radio control with on board battery power and get very reliable slow running!
Frank
Quote from: tedp on January 19, 2015, 19:33
As several posters have mentioned, weight is the key to better rail/wheel contact. You can try everything such as Railzip, graphite or (for DC layouts) a Relco, but start with weight. Most of my locos weigh 80g or more, and they really push down through the dirt. DCC has one advantage over DC in a permanent higher voltage applied to the track. But if the loco is too light to make an impression on dust particles on the railhead, you're nowhere.
Apart from liquid lead, use sheet lead inside the skirts (if you can), under the roof, etc.
I do not get on well with liquid lead. The lead I use is from used stick on car wheel balance weights cleaned up then cut and flattened as necessary using a small vice and a sharp knife.
I did try both Railzip and some years ago graphite but I found that although they did help a lot with loco to rail electrical contact they both reduced the hauling abilities of the locos up grades considerably so were no use to me, but others have used these products successfully. I just use a fine track rubber to clean the track each time I use the layout.
Brian Meldon
From my limited experience with Blaenau North its all about:
clean track, clean track, clean track
Electrical bonding of points
Electrical continuity of every section of track (don't rely on the fishplates to conduct current)
Checking that every point runs through OK
Careful cleaning off of ballast , especially on the sides of track.
For lead, I bought a roll of lead flashing a long time ago and that's what I use , secured in place with Araldite
Robert Berry
We also have been using Fleischmann track cleaner loco chassis for many years. I have three under different steam outline tram bodies and one is always on the layouts when they are in use.
As well as a nice running chassis that appear to last for ever (although I have known the plastic gears on the axles to snap) they have two sprung revolving disks with fine emery paper that keep the track clean as the loco runs.
But while these locos are very good at keeping the track clean during running sessions and at exhibitions I still clean the track manually before every operating session and clean all the wheels on every loco before an exhibition and also often before I use them on the layout at home.
Cleaning the wheels is easy with DC using a couple of wires from an old Triang controller and with the loco held upside down in a foam cradle. But I understand that this may not be so easy to do with DCC.
Brian Meldon
I'm one of these creatures who likes to cram as much weight into a loco as possible. The heavier it is, the less chance there is for lifting off the rail, arcing and leaving deposits to catch the next loco. Balancing the loco with good weight distribution is also very important. Combined with clean wheels and track (and well-laid track) this will make for pretty good running.
I have some lead flashing but also, whenever I'm at exhibitions I'm always on the lookout for whitemetal casting which can be useful for weighting locos. Examples are lineside cabinets, boxes etc
Whitemetal oildrums are useful boiler inserts.
David.
I have used Kato Chassis 0-4-0 with Digitrax DZ125 decoders without problems. I agree with all the others who have emphasised that weight is the key to good running. For this reason I am careful which locos I have chosen to use under DCC. The 3D printed diesels I have built all have good amounts of space for lead. I use 2mm lead sheeting from Eileens Emporium. With lead I always use superglue as it will react with PVA and swell causing damage to loco bodies.
Hi Michael
I may be wrong, but the two electrolytic capacitors appear to be wired in parallel but with opposite polarities - i.e "+ to -" and "- to +". If I am right then at any one time one of the capacitors is seeing reverse voltage across it. At best, there will be high leakage current through that capacitor (reducing the storage effect of the other capacitor) and at worst it could overheat and split the can.
Peter N
Quote from: PeterN on January 24, 2015, 23:25
Hi Michael
I may be wrong, but the two electrolytic capacitors appear to be wired in parallel but with opposite polarities - i.e "+ to -" and "- to +". If I am right then at any one time one of the capacitors is seeing reverse voltage across it. At best, there will be high leakage current through that capacitor (reducing the storage effect of the other capacitor) and at worst it could overheat and split the can.
Peter N
The traditional 'trick' with ac is to connect two identical electrolytic capacitors in series (not parallel) and back-to-back (+ve to +ve or -ve to -ve) to make a non-polar electrolytic capacitor.
http://electronics.stackexchange.com/questions/35480/polarity-of-unmarked-smt-electrolytic-capacitor (http://electronics.stackexchange.com/questions/35480/polarity-of-unmarked-smt-electrolytic-capacitor)
There a good number of reports online that this is not recommended though. Also the capacitors in this application are not being used with ac but with dc that reverses polarity occasionally.
However, electrolytic capacitors in general can withstand a small amount of reverse polarity. For the can type shown in the photo then perhaps a volt or a volt and a half. Putting a diode across each capacitor to discharge it should keep its terminal voltage to under a volt. Depending on the diodes and the capacity then a resistor in series with the diode may be needed to limit the discharge current.
Another thing to bear in mind is to make sure the capacitors are running well below their rated voltage.
(https://forum.009society.com/proxy.php?request=http%3A%2F%2Fwww.electronicspoint.com%2Fattachments%2Fbipolar-capacitor-w-diodes-jpg.5149%2F&hash=4c1fa8122f0463ddbd804317b4d4c0515fb46e3a)
from: http://www.electronicspoint.com/threads/normal-electrolytic-capcitors-as-non-polarized-bipolar-ones-in-ac-circuits.251027/ (http://www.electronicspoint.com/threads/normal-electrolytic-capcitors-as-non-polarized-bipolar-ones-in-ac-circuits.251027/)