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My hi-rail S scale locomotive is equipped with a SoundTraxx Tsunami decoder and pulls a four-car consist of relatively heavy passenger cars over a 12-foot-long oval loop of track. The loop is connected to a Digitrax Zephyr DCS50 command station and PS315 power supply. I am very disappointed because even at max throttle, the train moves quite slowly. I asked Litchfield Station [from whom I purchased the DCC system] what additional Digitrax components I would need to buy to increase the peak speed.

The Litchfield Station tech guy stated that before he can make his recommendation, he'll have to know how much amperage is being used at full throttle [presumably while the entire train is running]. How can I  measure this parameter?

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If your PS315 is only rated a 3 amps it is probably too small for your train.  My Lionel LW is rated for 6 amps and average size trains with PW lighted passenger cars often draw more that 3 amps output.

I know this as I have a Amprobe clip on ammeter that I can connect to any of 3 Lionel LWs transformers and measure what amps a train is pulling.  I have had the ammeter for 30 plus years and it is rated for 25 amps.  I use is check the draw of appliances around the house and shop.  It has an adapter that lets you plug in the cord of item into and read the amps without cutting wires.

The Amprobe amp meter has a small area to show the 0 to 5 amp range and is hard to read.  To amplify this area to 5 times its size I made a simple 5 loop wire donut that changes the max reading from 25 amp max to max of 5 amps.  With a clip on ammeter I only need one meter and can move it to each LW .  They all have a 5 coil donuts.


Picture of $25 Amprobe Clamp on Ammeter, note the compressed area of 0 to 5  amps on the left of the scale.

IMG_1690



Picture of 5 turn coil, LW transformer and Amprobe clip on ammeter, reading scale for 5 turn coil in service are the big numbers added on with tape.

IMG_1694

A Amprobe clamp on ammeter would be useful all over the shop and house, uses no batteries and does not need to be hard wired in.

Charlie

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Last edited by Choo Choo Charlie

Bob, if you are pulling four AM Budd cars with your AM Pacific the total current draw will be under 3A. If you add a few more of the AM Budd cars with the incandescent bulbs and run a two motor Lionel S gauge Legacy engine in DCC mode you will likely exceed 3A. Definitely get an RRampMeter. Also consider adding a booster. A 5A booster should suffice until you begin running multiple trains.

If this helps I ran some comparable trains and noted the current draw. This is with Legacy/TMCC but I suspect the amperage using DCC would be close. The transformer used is a ZW-L, output voltage reading of 17V at the transformer. The amperage is as displayed on the ZW-L ammeters. The track has a max 1% grade so this did not determine the effect of significant grades.  The train is nine American Models Budd cars, two with LED lighting. So it is the weight of 9 cars, the current draw of 7 incandescent illuminated cars.

First up was an ES44Ac Legacy engine, smoke on high. Current draw was 3A, a bit less than I expected.

I did not have a TMCC AM Pacific handy so I used an American Models Northern equipped with TMCC. The amperage was 3.2A.

I then decided to go to the high end of a single engine and used the Big Boy. This is basically an oversize S gauge engine with O gauge motors and electronics. Amperage read 3.4A.

I did not run the train with a double headed AM diesel set. I have one with scale wheels. I know that the current draw of one AM diesel at stall is just under 2A and that one AM diesel will not pull these 9 cars up a 2.5% grade. Base on that I estimate that a double headed AM PA/PA set would draw about 3.6A pulling this train. This suggests a 3A DCC system will run one short passenger train but not a longer one nor will it run two trains. In fact any two of these trains running at the same time would draw a minimum of 6A.

Were it my layout I would get a 10A booster to allow for multi train operation.

You would need a power supply that provides 10 amps - the PS315 isn't it. I think Digitrax only offers 8 amp max boosters.  The amperage comes from the power supply and the booster can handle that much amperage and get to the track.  Depending on your layout size and anticipated concurrent locomotive usage, you might have to split it into power districts. Each power district would have it's own 8 amp booster.  NCE offers a 10 amp system.

Also consider that the PS315 is only 15V.  By the time it goes through the command station/booster, it could be as low as 14V at the track, which will limit the speed.

Brendan

Last edited by Brendan

Are you sure you're limited by power?  If you remove passenger cars does the speed increase?  Adjusting load might give an indication of how close you are to the limit.  The specialty DCC current meter is nice but seems kind of expensive if the net result is a sales guy uses the info to sell you a bigger power supply.

Long shot but is CV5 set to limit max speed?

Stan2004,

I followed your suggestions and timed how long it took for the loco and tender to circle the track loop compared to that for this same unit pulling four passenger cars. Surprisingly, the latter time was only about one second longer; evidently the locomotive is moving as fast as it can.

Upon checking the locomotive speed limit control parameter for the Digitrax DC550 Command Station, I found that it was set at its factory maximum of SP99.

These findings seemingly indicate that I do need to add a power supply booster- -correct? 

@Bob G (WNY) posted:

These findings seemingly indicate that I do need to add a power supply booster- -correct?

Not really.  You have shown that the loco is not being slowed down by the load.  At this point, amperage will not increase speed but voltage will.  Digitrax is aimed at the HO market.  You can power the system with an old laptop power supply.  Many of them are 3A @ 18/19V.  This would put about 18/17V at the track.  If you have one, try it, it won't hurt anything.  I use them to power our club boosters.  The NCE 10 Amp booster power supply is 18V.  Maybe the loco was geared to go slow.  Do you have a video of how slow it is?

Brendan

@Bob G (WNY) posted:

...

I followed your suggestions and timed how long it took for the loco and tender to circle the track loop compared to that for this same unit pulling four passenger cars. Surprisingly, the latter time was only about one second longer; evidently the locomotive is moving as fast as it can.

Upon checking the locomotive speed limit control parameter for the Digitrax DC550 Command Station, I found that it was set at its factory maximum of SP99.

These findings seemingly indicate that I do need to add a power supply booster- -correct?

Have you measured the approximate length of your track loop?  Since you measured the loop travel time at max throttle, this would tell us the scale-speed of your engine.  It's not clear if you're looking to double the speed?  Triple the speed?  For 1/64 S-scale, an engine travels 0.275"/sec per scale-MPH.  So if the engine runs 2.75 inches in 1 second that would be 10 sMPH.  If the engine runs 27.5 inches in 1 second that would be 100 sMPH.

dcs50 ps315

As Brendan above points out, you may be VOLTAGE limited.  From the DCS50/PS315 manual, note how 15V (from you PS315) goes in, you "only" get 12.8V going out to the track.  12.8V would be rocket speed for an N or many HO engines ... I'm not familiar with how fast a typical S engine runs with 12.8V on the track.  While it varies widely, I'd say an unloaded O engine with 12.8V on the track might run 40-50 sMPH.  I'm wildly guessing an unloaded S engine should run, say, 70 sMPH withe 12.8V on the track?  70 sMPH is a good clip so I'm thinking you're not seeing that...but your timed loop measurement will tell us what you're seeing in sMPH.

Do you have a DC power source that is more than 15V?  I'm not familiar with the type of plugs Digitrax uses so there may be some wiring hassle to power your DCS50 with a DC laptop supply or whatever.

From what little I read about Tsumani decoders, they appear to support Analog DC mode.  In other words, you can run the engine in analog mode where the speed is simply proportional to the DC voltage on the track.  It kind of depends on what you have and how much wiring hassle you can tolerate...but what I'm imagining is some way to simply apply some DC voltage to the track and see how fast your engine runs in Analog DC mode.  This would take all the DCC programming 'stuff' out of the equation and tell us whether your engine has the underlying "raw" capability to go your desired speed for a given track voltage.

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I have three of the AM engines Bob is using. Running conventional they reach escape velocity around 15V. I have one converted to TMCC. With about 15V on the track in R100 mode it will pull 6 of the Budd passenger cars faster than is safe for 30"R curves up a 2.5% grade at speed step 75. Something is not right. from the tests I reported above 3A is plenty for one engine and 4 cars. I am thinking the slow speed is something related to the DCC decoder. Any DCC decoder in an AM S gauge engine should be rated for at least 4A. Are we sure the decoder in the engine is not the issue?

I was just re-reading the manual section posted above. I see two issues. The track voltage needs to be at least 15V RMS and the power should be at least 45VA for S gauge engines with passenger cars. For reference, on my S gauge layout each power district is 180VA and there are 8 of them. There is a 14ga feeder every 8' of track and all rail joints are soldered.

Stan2004 asked me to calculate the scale speed of my train as it moves along the short loop of track I'm using for test purposes [see my last post for a related video clip]. It traverses the total 200 inches of track in about 13 seconds- -a speed of 15.4 "/sec. Using 0,275"/sec per actual 1 mph for 1/64 S scale, my train is traveling at 15.4/0.275 = 56 mph. That's a bit slow for my liking; I'd prefer roughly 100 mph at full throttle so that my complete six-car Budd consist can really zip along my planned layout's straightaways.

I contacted Digitrax tech support about my train's speed problem. Their solution is to integrate a DB210 Single 3/5/8 Amp AutoReversing DCC Booster [https://www.digitrax.com/produ...ions-boosters/db210/] and a PS2012E 20 Amp Power Supply 13.8-23VDC [https://www.digitrax.com/produ...er-supplies/ps2012e/] into my existing starter DCC system [Zephyr DCS50 command station and PS315 power supply]. That'll turn out to be a pretty expensive fix [total MSRP = $334]; however, it's quite acceptable to me because the DB210 Booster also provides the means for using at least one- -maybe more?- -reverse track loop[s], a capability I'll eventually need to have for my planned home-and-back passenger terminal/switching layout.

@Bob G (WNY) posted:

Stan2004 asked me to calculate the scale speed of my train as it moves along the short loop of track I'm using for test purposes [see my last post for a related video clip]. It traverses the total 200 inches of track in about 13 seconds- -a speed of 15.4 "/sec. Using 0,275"/sec per actual 1 mph for 1/64 S scale, my train is traveling at 15.4/0.275 = 56 mph. That's a bit slow for my liking; I'd prefer roughly 100 mph at full throttle so that my complete six-car Budd consist can really zip along my planned layout's straightaways.

I contacted Digitrax tech support about my train's speed problem. Their solution is to integrate a DB210 Single 3/5/8 Amp AutoReversing DCC Booster [https://www.digitrax.com/produ...ions-boosters/db210/] and a PS2012E 20 Amp Power Supply 13.8-23VDC [https://www.digitrax.com/produ...er-supplies/ps2012e/] into my existing starter DCC system [Zephyr DCS50 command station and PS315 power supply]. That'll turn out to be a pretty expensive fix [total MSRP = $334]; however, it's quite acceptable to me because the DB210 Booster also provides the means for using at least one- -maybe more?- -reverse track loop[s], a capability I'll eventually need to have for my planned home-and-back passenger terminal/switching layout.

Thanks for posting the video.  It is a little faster than I imagined from your description.  I suggest trying a laptop supply before investing in a booster/PS to verify it will satisfy your need for speed!  They can be had on ebay or amazon for $15-20.  It can remain the PS for your DCS50 if you decide to get the booster.  Power part of the layout  with the DCS50 and the rest from the booster.

Edit:

I took a look at the PS2012E PS manual and noticed it only has three voltage options: 13.8, 16, and 23.  Not sure how much voltage the 23V setting will put on the track - might be worth asking Digitrax.  I am not sure what the maximum voltage is for a AM loco.  The 16V isn't much better than 15.

Brendan

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