I am used to working with Loksound decoders and their terrific BEMF and start voltage sensing. Recently I purchased both Digitrax and NCE decoders to go in my other engines. So far, I can't get any of them set to run smoothly at slow speeds, or even get a decent slow start out of any of them. The packages on the NCE state their decoders have torque compensation for smooth low speed running. What am I missing here? My Loksound equipped engine will literally crawl from tie to tie at the exact same speed on step 1, regardless of incline or load.
I'm using Decoder Pro for programming. The Digitrax and NCE decoders are placed in P2K's and remotored Athearn engines. My control system is NCE.
The Cedar Branch & Western--The Hillbilly Line!
The NCE tourque compensation is adjustable by CV116 and 117. Most decoders like the Loksound are automatic and need no adjustment. I can not help you with the Digitrax decoder settings. You can adjust these CVs until you get the slow speed running you want. I dont know it decoder pro can help but programing on the main is faster than program track mode.
Hope this helps
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Thanks, Pete. I agree with the main programming! That's much faster.
I tried following the NCE package recommendation of tweaking the starting voltage until it is just below the engine's ability to stay in motion, then manipulating the kick frequency and strength. I've not tried this using just the two CV's. I'll play with them some more after church today.
Back-EMF actually reads ther voltage generated by the spinning motor in between pulses of power being sent to it to determine if it is turning at the rate it is being told to turn. Depending on the settings configured, this can be set so that NOTHING will stop the motor from turning short of actually clamping the shaft. Go up a hill, more power is applied to keep it turning at the same speed. Add a dozen cars, more pwoer is added. Go down hill, and power is removed to keep it from speeding up. ESU decoders have this - and they do it very well, as do the other European decoders like Zimo and CT Elektronik. It seems in Europe they are more concerned with maintaining set speeds with no additional throttle control, and so have perfected the BEMF response. Digitrax has BEMF in their 16x decoders, the 12x don't. It works but not nearly as well as ESU's. TCS has BEMF in their decoders and it seems to work very well in my initial test track testing. QSI has BEMF in their sound decoders which works very well.
NCE does not have BEMF in their decoders. Torque Compensation is not the same thing, nor is it a repalcement - it's more of a complimentary feature. When controlling a motor with high frequency pulses (silent drive, supersonic, silent running - each manufacturer calls it something different), the tradeoff for less motor heating and no buzzing noises is less total power, thus less torque, precisely when you need it most - at the lowest throttle positions. Torque compensation applies extra power at low speeds to overcome this. This is usually configurable in decoders that have it - too much and your loco might leap into action, too little and you might still need to advance the throttle more to get it to move but then throttle it back to the actual sustained lowest speed.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy, that was very informative. Thanks! In short, is sounds (no pun!) like I should gather all of these Digitrax and NCE decoders and put them on ebay. From here on I'm sticking with Loksound and possibly QSI. I guess you truly get what you pay for!
By the way, Loksound does have a feature which allows the constant speed control taper off as the speed and load picks up.
ESU also makes Lokpilot, non-sound decoders.
TCS decoders with the back-EMF work good as well. Might be easier to get, made in USA. http://www.tcsdcc.com/pdf/BEMF.pdf
I have a Digtrax DH165LO in a P2K GP30. With a few adjustments, I got it to run decent with a TCS in the other P2K GP30. These have back-EMF, with all sorts of adjustments. http://digitrax.com/appnote_bemf.php
The TCS run good right out of the box.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
I've used a bunch of the NCE decoders, particularly the D13SRJ because they are like $12 each - very economical if you have a large fleet to convert. In decent locos like P2K and Stewart they run just fine - BEMF is nice but I don't think I NEED it. It's much more critical when automating operation, to make sure unattended trains don't stall on hills, or fail to start.