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Discussion Starter #1
I have been trying to help a friend out with a Digitrax system for quite some time, and have several of his loco's converted to DCC. He has a DCS 200 that he purchased to run HO and Large Scale, he has now decided to go with Large Scale only. He is now thinking he is short on power. Looking at the label on the DCS it states MAX input 8A 12VDC 96VA or 28VDC. His power supply puts out 23VDC. SOOO is the DCS limited to 96VA? At 23 volts that would be just over 4 amps. Not much to run his three large loops. I am sure he could start adding boosters, but now I would like to know the limit on his DCS200. I could get him to convert to NCE or Massoth if he could recover his cost in the equipment he now has.
 

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Super Modulator
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1. I think you have some missing data, the input cannot be 12VDC or 28VDC... I'm guessing you have the input right, but missed the word "output" before the 96VS or 28VDC, but that does not make sense either. Take a look again.

2. VA as an output is NEVER a rating that works at all combinations of output voltage and current. That's why they use VA instead, makes the numbers look better. Long explanation, but take my word for it. You need specs on max output current at max voltage.

3. You always lose about 3 volts minimum from input to output of booster. 23VDC should top out at about 20V to the rails.

Regards, Greg
 

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Max output voltage 20 volts, max current 8 amps, 80 VA... with the proviso that conditions can limit the output.

Often Digitrax cannot output full amps at full volts.

Should be fine, just have a power supply at 23 volts or higher, up to 28volts DC input. It may be that they USED to rate the output at 96VA, but it's not true.


He should be fine up to 6 amps for sure, above that, many people have reported that it cannot achieve full rated output, so he may not get 8 amps.

Have him put an ampmeter on the input side and see how much current he is drawing.

Regards, Greg
 

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Discussion Starter #5
When it warms up here in the Midwest we will have to play with it a while. He has a USA ABA and 6 of their passenger cars. I took the motors out of the B unit and it pulls the cars on his level loops easily. The problem will be he has 2 other loops. Easy to run 3 trains if we come up with enough power. Thanks.
 

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I have a DCS200 and it has an output capability of just over 8 amps with 21 VDC input. I run that one at 18 volts on the rails at no load. At the highest loads, the rail voltage sags.

I have a much older DCS100 that is also an "8 amp" version, but it will output only 7 amps, but at 22 no load volts on the rails. At higher loads, the rail voltage sags significantly. While I was actually using it as a booster this one ran from a 22 VAC 15 amp transformer. Now, I use it only as a command station and to run the programming track so it runs from the AC output of a Bachmann power pack and it does fine. The big transformer runs an NCE PB110 booster that actually drives the rails at 22 volts and it maintains nearly 22 volts at 10 amps. It does not trip until it reaches 20 amps.

The older DCS100 would run two trains with lighted cars, but it could not handle a 3rd train of any size. The PB110 drives 3 heavy trains without sweating. I don't have enough concentration to run more than 3 trains at once so I haven't actually tried it with more.

BTW, for DC, watts are identically equal to VA. VA only makes sense in the context of AC power where a reactive load can shift the phase of the current with respect to the voltage. In that case, VA is the product of the voltage and current, ignoring the phase shift This is called reactive power and is important in sizing wiring, transformers and circuit breakers. Watts is the REAL power delivered to the load considering the phase shift and is ALWAYS less than VA.
 

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George, I know what you are saying about VA, and I'm sure you are technically correct.

But I have seen time after time a VA rating on the output / DC side, and the pack would not put out the same VA at all voltage/current combinations. Buy a MRC 6200, and try to get it's VA rating at top voltage, you cannot.

I think manufacturers are abusing this rating.

Regards, Greg
 
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