# NCE PH-pro and LGB 50111 power supply



## itsmcgee (Jan 4, 2008)

After reading many forums I decided to buy a NEC PH-pro 5 amp starter set. (should be here in a day or two.) I was reading the downloaded instruction book about power supplies. I intended to use my LGB 50111 power supply. The instructions say do not exceed 18 VAC. When I meter the LGB output it measures 18.34 volts. Will this in fact smoke the system?


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## mbendebba (Jan 22, 2011)

mcgee: I seriously doubt it would. I think you are referring to an older 50111 which is rated at 18V; the newer ones are rated at 20V. 

Mohammed


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## itsmcgee (Jan 4, 2008)

Thanks for your response; it is one of the old 18 volt ones


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## Cougar Rock Rail (Jan 2, 2008)

It seems very odd that the NCE wouldn't accept more than 18V, since that doesn't even come close to meeting NMRA DCC standards for large scale. As Mohammed says, though you should be fine if the supply is only putting out 18V. 

Keith


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## Greg Elmassian (Jan 3, 2008)

That's because it will also handle 28 volts DC, a much wiser way to power since you can get a regulated dc supply 

Greg


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## Cougar Rock Rail (Jan 2, 2008)

Sorry, you lost me Greg...why would DC be any better? With LGB or Massoth you can use either AC or DC. Using my LGB 50111 transformer I get about 22.5 volts at the track, would it be different if I powered the central station with 24V DC? 

Keith


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## krs (Feb 29, 2008)

Let me jump in here Keith, 

First of all - 
the maximum 18 volts AC recommended is the rms value, that is equivalent to a peak value of 25.45 volts and after one rectifies it and smooths it, one will get a DC value of around 24 volts depending on the devices used for that function. So generating the maximum NMRA DCC signal of 22 VDCC using that power supply is not a problem. 
Trouble with an AC supply like that is that it's typically not regulated, so if the output is 18 volts AC at say 115 VAC line voltage, the output wil rise to over 19.5 volts if the line voltage goes up to 125 VAC say. 
Greg mentioned a *regulated* DC supply - that would provide a constant DC voltage to the NCE unit regardless of line or load fluctuations and thus the DCC voltage the NCE generated would be constant. 

Knut


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## Cougar Rock Rail (Jan 2, 2008)

That's very interesting, thanks Knut! 

Keith


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## krs (Feb 29, 2008)

Now you lost me - what is "very interesting"?


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## Axel Tillmann (Jan 10, 2008)

Besides the reasons that Knut gives, there are some other practical reasons for a straight regulated DC power supply:

1. AC power supplies are bascially transformers and a power unit based on this is more expensive than today's regulated DC power supplies.
2. Most DCC system have poor or no stabalization, therfore the amplitude moves with the current draw. The higher the current the lower the output voltage. To my knowledge ZIMO was the only supplier that had a fully high end regulated DCC output which stayed at x Volt if you adjusted the output voltage to be X. There was a cost associated to this - of course, you had to lower the maximum track voltage to the sustainable input voltage otherwise the system signaled over current draw. (example Input 24V but voltage could drop in unregulated state to 18V you would have to adjust to 18V and you never saw the higher voltage and never lower either.


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## Greg Elmassian (Jan 3, 2008)

I did notice that the Zimo output was regulated, a nice feature not shared by many units. 

Most systems, in my experience, drive the output voltage from the input voltage, no regulation. 

Many people do not know that an AC transformer, even high quality ones, will drop 10% at full load. Most of what we get to buy drop 20% or more. 

I found early on that to get adequate top speed from some of my locos, I really needed as close to 24 volts on the track. Now, if your voltage can drop 20% under load, then the unloaded track voltage will be 20% higher if you use an unregulated supply. 

So, if you did this with an ordinary AC transformer and DCC system, your unloaded track voltage would be 28.8 volts... 

Now you are over the NMRA spec, and I will guarantee you will be burning out lights and finding weird stuff with your decoders in many cases, not to mention the difference in performance between light and heavy loads on your system. 

So, a regulated output to the track is my desire... everything runs better and more consistently. 

There's how I progressed. So, I will only purchase systems that either allow DC input (like the NCE), or have a true regulated output (like the Zimo). 

Regards, Greg


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## mbendebba (Jan 22, 2011)

Masssoth has always offered an adjustable, and regualted, stabilized track voltage (14-22V) along with an adjustable maximum track current (4, 7, 12Amps for the 1210z, and 2, 4, 8Amps for the 800z). 

Mohammed


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## Cougar Rock Rail (Jan 2, 2008)

Now you lost me - what is "very interesting"? 

a) I find it interesting that the 18V is RMS and that equals a peak of 25.45V and 
b) That when the line voltage changes the output changes--I had assumed all of these products would be regulated, but apparently not. 

Thanks, 
Keith


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## Greg Elmassian (Jan 3, 2008)

No, most US systems are not regulated. 

Mohammed, what is the maximum allowable input voltage on the Massoth, and does it do AC and DC (I thought AC only) 

Good to know another system that regulates the output. 

Greg


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## Cougar Rock Rail (Jan 2, 2008)

Greg my MTSIII (ie built by Massoth too) will take either AC or DC, and since my AC transformer (50111) is 20V per Knut's explanation it can take at least 24V DC.


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## mbendebba (Jan 22, 2011)

Greg: both central stations accept AC (12-18V) and DC (16-24V). I have , a couple of times, un-intentionally supplied up to 22V AC and 27V DC. 

Mohammed


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