# Will this transformer be enough?



## shadowvfx (May 3, 2010)

Hey everyone. I was going to set up a ceiling train layout at my house. My father and I have lots of trains at his location, including a beefy transformer for running them. However, I was wondering if I could use this LGB transformer for running my USA Trains gp-30? Here's a pic of the transformer I'm using and a link to the engine. It won't be pulling more than four or five cars, and the track run won't be more than 40 feet in length. Will this work, or do I absolutely need to buy a larger transformer to run this engine? 

http://www.usatrains.com/usatrainslocogp30.html


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## chuck n (Jan 2, 2008)

Your engine has two motors. That unit is for a single motor engine. There is a very good chance that the power supply will over heat and shut down. Then when it cools down it will reset. If this happens you will have to get a more powerful unit.

Chuck


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## Greg Elmassian (Jan 3, 2008)

At absolute best case that transformer would put out 1/3 amp at higher voltages.

USAT you should figure around 2 amps per loco. 

So, you are basically underpowered by about a factor of 6.

So, it probably would have trouble even at very low speeds.

Greg


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## shadowvfx (May 3, 2010)

Alright, so the transformer won't cut it for this engine. Does anyone have recommendations on brands I could look at that would be cheap but provide enough power?

I see that LGB sells a 6 amp I could get one on eBay or on some online stores for ~$160, but I was really hoping I could find something for ~$70 or less that would suffice.


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## Greg Elmassian (Jan 3, 2008)

No, unfortunately I do not have recommendations for cheap products to run a locomotive that is pretty high current compared to other locos.

Look for a good deal on a used one I guess.

Not trying to give you a hard time, but a good transformer with a good current rating is NOT cheap. That's just life.

The most known brand is probably MRC, but their quality control on the lower cost products is iffy, I just saw a post where someone just bought a 9900 and it was DOA.

I'd probably look for a controller that could handle 5 amps and get a separate 5 amp supply.

You could probably find an electronics kit with a motor controller and build something.


Greg


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## shadowvfx (May 3, 2010)

Thanks for the info. I had heard that USA train locos were less efficient than LGB, but I had no idea it was so much of a difference.


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## Greg Elmassian (Jan 3, 2008)

Scroll down to the chart, and read the current on the USA trains locos, although this is some worst case stuff.

http://girr.org/girr/tips/tips4/tractive_effort_tests.html


Greg


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## ntpntpntp (Jan 14, 2008)

shadowvfx said:


> Thanks for the info. I had heard that USA train locos were less efficient than LGB, but I had no idea it was so much of a difference.


 To be fair, that LGB power pack at 1/3 amp would struggle with any LGB 2-motor loco, and even something like a Mogul would slow on corners. It's just a starter-set power pack intended for a small loco.


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## Greg Elmassian (Jan 3, 2008)

I would have said something like that, but every time I do, someone will come up and say how they run 2 LGB locos with 8 cars on that transformer. 

Personally having a transformer under 3 amps seems absurd to me, but I know people do it. Running a transformer near it's capacity is not the way I run electronics.

Greg


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## Don T (Dec 28, 2014)

IN one of the older LGB Catalogs it shows that controll at .5 Amps. However, I'm one of those who 
got away with using it for several years on a fairly large floor layout in my basement with single motor 
engines.

Don T 


Don T


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## Garratt (Sep 15, 2012)

I think as a rule of thumb 1 amp per motor will work for light duty as a minimum on a small extended layout. Not trying to be argumentative just as a possible minimum. 
Some people can't lash out on large power supplies to do the job with more than adequate power.
A 2 amp controller will probably work fine but as Greg indicated that may be running near full capacity if cranked up which is not ideal for prolonged use. There are other considerations like lighting, sound and smoke too.

Andrew


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## Garratt (Sep 15, 2012)

Don T said:


> IN one of the older LGB Catalogs it shows that controll at .5 Amps. However, I'm one of those who
> got away with using it for several years on a fairly large floor layout in my basement with single motor
> engines.
> 
> ...


I used to mainly have small engines on a small layout with a similar controller. Anything I bought later would run even 2 motored diesels. I then bought a Brawa consolidation with upgraded Maxon motor. It just sat there completely motionless with a slight hum. 

Andrew


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## Greg Elmassian (Jan 3, 2008)

I think a lot of them are run at or above the rated output. I've heard many people comment (just before the units give up) that they were running pretty warm.

One reason I went into the spiel about trying to get away with an underpowered transformer is not to contradict people who have done it, but to give good advice to a newcomer.

Sure it might work for a bit, but it might also not work or just melt the transformer housing. Such advice is NOT what I will give out.

Seasoned individuals, or those who know the risk of destroying the transformer and are fine with the risk, that's their right to do so.

But I try to give GOOD advice, not marginal, or it MAY work. Newcomers are to be helped and to a certain degree protected from bad experiences.

OK, getting off the soap box 

Greg


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## shadowvfx (May 3, 2010)

Can I ask ow you guys got the 1/3 or .5 amp output on my LGB transformer? I'm not an expert on electronics, but I don't see it listed on my controller. Did you do some math using the numbers shown to get that output?

I'm curious because if I'm looking for a transformer that will do the job, I'd like to make sure it's adequate. Most controllers I see have a number listed as XX VA. I assume that means Volt Amps?

Not saying I'm going to get this, but here's an example of what I'm looking at and trying to figure out its amp output: https://seattle.craigslist.org/tac/tag/5339665368.html


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## Greg Elmassian (Jan 3, 2008)

Easy, your picture of the transformer.

It says 0-21 volts, 7VA... so the MAXIMUM THEORETICAL (which never happens) current on that transformer at 21 volts is 7/21, or 1/3 amp.

VA= volts times amps. (but not at all combinations of volts and amps, this is key)

so if you have 7 VA and 21 volts max, then

VA = 7

substitute 21 for V(olts)

21 A = 7

Solving for A(mps)

A = 7/21 

A = 1/3 amp.

So even at the theoretical maximum (again which never happens) at 21 volts output you could only have 0.33 amps.

At half voltage 10.5 volts, you could only theoretically have 0.66 amps.

Greg


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## Don T (Dec 28, 2014)

The 1990/1991 World of LGB Catalog lists the 5003 Controller as---

Output 0-18V DC at 0.5A

Output for lights/switches 14V at 0.5A

Total Output 16VA


Don T


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## Greg Elmassian (Jan 3, 2008)

Notice they do not say 1/2 amp AT 21 volts?

max voltage, VA, and at SOME setting it does 1/2 amp.

Is this getting through? You can play games with specifications, you have to pay close attention.

Greg


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## Garratt (Sep 15, 2012)

As I understand it they will cherry pick the specs from the range of voltages to get the highest VA rating they can for marketing reasons. What you get at the voltage you require is another story. As a guess, at full throttle the amp rating would most likely be less than what you would equate from simple VA math. 

The MRC TrainPower 6200 rated at 60 VA could possibly give you 3 amps at 20 volts, just depends on what voltage they tested it. Having said that, it would probably be a reasonable match for your 2 motored diesel to haul 4~5 cars as originally asked.

Just for the OP to understand it is higher voltage that makes the train go faster as long as the amps needed are being provided by the controller. Adding more cars, going up a hill, using smoke, lights and sound will all draw more amps. If the train tries to draw more amps than the controller can deliver, then the controller is working beyond it's ideal range and will overheat, cut out, blow up, have a thermal meltdown, whatever... I'll let you pipe in on that Greg after all I'm no expert I just try to avoid letting the smoke get out of the wire. 

Andrew


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## Greg Elmassian (Jan 3, 2008)

Pretty much right Andrew, and in this case I did own a 6200 and at full voltage it was UNDER 2 amps, not enough to run both motors on an LGB track cleaning loco.

I gave my 6200 away to someone who runs slow and light loads.. 

I got very disenchanted with any power supply that does not spec volts and amps at full load. Clearly unloaded the voltage will never be an issue. When I see VA only ratings then I just walk away most times.

Greg


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## Garratt (Sep 15, 2012)

Don T said:


> The 1990/1991 World of LGB Catalog lists the 5003 Controller as---
> 
> Output 0-18V DC at 0.5A
> Output for lights/switches 14V at 0.5A
> ...


On the back of the controller itself is is marked:
Output I, 0~21 VDC 7VA
Output II, 16 VAC 7VA
Total output 14 VA

So at 14 VDC it could very well be more like 0.5 amps. LGB controllers are quality products made in Germany by Buhler, Steger and Siemens who perhaps are more conservative when specifying VA.
In any case that controller is only good for a small 0-4-0 hauling 3 short cars around a loop like what comes in a starter set. Those controllers are outgrown quickly. 

Andrew


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## Greg Elmassian (Jan 3, 2008)

I'm pretty sure that you are right about conservative ratings, based on the experiences of people who have run more than one loco from the pack, and also those who have reported running the unit under enough load that it got "hot". It had to be pulling near an amp with 2 locos my guess.

Regards, Greg


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## shadowvfx (May 3, 2010)

Hi everyone. It's the OP again. I've been watching my local Craigslist and saw this for sale. I told the seller that I needed something that is a min of 2 amps and could run a USA trains Loco and he said that this unit could. He is selling them for $25. However, even if it's cheap, I thought I'd check here first to see if anyone has feedback. I don't have the exact stats of this unit, only what is visible in the photos. Do you think this would run my USA Trains deisle with 5 cars? Anyone heard of this brand or have any thoughts about this unit? 

Thanks so much for all of your help and input. 

https://seattle.craigslist.org/see/ele/5399402214.html


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## JerryB (Jan 2, 2008)

Various internet sites show pretty poor performance form the Star-Tec units. Several reports of low output, component failures and unavailability of schematics or replacements.

For a local report, see this MLS link:

starr tec hogger 100mw shematic or modifications?

Some folks on other sites report something like 2 or 3A at 5 or 10V. Really not enough power even for H0!

Happy RRing,

Jerry


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## shadowvfx (May 3, 2010)

Yeah, I saw that thread too. I was just hopeful that at $25 for BOTH units that it wouldn't be a big risk to buy it and see if it works. If not, then I'm out $25 (not a huge hit), but if it DID work, then I got what I needed at a very cheap price.

I suppose I'll sit and think about it a bit. Thanks for the thoughts.


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