Troller TRA 1001

[Edgar]

This troller transformer came with a LGB 2028D Mogul I bought last fall. I believe the couple I got it from bought them together in the late 1980’s. A sticker on the back of the transformer states it was modified Kurtz-Kraft to be equivalent to their ‘TH-3 throttle.’ Is anyone familiar with this equipment and is it safe for LGB?

 

[dunnyrail]

Chances are it will probably be fine, safe for LGB is probably not the right ask as it is unlikely that an overload by LGB would blow this up. Note the overload red button, this would pop up if too much current were being drawn by the Mogul.

 

[Edgar]

Jon, I have seen several discussions here mentioning LGB engines not liking pulse current and don’t know what this transformer is. My son likes the momentum future. The previous owner used it for many years at Christmas. I wonder if this might be a reason for the sound not working on the mogul.

 

[Greg Elmassian]

Yes what edgar said, for many years pulse power was a cause for invalidating the LGB warranty, they claimed it would damage the motors.

A very reasonable question considering the history of LGB, and an older power pack.

In modern days, it appears that the LGB mandate about pulse power was balderdash.

Use it, run the loco for a while and then check the temperature of the motor with your finger. If it is over 160 degrees F then you will not be able to keep your finger on it.

Greg

 

[Gizzy]

Not seen one of these before, but I suspect it is PWM rather than smoothed DC....

 

[Greg Elmassian]

Maybe, pretty old, might be one of the old Triac circuits too...

Greg

 

[dutchelm]

The reason LGB do not like PWM was not due to problems with motors but the PCW spikes wrecked the electronics. Kiss of death to sound units & decoders.

 

[Greg Elmassian]

What are PCW spikes? Was that to be PWM?

Greg

 

[dutchelm]

What are PCW spikes? Was that to be PWM?

Greg

Yes, computer doesn't spell very well. Had to put in decoder 3 times before it stopped changing it.

 

[Tony Walsham]

I think you will find that to get slow starts etc the makers injected a bit of AC over the controlled DC voltage.
Early form of "Pulse" control.
Not the same as pwm.

 

[Edgar]

The transformer doesn’t adversely affect the operating temperature of the engine. Years ago I bought a MRC Power G for double engine operations; my son just likes using this antique. Does anyone know, or have a guess, what the expand/normal switch is for.

 

[Dan]

To me the tra1001 is not even enough power as LGB uses 24 volt motors on all their engines. Sure steam locos were slow, but many needed more than 12 volts with the internal electronics, esp. the newer engines with decoders.

 

[Greg Elmassian]

And if you research that model, you will find it has a history of failures an unreliability.

I'd believe it will be safe for your trains.... but it might not even be UL approved, perhaps not safe for you or your house.

Greg

 

[PhilP]

The transformer doesn’t adversely affect the operating temperature of the engine. Years ago I bought a MRC Power G for double engine operations; my son just likes using this antique. Does anyone know, or have a guess, what the expand/normal switch is for.

I will make two guesses on this: - But they are guesses!

1. Reduce the overall-voltage, so giving an 'expanded-range' of control (all-be-it, at a lower speed) - for finer control when shunting, perhaps?

2. Two different PWM frequencies. - Some early models had motors which much preferred a lower-frequency.


Though, as I say, these are guesses..

PhilP.

 

[Edgar]

Last year I read what little could be found about it and wrote it off as a $20 piece of junk. My son pulled it back out, wanting to test it, and likes the momentum feature. I couldn’t care less about momentum; I like watching a slow circuit. I’m curious if the transformer where gutted, would the pots be stout enough to control the current off a Dell laptop supply.

 

[PhilP]

I’m curious if the transformer where gutted, would the pots be stout enough to control the current off a Dell laptop supply.

NO!

There is more to control, than just putting a pot. across the supply, and using the wiper to 'tap-off' a varying voltage.

Unless this controller uses substantial wire-wound pots. for the controls (which I doubt as it has 'momentum' etc.) then they will probably only have a 0.3-0.5 watt rating.

PhilP.

 

[Edgar]

NO!

There is more to control

Phil, the back of this controller says it has 60VA. Does this equate to less than one amp of power that I might understand? My LGB 5003/110 will not run the Mogul and a consist of lighted cars, but this troller will.

 

[Edgar]

Phil, can you tell anything about the pots from this photo?

 

[PhilP]

Edgar,
They are 'standard' pots. for the vintage of the controller..

The large transistor (bolted to the metal plate, by the transformer) is what controls the output.. - The pots. give a small control-signal to make the big transistor alter the output voltage.

The 'VA' rating is (this is a simplified 'lie to children') equivalent to the amount of 'power' the unit consumes. - Roughly 60 Watts..
If (to make the maths. easy) we assume the unit is 100% efficient:
If you are only taking power from the variable output, and this is at 12V. then you can draw (theoretically, remember) 5 Amps.

12 Volts X 5 Amps = 60 Watts.


From what I can see of the 'innards' of this unit, there is nothing that suggests it is more than a perfectly adequate 'Old-School' linear controller..
It might get a little warm, but I would expect you could draw 3.5-4 Amps from it, for the length of a running session, with no problems.
So will run your two-motor loco, etc. without a problem.

I would quite expect it to continue to operate for many years, but could fail tomorrow. - As most electrical units!
Check the state of the power-cord, and plug, especially if the plug is rewireable (are the connection screws inside still tight?). Is the cord frayed, or floppy, where it enters the unit. - Stress here can break the individual strands of wire.
Looks like a two-core power-cord? - So the metal case is not earthed. This would be frowned-on, today. But hey! If you touch it, and get a 'rattle', then it is time to bin-it!


Enjoy it (and the trains) with your Son, and mentally put yourselves in an early 'Father and Son together' train advert.
Enjoy!
PhilP.

 

[Greg Elmassian]

I have to underscore everything Phil said, very well detailed response. I'll bet the transistor says 2n3055 too...

Run it until it fails and throw away.

On further refinement on VA:

60 VA means that SOME combination of output voltage and amperage gives you 60 VA.

To be very precisely clear, there is some point where if you measure under load, the output voltage and multiply it times the amperage in the circuit under load you get 60.

BUT normally it is NOT at max voltage, so if the unit is listed as 60 VA and 12 volts max (note maximum, not regulated), then it is NOT implied that at 12 volts you get 5 amps.

It is a trick of making the rating of the system look "larger" / "better" than it actually is.

In the US, most manufacturers have stopped using this rating, but it's still around.

You asked about changing the power supply, I assume to get a higher voltage. You would need to study the power rating of the output transistor, and also take a whack at the heat sinking ability of the case, as without a heat sink the transistor will burn up.

The case is not a great heat sink, as it does dissipate as well as a multi-finned heat sink, painted black to help radiation.

Bottom line, I would not use it as it until it quits and then throw away. You can get inexpensive controllers for just a few bucks on ebay, hook to a 5 amp 24 volt laptop supply and have a great and inexpensive PWM controller.

Greg