Power Supply for Gaugemaster UDS Controller

[Simon G]

I recently acquired a Gaugemaster UDS controller, something I had been after for a while.  It requires 16V AC supplies to both inputs.  I had hoped to use an old laptop power supply for it, but then realised that it is a DC supply rather than an AC one.  Also in my spares box is a 50VA RS transformer with two 12V AC outputs.  First question is whether the 12V would be sufficient to use along with the UDS?  I guess that it might work, but be rather underpowered.

 

An alternative is to connect the two 12V AC outputs in series to give a 24V AC supply.  If I were to do that, what is the best way to reduce the voltage down to 16V?  I have some 10K ohm variable potentiometers, but I guess that while they will provide the necessary voltage, they wouldn’t be able to supply the 1 amp current required for each input to the UDS.

 

Any thoughts on how to do this?.  If I can’t do it with what I already have, I guess that I will just have to bite the bullet and buy a Gaugemaster T1 or M1 transformer to do the job.

[Nigelcliffe]

First thing:   messing with transformers has risks around mains voltages.  Some wiring arrangements can be lethal, leaving mains voltages on unprotected plug pins or wires.  In addition to wiring them safely, you'll need fuses or other cutouts against overload.   Only do things with transformers if you're certain you're wiring is safe. 

 

Assuming first paragraph on safety is understood.   12v AC should work, but output will be lower voltage.  Whether it matters depends on the speed you want your trains to run at - slow speed it will be fine, but if you want to crank things up to full express running, then too slow. 
You can't drop the 24v AC in the way you describe (resistors) and have any useful current out of the system, so forget that. 
You could find an old H&M controller (eg. Duette, etc.), throw away the speed control bits, and just get the 16v AC off the transformer coils. 

 

 

[Simon G]

Thanks for the helpful reply.  I will give the 12V a try and see how it goes.  As the layout is only 8 foot by 4, t is designed more as a shunting and small train layout than a full speed express one.  As it happens, I do possess a H&M Duette, and had considered using the 16V AC supply from that, but as I understand that it is rated at 1 amp, it wouldn’t have been sufficient for both circuits on the Gaugemaster UDS.  I will probably continue to use it for accessories such as powering the CDU for the points.

 

On the safety side, I do intend to fit an overload cutout of some description, probably a resettable fuse or similar.

[Crosland]

6 hours ago, Simon G said:

Any thoughts on how to do this?.  If I can’t do it with what I already have, I guess that I will just have to bite the bullet and buy a Gaugemaster T1 or M1 transformer to do the job.

 

A T1 will be twice the price of the equivalent from somewhere like Rapid Electronics.

[John ks]

9 hours ago, Simon G said:

 Also in my spares box is a 50VA RS transformer with two 12V AC outputs

Should be OK provided you follow all safety requirements

John

 

[kevinlms]

8 hours ago, Simon G said:

Thanks for the helpful reply.  I will give the 12V a try and see how it goes.  As the layout is only 8 foot by 4, t is designed more as a shunting and small train layout than a full speed express one.  As it happens, I do possess a H&M Duette, and had considered using the 16V AC supply from that, but as I understand that it is rated at 1 amp, it wouldn’t have been sufficient for both circuits on the Gaugemaster UDS.  I will probably continue to use it for accessories such as powering the CDU for the points.

 

On the safety side, I do intend to fit an overload cutout of some description, probably a resettable fuse or similar.

Don't use the single 16V Duette supply to power 2 controllers, that will lead to potential (sorry!) problems. You want two independent supplies.

 

Given your small layout the 2 x 12 Volts will probably be fine. Make sure you wire the 240 volt side safely.

[Simon G]

The 240V part of the transformer is already wired up, and located in a metal RS box, with the box connected to the mains earth, so is pretty safe already.  It is currently fitted with a 13 amp fuse, so that will be replaced with a 3 amp one.   I will wire up each of the 12V sides with some inline 2 amp fuses that I already have.  Given today’s grotty weather, I will get this all done today with a bit of luck!

[Nigelcliffe]

7 hours ago, kevinlms said:

Don't use the single 16V Duette supply to power 2 controllers, that will lead to potential (sorry!) problems. You want two independent supplies.

 

 

Agreed.  My idea was to open the Duette and use the two transformer windings inside to give two independent AC outputs. 

 

But, apart from reduced top speed, the 12v transformers sounds a promising approach. 

 

- Nigel 

Edited July 28, 2020 by Nigelcliffe

[Simon G]

As intended, I got it all wired up yesterday, and tested on a 1 metre length of track (as my layout isn’t yet properly functional).  With the 12V transformer, I got about 9V to the track, as you might expect.  When tested with a Bachmann pannier tank and the UDS controller, it took the loco about 5 seconds to cover the 1 metre on full power, as opposed to about 3 seconds on full power from a Duette.  I now need to build the UDS into my layout to see if it does provide sufficient power for planned working.

[Simon G]

On 28/07/2020 at 08:38, Nigelcliffe said:

 

Agreed.  My idea was to open the Duette and use the two transformer windings inside to give two independent AC outputs. 

 

Do you happen to know what is inside the Duette in terms of transformers?  Mine has remained unopened since it was made.  It obviously has the two track controllers, along with the 16V AC and 12V DC outputs on the sides.  I don’t plan to open mine up, but may have access to a second one, which I would be prepared to use as you suggest, if the 12V transformer doesn’t come up to scratch on the layout.

[Nigelcliffe]

1 hour ago, Simon G said:

 

Do you happen to know what is inside the Duette in terms of transformers?  Mine has remained unopened since it was made.  It obviously has the two track controllers, along with the 16V AC and 12V DC outputs on the sides.  I don’t plan to open mine up, but may have access to a second one, which I would be prepared to use as you suggest, if the 12V transformer doesn’t come up to scratch on the layout.

 

There are pictures here

 

Essentially, a single transformer, with two windings (very common arrangement, which is what the Gaugemaster T1 would be).  Thus, two independent 16v AC outputs from the transformer.    If chopping a Duette up, I'd remove the front control knobs, all the controller mats and the DC rectifier,  blank over the rear and side connections, and replace (or fill) the front panel.   Fit suitable sockets (could re-use the Duette side socket if happy with banana plugs) to the front panel labelled as the two AC outputs.  

 

Only do the above if you're confident about electrical safety - there's mains involved, and transformers wired wrongly can be extremely dangerous.