TIU Power

From the DCS O Gauge Companion 2nd Edition, page 93:

TIU Aux. Power Sources

There are several sources of power that may be used to power the TIU through the Aux. Power port. In general, any AC or DC power supply that provides 1.5 amp of power at a voltage between 12 and 22 volts and has a suitable connector that fits the Aux. Power port will work.

One source of power for the TIU's Aux. Power port is any one of the smaller MTH transformers, such as the Z500, Z750 or Z1000. Their barrel plugs exactly fit the TIU's Aux. Power port. If using one of these transformers, it is important not to use the Z-Controller that may be included with the transformer.

Another source of power for the TIU's Aux. Power port is the Radio Shack "#273-331 "Enercell™ Switchable 18/24VAC 1 AMP Power Adapter with #273-344 Enercell™ Adaptaplug™ M. It should be used on the 18 volt setting.

A third source of power for the TIU's Aux. Power port is the 14 volt output of an MTH Z4000 transformer using an appropriate barrel connector. It should be noted that if the Z4000's 14 volt output is used, it should be used solely for this purpose and not used to power any other device.

This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!

FWIW

I found a couple of Z500 transformers at good prices and use them.  They already have the proper barrel jack thingy and are the appropriate power rating, etc.. 

MTH also has announced a wall wart for this purpose, which appears reasonably proced.  I saw it on the Trainworld web site at a discount.

NS,

   I use the RS 18/24 Power supply it works great and most time you can pick them up used on the internet for about 1/2 cost, I have a couple of them for each of my TIU's. 

Have used them for a very long time and they have not gone bad.  As Barry points out use the 18 setting for powering the TIU.

PCRR/Dave