TIU Aux power supply

Jim,

How can it be AC or DC? 

AC is interanlly rectified to DC inside the TIU.

If it's an isolated supply, like perhaps an old laptop supply, you can use anything you have from 12 to 22 volts and 1.5A or more.  I have several laptop supplies that put out 18-20 volts as 3-4 amps, they're perfect for the task.

Note that the center pin of the aux power and the outside rail connection for Fixed #1 are common, so that's why I mention the isolated part of the aux power supply.

5.5mm 2.1mm barrel connector.  You can get a 12V DC, 2 Amp (12V x 2A = 24 Watts...just like the elusive MTH 50-240) wall-wart for about $2 on eBay free shipping from Asia.  If you see the words "for CCTV" or "for LED" in the eBay listing that will have the correct connector (though I'm sure there are oddball exceptions).  As long as it's a plug-in-the-wall adapter or wall-wart, it will be electrically "isolated" hence doesn't matter what the polarity of center pin is.  On eBay be sure you get one with a "US Plug" assuming you're in the US of course.

Thanks all,

I will rummage through the box of stuff I have been keeping for just this occasion. 

If NG, I will source out a used laptop power source for the "right price"...

-Jim

If you will not be having many AIU relays pulled in at the same time, you can get away with a wallwart of lesser amperage. 

RJR posted:

If you will not be having many AIU relays pulled in at the same time, you can get away with a wallwart of lesser amperage. 

Given the $2-3 price for a power brick with plenty of power, why bother using a marginal power source?

By rummaging through the unused valuable items junque box, one can save $2-3

Didn't find a suitable wall wart in the box..

Came across a Dell laptop power supply and soldered on a 5.5 x 2.1 barrel plug.

Power supply - free

Barrel plug - $1.29

14V DC @ 4 amps - Cool

Thanks all.

gunrunnerjohn posted:

Note that the center pin of the aux power and the outside rail connection for Fixed #1 are common, so that's why I mention the isolated part of the aux power supply.

John,

To clarify, the power supply I came across is center pin positive. 

Using this for the TIU Aux power, it is isolated, correct? (no other connection to common).

Therefore, the polarity on the center pin does not matter, correct?

Thanks,

Jim

Jim,

Using this for the TIU Aux power, it is isolated, correct? (no other connection to common).

Correct.

Therefore, the polarity on the center pin does not matter, correct?

Correct.

Thanks

My aux supply is center pin positive, the trains never noticed.