I am FINALLY expanding my layout and will be adding 2 O-42 turn-outs and possibly one more operating Realtrax turnout. All of these turn-outs will be on my main-line. The 2 O-42 turnouts will create 2 an inner and outer loop, the other turn-out will be used for a spur/stub siding. No accessories were previously powered via the track nor will they be on my new layout(possibly an insulated section to activate a Banjo signal, but that's it).

My TIU is powered via AUX input and is connected to anl TMCC base using the appropriate cable. I initially plan to only power the layout via a Lionel PH-1 135 watt brick connected to fixed 2 input with fixed 2 output going to a MTH 12 port terminal board.

Here are my questions:

Can I power my Realtrax switches with another, in-phase transformer that is not connected to the TIU? That transformer woud, again, be in-phase and provide the constant voltage the turn-outs requre.

NOTE: I already have an SPDT and know how to connect it to the turn-outs to power them via a separate power source. i Practiced with a temporary conventional straight track, connected the 3 spades from the turn-out remotes to the 3 appropriate terminals on the turn-out, track received power from a ZW. Using another ZW output, I connected a wire to the the SPDT and then connected wires to the 4th terminal, which is meant to receive auxiliary power, on my turn-outs

If it is possible to power the turn-outs with a separate, in-phase transformer, is there anything of which I should be aware or cautious?

If no to the first question, would I need an AIU for remote turn-out operation via a non-TIU connected power source? If that is the case, then I might just go with non-powered turn-outs with auto non0derailing features similar to Lionel O-36 manual turn-outs.

Please let me know if you need any further clarification. Your assistance in this matter is greatly appreciated.




Original Post

I believe the simple answer is yes you can power the switch externally. It’s even recommended, as you don’t want the DCS signal traveling through the switch electronics.  if you simply want to control the switch manually, you then set it up via the switch instructions (included with the switch). It’s as simple as removing a jumper and connecting some wires where the MTH control switch attaches. If you want to control it using DCS, you need an AIU. Instructions are either in the DCS manual, or for more info, you can purchase the DCS companion through the MTH website. 

Thank you @Marty R . Just wanted to verify that I don't need to use a channel from the TIU or an AIU in order to power the switches. I was going through Barry's 3rd edition, which is a great resource as is the TIU owner's manual and the MTH switch manual, but had trouble finding something that addresses where I fall on the spectrum. Layout with...

Conventional Manual switches--Conventional w/ track powered switches---Conventional w/ Aux powered switches---Conventional w/ aux powered Switches connected--DCS user manual switches---DCS user track powered switches----DCS user aux powered switches via power not through TIU or AIU---DCS user aux powered switches via TIU channel w/o AIU ---DCS user manual switches and aux switches controlled via AIU... You get the picture ha.


@StevefromPA you’re welcome. There is no need to waste a TIU output on powering switches. I think that’s the important takeaway. The other important takeaway is that sending track power through switches can be detrimental to DCS signal. Lastly, I’m not sure if the switches prefer less than the max output of some transformers. Many transformers have a14V ish aux out. The is often sufficient. 

@Marty R I figured as much(and certainly hoped as much) when I was watching a YouTube video and someone said they were using the TIU variable channel to power switches(never heard of it, and thought it sounded like a waste of a channel). 

The trackpowered turn-out part is extremely helpful. In my previous layout- i had one small portion where I transitioned to tubular track so I could insert an O/31 manual switch for what was a “stub siding” used for show. I always had goosignal on that layout, however, and want to keep it that way!

finally, per the manual, “The RealTrax switch operates in only 10 volts and 1.25 amps”. 

Will keep you updated for when it’s up and working!

Forgive me if I seemed rambling or a bit incoherent. I injured my head and got a concussion earlier in the week(2nd in a year, 7th overall) so I am having some difficulty communicating talking grammar and especially typing.

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