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I’m new to the DCS world and am trying to incorporate it into my layout because I like some of the exclusive engines they have.

Can I supply power to the track bypassing the TIU to avoid frying it by over current? But use the signal from the TIU by using AUX power to power the TIU? And if this is possible do I just have to run feeder wires from the black (ground) terminals on the TIU?

Last edited by Rich Melvin
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Yes.  It's called "passive mode" and was discussed in this thread:

The TIU channels can handle 10 amps apparently.  Are you expecting to exceed that?

Two other things to consider: if running conventional locos as well, your Protosound 2/3 ones will be limited by the voltage you supply to the track.  Might not be an issue with Pullmors, but it will definitely be an issue with something like an MPC with just a single hobby motor.  Those will race around the layout at voltages too low to even fire up a PS2 or PS3 engine.   The TIU has variable channels which allow you to send the track a variable voltage with the power supply at a constant 18V.  If you're running TMCC/Legacy, there's a cord that allows you to connect the command base to the TIU and run both MTH and Lionel command-equipped items with the DCS handheld.  You can still use the TMCC/Legacy remote for those items only.

It's actually easier to protect the TIU using Passive mode. You can place Transient Voltage Suppressors on the track side of the TIU which prevents the spikes from backtracking into the TIU. It also allows for bigger power supplies. The only down side is that the E-stop function doesn't work on the TIU (we have panel-mounted buttons on the layout that shut down the whole layout).

Our new layout at the club is using DCS in passive mode for the exact same reason, while the TIU is designed to handle the current, logic says if it doesn’t have to it’ll work longer. It was found a few year back that a 22uh choke helps keep the power clean and ready to accept the DCS signal. Check THIS thread.

for this I came up with this PCB to hold the choke plus a TVS diode.

for information on the TVS diode put simply just search TVS diode of the forum and you’ll get more information that you’ll ever want to know.

I actually have a new run of these PCB’s for passive mode operations if interested contact me via my profile email address



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