Any way to toggle Fixed Channels on and off?

Have you considered using a channel on the AIU to switch the track power?  That would allow operation from the remote.

That most likely work, I would think I would need the AIU to activate a relay that will turn the power on and off for the track power.

Not sure what current the AIU handles, the Lionel SC-2 or ASC handles 15A for each channel, plenty for the track.

I looked in the AIU User's Manual, but I don't see it.  Perhaps in Barry's book?

I found this page that states that the AIU uses 10A relays, sounds like that should be sufficient.  Wiring power Through the MTH AIU to Track or Accessories

Thanks I will give it a try.

Jon,

I found this page that states that the AIU uses 10A relays, sounds like that should be sufficient.  Wiring power Through the MTH AIU to Track or Accessories

Unfortunately, the article is incorrect. The AIU relays handle 4 amps each. Look at page 87 in The DCS O Gauge Companion 2nd Edition.

This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!

Bummer, I looked through the book but didn't find that.  Don't know how I missed it.

I think the aux relay is the way to go given this fact!

I agree

Ok so what type of relay do I need?

I have never set anything like this up before.

Would this work?

24volt AC 10amp relay

Looks fine with one reservation.  It requires at least 19.2 VAC to reliably pick up the relay.  As long as you have more voltage than that for the control voltage to the coil, it looks great.

I'd probably go for some of these and add a diode and cap to an 18VAC transformer output for the coil circuit.  Price is right at $1.42, and shipping is very reasonable from Digikey.

15A 12VDC Relay

John

Why add a diod and cap to the transformer output?  

Jim

Because this happens to be a DC relay.  I was looking for something that would trigger on typical transformer voltages, the 24 VAC relay was on the edge.  If you have a high enough voltage, you could go with the one you pointed out.  Also, the one I found was dirt cheap.

You could just use an HO DC transformer to power the control circuit, no extra components needed.  Since the AIU switch and the relay coil will be a separate circuit, you are free to use whatever voltage you like for that control.

Thanks John

Will order now and try it out.

When I turn the track back on using the relay or even just a normal switch will the locomotives start up in Command?  

No, they will come up in conventional mode - neutral with whatever smoke and sound level the conventional pots/switches are set to.  To force them into command mode select an engine and press either Start Up or Shut Down.

Jim,

I also wanted to be able to turn sidings, spurs, and sections of main track on/off. There are a variety of reasons for doing this, but that is not the subject here.

Although using the AIU would work fine, I am instead of using toggle switches at the control panel to control the relays. I am not using the toggle switches themselves to turn the track power on/off because it would add way too much wire. On my previous layout, which was much smaller, I indeed just used toggle switches for this.

Altogether I will have eight modules of six relays each when I am done. Right now I have half of them wired, and the tracks that don’t yet have their relays simply remain on all the time.

The only drawback is what you brought up and Gary answered; i.e., when you switch the track power on to the full 18v, the engine comes up in conventional mode. It is not a big deal to address that engine with the remote and get in under DCS control. However, if you have several engines on that track, then it becomes a bit tedious to do each one.

I have my two Z4K’s wired to the two TIU’s such that I can lower the handle of the Z4K output that feeds the TIU channel(s) for the track(s) that are off. I can then turn that track (or tracks) on, raise the handle, and everything is under control.

Good luck,

Alex

Why not just shut down the locos and leave the track powered, unless you want to keep the recorded hours down?

Whether you use relays or toggle switches at the control panel (latter is simpler), the startup issues are the same.  An alternative is to hit the TVC button on the remote, and then scroll up the voltage

I run a line from the transformer through a toggle to the INPUT of fixed 2 and the output of fixed 2 to my yards.  Doing it this way sends the dcs initiation code (or whatever its called) so the proto2 trains come up silent.

So, if you power up one channel after you're running on other channels, it'll send out the initialization at that point?  That's a nice feature.

Yes.  Not sure how fixed 1 reacts to this though.  If I remember correctly, you have to have power on fixed 1 input (for the tiu to function, or maybe just for it to start).  This may also be affected/cured if you power the tiu with the wall wart.  TIU experts know this answer I'm sure.

Jeff,

If I remember correctly, you have to have power on fixed 1 input (for the tiu to function, or maybe just for it to start).

The TIU can obtain power for its own operation from either the Aux. Power port or Fixed Channel #1 input. Any time that neither of these are powered, the TIU is off and will not permit DCS control. 

The watchdog signal, which is DCS's way of telling a PS2 or PS3 engine that DCS is present and to come up in DCS mode when powered up, is issued from each channel independently when that channel's output goes from zero volts to any other value.

In later releases of DCS (4.0 and greater), the watchdog signal is sent for about 5 seconds. In earlier releases of DCS, it was sent for only 1/2 second.

If a PS2 or PS3 engine is powered on after the watchdog signal on that channel has come and gone, the engine will power up in conventional mode, requiring a Startup or Shut Down command to put it into DCS mode.

This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!

Sounds like powering the TIU with an aux power supply is not a bad idea.  I wonder how much power it requires, is that in the book too Barry?

Jon,

I wonder how much power it requires, is that in the book too Barry? 

Page 93.

Right you are!   I have a 2A brick I supply it with for updates, I could just use that all the time.