GRJ,
Finally got to trying out one of the WD timers PBW's you made and it works fine here. I tried it on one spur track and it worked. While under the layout (scratching my head, looking at all the wires I have added and not documented 
) I thought why not just connect it to the MTH terminal block I have feeding loop 2 with all the spurs and sidings on it. I have only been fiddling with one train and a PS3 RK RS3 engine, but that seems to work fine too. It's one of the newer ones that also starts with the thumb wheel, tried starting it both ways. I will get the rest of the trains back on the tracks and see if all is still well, but I see no reason they should not be just fine.
Forgot to add this earlier: The DCS-RC's green LED came on green when powered up and had a blip in it at just about 1 sec as near as I could time it with my watch. Pretty close anyway.
FWIW, if it helps with problem solving, here is my setup right now. Loop 2 (the one tested) is a center rail isolated loop using Atlas O-54 track. It has 2 inner sidings and 4 inner spurs. There are 4 blocks on the main and each siding/spur is isolated coming off the switch that feed it. The sidings and spurs are switched with LED rocker switches at a small panel. Each switch powers a relay that actually switches the track power, center rail only (small glitch with the switch's LED commons). All the power comes from an MTH terminal block and that is where I now have the DCS-RC PBW connected in passive mode. It feeds the entire loop, all sidings and spurs. Power source is PH-180 to PSX-AC to TIU to MTH terminal block, Legacy connected to TIU commons.
I will try the rest of the timers PBW's tomorrow with the same setup above. Will let you know on that too.
These are really pretty cool little devices, work great so far and no more watchdog problems. Just flip the power switch and go when ever you are ready! Also finally got my gantry crane track, found it on the front porch a couple days ago.
(Oops, was re-reading the problems above and noticed the proper name - Perpetual Barking Watchdog (PBW), post edited). 
