Yes, John, that is HO and I think it's great!
This next bit is about Arnold, therefore is N-Gauge, but the principles seem good and useful for any scale.
Although many will know this material inside out, there will be others who have never seen it before, so I continue to add to this informative thread.
Here is a scanned diagram of Arnold's End-Off solenoid wiring, which is built in to their turnouts.
The principle is that the remote electrical control switches no longer need to be momentary contact, as the power is automatically cutoff by the electrical switch in the turnout itself. This enables the still powered remote electric switch to fulfill other electrical functions as shown in the diagram following this one.
This diagram shows how the Arnold remote switch is directionally illuminated.
(Don't be concerned by the squiggly little 'thingy' just to the left of the solenoid case - it is only the mechanical linkage from the solenoid to the turnout.)
This diagram expands the previous one in showing how colour light signals can be included with the remote switch directional indicator.
I must confess that although I fully understand 'end-off' electrical switching, I am still confused as to how, at the same time, "current can continue to flow", illuminating the remote switches and colour light signals, without flipping the turnout back the way it was before the button was pressed!
While requiring a little more thought and work, Doug's suggestion that route indication may be better served by separate power circuitry, I find that a good deal easier to understand than Arnold's method. Having said that, there is no doubt that Arnold's system worked, so I guess I'd better concentrate my mind a little more!
I would just add that I always thought Arnold's track looked horrible, the turnouts looked even more horrible and the external, surface mounted solenoids added one more touch of horribleness! So I never bought any.
But the electrical principles appeared to be ingenious.
