DC power supply to get for On30

A good DC power pack that's used for HO will work fine.  I've used Bachmann's Spectrum Magnum power pack, which worked really well.

You can also try the Railpower DC packs by MRC (either AA300 or AA370).  Those are nice packs, durable and work well.

Also, the used market yields some nice DC power that will be perfect for On30.

Eddie, I bit the bullet and ordered a variable DC supply 0-30V, 10 Amps on Amazon for about $80 which I can use for a heck of a lot of other things besides running trains (e.g., robotics/animatronics or Arduino).  I'll add an inline fuse to make it a bit safer.  2-3 amps if running two On30 or HO sound about right?

Does your logging engine run in one direction only? 

It sounds like you ordered a general purpose "bench top" type DC supply?  Most, if not all, DC power supplies for train applications have an integral switch to flip DC polarity and hence direction.  So you might need to add a so-called DPDT switch to perform this polarity/direction reversal.  

I have a bunch of DPDTs.  I'm actually thinking about doing a switchback set up to climb up about a foot of elevation (back and forth 3 times) so I'd have to figure out how to automate that with sensors and relays or microcontrollers.

An automated switchback operation sounds like a fascinating project!  As for the power supply, obviously the length each back-and-forth segment determines the grade in your 1 foot climb but I suspect you'll need a method to select from an uphill (higher) and downhill voltage.  Do you already have the turnouts?  Those presumably need to flip automatically too.

I'm thinking 2 Amps DC should be sufficient.  After all, you shouldn't be pulling logs UPHILL right?   

I'd be curious your thinking on when to take the plunge and go with a microcontroller (Arduino, whatever).  I figure whether microcontroller or not, you still need:

- at least 4 sensors (bottom, switchback 1, switchback 2, top)

- a DPDT relay to reverse voltage polarity

- a 2nd relay or similar power-switching electronics to select from the uphill and downhill voltage drive

- 2 electronically controllable turnouts for switchback 1 and 2

Yes, I realize an Arduino that can run this operation is just a few bucks.  But if you choose to go "old-school" I think you can also do this Lego-style coupling various low-cost eBay modules.

Do not have the turnouts but am unfamiliar with HO/2 rail gauge switches.  I'll attach the plan (this is a draft and will adjust in the field).  There is a bottom, a top and two stops in between.  Seems to me that you simply need to flip polarity at each stop and route that polarity appropriately to each switch, but I'm unfamiliar with what kind of wiring the various switch controller expects.  Would love an explanation if anyone knows.  I plead ignorance as I'm new to O gauge and HO was 40+ years ago.

Perhaps someone familiar with On30 turnouts can clarify non-derailing products. 

In this Atlas HO turnout, the points are "weakly" spring-loaded and can be overcome by the weight of the train wheels for a train entering the turnout from the wrong setting (i.e., entering from the "diverge" branch when turnout set to "straight", or vice versa).  It appears in your draft that the turnouts are "straight" to ascend and "diverge" to descend.  Then, to your point, matters are simplified with switchback sensors reversing DC voltage polarity.

I was thinking a ~50 cent reed switch could be used for sensors.  A 10 cent Neodymium (Nd) magnet disc could be placed on the engine.  In this Atlas HO turnout, it's a simple 3-wire hookup.  One wire is common.  2nd wire sets the turnout one way, 3rd wire sets the other way.  So if On30 turnouts work like this, you would simply flip both turnouts when the top or bottom sensor is tripped.

I'd also think some kind of delay timer would be nice to have at the top and bottom...giving time to load/unload the logs.  Easy to do in a microcontroller but also many delay-timer relay modules on eBay for $2-3 dollars.  

Finally, I assume this engine is running fairly slowly so instantly reversing voltage won't whiplash the load cars.  Otherwise some form of voltage ramping or stepping at each reversal point could add visual appeal.

I like the weakly spring-loaded concept.  I wonder if light cars would be "sprung up and out" so to speak and derail.  If anyone in the On30 world knows which brands might work best in this application please chime in.  A timed stop is my thought too.   I suppose that I could use diodes to minimally reduce track voltage in a few subsequent sections as the consist gets close to the stops.

Two mountains at the corner (yellow) with 3 long spans between.  May just use a forested mountain backdrop on Masonite and call it a day.

I dont know how many amps I would need to run 2rail O guage layout.  How much would a person need for that?  thanks

WB47  I really don't know.  I'd check over with the folks in the 2-rail forum for the most definitive answer.