Compatible HO transformer with RealTrax switches

The only model "1440" I found on the MRC site was this RailPower 1440 combo transformer and sound unit.

If this is what you have, it's under-powered.  Total output power is 13 VA which is equivalent to 13 Watts for the matter at hand (switches and accessories for a 34 x 8 layout).

Do you have any suggestions on a transformer to run the switches and accessories.  This is going to be a very large setup.  It will have a total of 3 tables 4 x 8.

Can I use that transformer to power my switches and accessories on a 4 x 8?

Ask 10 guys for a recommendation and you'll likely get 10 answers... actually more than 10 since it really depends on what kinds of accessories you have.  

And the answers will be all over the map.  One might suggest using one or more channels of your ZW controller.  That is, some accessories operate "better" at certain voltages even if the instructions say it works over a wide range.  So, for example, you could use 2 ZW variable channels to provide a low-voltage bus and a high-voltage bus just for accessories.

Another line of inquiry would be if you're talking a lot of lighted buildings.  Most new buildings now use LEDs instead of bulbs.  These can be driven using DC voltage for which you're better off using a DC output transformer which are generally much cheaper and more compact that AC output transformers.

As for your 1440, it apparently puts out 18V AC.  18V is on the high-end of the Accessory voltage range.  I'd say the sweet-spot for AC accessories is closer to 14V.  As for its 13 Watts of power.  Consider that a Realtrax switch has 2 bulbs (on the turnout and on the controller lever).  Each of these bulbs draws about 1 Watt (at 14V).  Drive it at 18V and you're pushing near 2 Watts of power into each bulb.  They will be nice and bright but be ready to change bulbs.  And you haven't even fired the turnout which is where the real power is drawn!  Actually it might be instructive to simply take your 1440 and power up a couple Realtrax turnouts on the bench.  I'm thinking with the bulbs glowing brightly you might not have enough power to flip a turnout.  Your mileage may vary.

Hopefully others will step up with different perspectives...

The topic of your question is not really as related to the plywood tabletop size as it is the number (and type) of things you plan to power with it.  The size is not as relevant.  (a quantity of 3 4x8 boards is not huge in the world of O Gauge.  It's nothing to sneeze at, but quite a few of us probably read your original post as a 34 x 8 layout, which would be quite a larger beast! )

Switches are a temporary load (aside from the indicator lights, which are of course always on), and you generally wouldn't likely need to switch more than 2 simultaneously (like if you had a cross-over from one loop to another).  Maybe it would work OK for just powering 2 (or a few more) switches.  18 Volts AC is probably OK, but most switches can get sufficient actuation using a lower voltage.

Accessories will be  much bigger question, as some may not like being operated at 18 volts, even if you do have enough power available.  Also need to know if you want the accessories to be able to operate simultaneously, or is one at a time OK?  If the later, you can get by with one transformer for accessories and adjust the voltage to whatever works optimally for each one.  (might want a dual output one so you can leave the one output for the switches and the other for adjusting for accessory use)

But as Stan said, the power pack you have from your HO days has a pretty low total capacity.  And if that is the one, the info Stan put the box around doesn't give any information on how the power is split between the AC and DC outputs.  With the (comparitively) lower demands on the AC posts for HO, there may not be much available at the AC output.

I suggest deciding what you want to power and providing that detail, it will then be easier to suggest a good candidate transformer for your needs.

Also, you have a ZW, which has 4 outputs, are you really going to use all 4 for different blocks or loops of track?  I realize it's certainly possible to put 4 independent tracks on the table you have defined, so maybe you have that part properly figured already.

{edit: I swear, I really started typing my response before Stan posted his. .  It seems we came up with some similar concerns/questions though.}

-Dave