The push-button light brick seems to be popular with Lego at the moment, and included in quite a few sets.
I'd like to find a way of being able to operate it remotely, so that I can include the lights within a Cityscape and switch them all on and off easily.
The button obviously can be connected to a technic axle, but is there a simple way of motorising an on/off push?
(I know I could alternatively use the PF lights, but they don't always seem to be as easy to use in place)
Yes, the easiest way would be to get the following: a powerfunctions remote control, battery box, moter, ir reciever, and z-motor. The total cost is $36 and you can get all this on LEGO.com except for the z-motor, that part you have to get in a LEGO set as the following: 8052. 8053, 8110, and the LEGO Technic yellow actuator which I can't find the set number of right now. get a 1x4 axle (usually black) put it at the far end of the z-motor and into the light brick. Get another 1x4 axle and put in the other end of the z-motor and into the regular motor, hook the regular motor into the receiver, and the receiver into the battery box. Make sure the remote control and the receiver are in channel 1. Make sure the green light is on, on the battery box. The battery box could stay on for about a week without needing new batteries. flick both of the levers on the remote and the light should turn on. You could also get the rechargeable battery box where it plugs into an outlet and never needs batteries. You could run 32 lights on 1 remote.
I would tend to ignore the fact that there is a Technic cross hole in the light switch. I guess it may be handy in some cases, but frankly it seems easier to me to just push the button with a lever or cam.
To do that, the best part is probably the Technic Cam, possibly two of them side by side. Don't drive it through the center hole but through the one just next to it, that is, the middle one of the three adjacent ones.
Positioning it so that it pushes the switch shouldn't be an issue, but of course you'll also have to motorize it somehow. I guess the easiest would be the new servo motor but you'll need to wait for it to be available separately (should happen during 2013), and of course it takes some space. (If you want to be creative with precision positioning, you could use an old 12v train switch remote too, I guess).
Of course, any motor will probably do, but then you'll have to make sure it doesn't turn too fast or it's going to be tricky to hope it stops in the desired position.
Another wacky idea would involve a wormscrew right on a rack, which would slide in or out of position, but I'm not sure it would be that easy. And if you're willing to go that route, a simple actuator is probably easier.
I see that you considered the use of PF Lights, but discounted them as they were difficult to integrate into your models. Maybe you could use the older style 'Electric, Light Brick 1 x 2 with Single Side Light'
This has the obvious advantage of being based on the standard 1 x 2 Brick for ease of integration but is also smaller than the push-button light brick (2 x 3 x 1 1/3) it would replace, and therefore hopefully be easier to fit into the available space in your models. It can be connected using 9v Wires and/or Electric Plates that are available in 1 x 2, 2 x 4 and 2 x 8 sizes. You could then use any of the 9v battery packs or power supplies to control the light.
The link you specified is to the light brick with a yellow light but they are also available in other colours. So for like-for-like replacements you could use a single 'Electric, Light Bulb Cover (Colored Globe)' to tint the light to match the light brick you replace.
