Wireless (sorta) train camera

[coke]

So we have this train set (mini), it runs along a track that I believe provides the engine (via the track) a constant 12vdc. Rumor has it that Axis 207W's (and probably similar models) can operate under a few AA batteries, and the transformers for them plugged in are 5.1vdc. Any thoughts on what I would need to convert the 12 to the 5.1 that the camera needs?

The thought is to plant a wireless 207 on the engine (I've weighed them by hand, the engine weighs a bit more than an actual 207w), and have it broadcast it's trip through the track. I could certainly put some sort of a battery pack, but any clues on how to just pull the 12 from the track and make it the 5.1vdc that the camera's happy with?

(In case anyone's wondering, I've already done the math that 3 AA batteries equals 4.5, not 5.1, so either these people are imagininig things, or there's some fudge room.)

TIA.

[jameswilson]

easist way is to get your yourself an heatsink and a voltage regulator, something like
http://www.maplin.co.uk/Module.aspx?Mod ... 4&doy=12m7

plus suitable heatsink