That's it in a nutshell. A DCC command station, power supply and control interface replaces your DC supply. There is a good range of choices from 'all in one box' format like a transformer controller, to separate boxes with tethered walkaround, or completely remote, handsets. Every loco has a DCC decoder fitted, requires four soldered connections if operating the motor is the only requirement. (Don't use the 'address 0' feature on some DCC systems to run a loco without a decoder, motors burn out very fast.) There's a good source of introductory information in the 'Resources' section of this site, accessible from the tab top left on the header bar.
Others may not agree, but I think that the Bachmann EZ digital controller is an inexpensive way to start - only about £35 new from Hattons (or was earlier in the year). Even cheaper second hand from Ebay. It is basic, but it does what I want it to do - just control a few engines on a simple layout.
Robert is right if you just want to try DCC out before committing yourself further.
I started rather tentatively wih a Lenz Compact bought second-hand (and subsequently sold on again!) but soon got the DCC bug and upgraded, firstly to an NCE Power Cab then further to NCE Power Pro (a simple upgrade reusing the existing equipment with no redundancies). Be aware that the Bachmann EZ system is limited to 9 locomotive addresses and only numbers from 1 - 9, plus the aforementioned address 0 for one DC (unchipped) train. The Lenz was slightly more versatile in this regard as it could address 1 - 99 (two-digit codes only) plus 0 for a DC loco, but it only addressed up to four functions - I'm not sure how many functions the Bachmann system can control. I think Roco also do a starter system but I don't know anything about theirs.
As Robert has said, there are many systems to choose from and all have their merits and their less good points (not necessarily bad, as such). If at all possible, try out some systems before committing to buy - you may be lucky enough to have friends near by with DCC systems, or a club or shop that would allow you to see, feel and test some different controllers.
Whatever you end up doing, many of us have succumbed to the lure of DCC and the flexibility of control it gives. A few of us have succumbed even further and fallen for the charms - and expense! - of having sound under DCC control.
Enjoy the experiences and don't be afraid to ask questions as there is a wealth of experitise on tap in these forums; translated, that means we've already made the mistakes and learned something from them!!!!
EDIT: Just as an aside, this might have been better placed in the DCC forum for more qualified responses from the experts ... moderators???
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