The only need for DCC is if you are using DCC detection and something like the Digitrax Loconet to route the signals(and you would need a computer interface as well. All very do-able, and I would look at the JMRI web site for more information. You will need detection, logic(computer), and decoders to drive all of this stuff. Wasting a sound decoder on a 'ringing bell' seems to be a little overkill unless this is a 'techno' demonstration.
You can use IR/photocell sensing to drive the signal, and nothing has to be attached to the DCC system. LogicRail and South Bend Signal both have good 'stand-a-lone' systems with flasher/crossing gate controls, and even the ring bell sound from at least one of them.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
In purchasing a Modern Over The Road Combo Crossing Gantry Plus Gate item No. #1192 from NJ International. Im going to operate this unit with DCC. How do you hook up a motorized crossing gate with DCC? I have a Digitrax DB150. I will also implement sound with the RR crossing unit. What type of decoder and sound decoder should I use that will allow me to download RR crossing bell sounds?