Many of my students have been using an air/ acetylene torch and now want to have a torch that has the extra heat that oxygen brings, like the Smith "little Torch".
A lot jewelers use the "little Torch" with propane and oxygen, which is nice, and clean and moderately hot, but if you already have the Acetylene tank and regulator, you are halfway there....just add a tank of oxygen and its own regulator, and add the "little Torch" designed for acetylene.
But here is the cool thing.....you don't have to give up your original air acetylene torch that you are comfortable with and already paid for!!! Add a "Y" splitter to that acetylene tank for about $35 and hook back on your original torch. Yea!
Now why would you want 2 torches? Well, your ambient air/ acetylene torch is good for many operations, like annealing, or soldering large cuffs or belt buckles, but is limited in temperature when using a small tip. It's about the opposite of the "little Torch", which is small and hot, but not as ideal for that annealing job or any situation where you might want larger overall heat rather than the hot localized heat of the "little Torch".
The "little Torch" used with acetylene instead of propane is very hot and can be a bit sooty if you are slow to add the oxygen when lighting it. There is a bit of a learning curve, as with most new procedures, but my students use them in my classes and many have asked me for info to purchase one for their home studio.
Here is what you'll need: an Oxygen regulator something like this:
or this from Eurotool about the same price: http://eurotool.com/products/SINGLE_STAGE_OXYGEN_REGULATOR-4555-98.html
add an oxygen tank ..... usually best purchased locally from gas supplier or buy used