OK, that would be great if I knew how to hook up any 3 terminal regulator. The last time I fooled with electronics was in the Air Force in 1962. A lot has changed since then!
The best thing to do is to get a datasheet for the device (just google). It will show you all you need to do (and vastly more). In essence the input pin connects to the input +ve, the output pin connects to your load, and the adj pin is connected to the common ground for your input voltage and load. (this is for a non-adjustable 1.25V regulator)
See Gorgon's point above and my response below however. If your lamp is always attached, you will have no problems. If you have something to switch it on and off then a 240 ohm resistor between the output pin and the adj pin (ground) will ensure that your output voltage remains stable.
Yes, it certainly does, THANKS, but what about the current? What kind of current is it putting out at l.48V?
The 317 is a voltage regulator. It will not limit current unless it gets to a limit which causes it to go into shutdown. This means something over an amp, or when it gets very hot.
Depending on your load (what is it -- a lamp?) this won't matter. The lam p will only draw a very small current. The 317 can (not will) provide more than that, so it's OK.
Another important factor is the dropout voltage. At low currents it may be about 1.2V. This means your input voltage has to be higher than your required output voltage by this amount or more. Typically we'd say it's 2 volts. So you need 3.25V input to get a goos 1.25 output.
Don't you need the 240 ohm for the reference to work properly,
That's true of any three terminal regulator really, but moreso for the adjustable ones because they aim to have a current through the adj pin that is close to zero (where the fixed regs do not.
Input and output capacitors are likewise a good thing.
