Timelapse Power Protection


My project is a timelapse utilizing a DSLR, arduino, steppers, and some USB devices. Their various power consumptions follow:

USB (arduino, GPS, etc) = 5V 2A DSLR = 7.4-9 V 2.5A steppers = 12 V

I will use a single 12V source ([3S3P 3.7V LiIon batteries, or 12V DC wall wart) to power all of this. 2 voltage regulators will step down the 12V, 1 to 5V for the USB hub, and 1 for the DSLR.

My concern: This equipment is expensive to me. What suggestions do you have to protect this stuff form a voltage regulator (or wall wart) blowing and destroying the camera, etc? The obvious solution is a fuse.

As far as I can google, a fuse will give over–current protection... but is this what I want? Would this not protect me from over-voltage, the thing I should be most concerned about? If so, what kind of fuse ratings would I choose? E.g., would I want the fuse to burn up quickly or slowly? What voltage/current/other ratings would be appropriate?

Thank you for the help.

fuses mostly protect your power source not whatever is drawing the current... if you have something seriously screwed up to toss a fuse it may have been too late

as far as overvoltage some simple 78 series 3 pin regulators will take care of that (7809=9v, 7805=5v etc) they limit themselves at a total MAX of 1 amp if everything is sparkling white perfect. similar higher current models are available but 2.5a is something that some more serious desgin may be needed

(why is an arduino sucking 2 amps?)

The project is still in assembly, so I do not have a definitive power draw yet. The USB hub will eventually service multiple devices, not just the arduino (i.e., external flash drive), with a max of 2A.

Thank you for the help—exactly what I needed!