I want to create an adjustable power supply for my electronics projects, and the cheapest/fastest option seems to be using an LM317. However, I do not want to blow things up by doing something wrong (what is pretty possible, considering my little knowledge in electronics), so I want to have a few questions cleared:
What power should R1 be able to handle, considering a maximum drop of around 30v (from 32v to 1.25v) and, let's suppose, 1A of current (I have no idea of how much current I'll use, but I'm setting the value high to make sure)? If the calculation I did are correct, the power dissipated by the LM317 is of around 30w (I have a huge heatsink, heat on the LM317 shouldn't be a problem), but what should be the rated power of the resistor? 30w resistors aren't cheap, and the store I buy components from only offers resistors up to 10w (that are also very expensive).
Do I need a capacitor between the input of the LM317 and ground? If I don't use one, what could happen?
If I wanted to put a LED to indicate if my power supply is on, how could I transform my input voltage of 32v in the voltage of the LED without having to dissipate a ton of heat, and without expending much?
How can I protect my circuit from a short circuit, so I don't blow everything if mistakenly connect something wrong?