Diy mini A/C power protection circuit (help needed)

Thread Starter


Joined Dec 19, 2017
Hey guys need some help im trying to take 12v and step it down to 5 with only 450 mah from a barrel jack dc power input while adding a over/under current protection circuit as well as thermal protection i.e. automatic shutdown but im literally just getting started wold anybody mind just drawing out a "diagram for idiots" kinda thing or just to point me in the direction of one? thanks but help of any kind at all would be helpfu;
Also a beginner here, so I don't think I can help to a great extent :D

What kind of circuitry/components are you using to step down the voltage?

By the way, linear voltage regulators are very very easy to use. Perhaps you can check those. It's just that they aren't really efficient, especially for quite a big input-output voltage difference (in your case, 7 volts). Wasted power is converted into heat, it's the product of voltage difference between the input-output and the current being drawn. For your particular example, P = (12-5)*0.45 = 3.15 Watts. That's a lot, and you definitely need a heatsink.

Many newer linear regulators have safety features baked-in. The L7805 is equipped with thermal overload and short circuit protection built-in, so you have less to worry about protection circuitry and stuffs.

There are other alternatives such as switch mode regulators (a.k.a buck converters). These are more efficient yet a bit harder to build. But you can always get one as a pre-soldered module, and I'm pretty sure a lot of them have built-in protections as well.