Uses & Operation of a Fuse

Video Transcript

" Hello! This is Ross on behalf of the expertvillage.com. Fuses provide protection to a circuit. Now, if something fails in a circuit and it tries to draw more current than it should, then the fuse burns out. So, fuses are rated in how much current can go through them. This one is a small one and it says on the side here, it is good for 250 milliamps that is a quarter of an amp. Once it flows through the current greater than that then what happens the film in it will burn out and you will have a open circuit. These have pigtails on it. The idea was you could solder into a circuit that you are building. So, you stick on the component side solder it up. It becomes a problem if you burn it out because if you burn it out you have to re-solder and stick a new one in. So you could use it where it would clips instead, you can set it into the board through clips and just pull it out popping a new one in. You do want to fuse though because it will protect it. If something happens in the circuit, if you short something out like even just touching it, it burns out instead of drawing too much current through a component that couldn’t handle it. There are other devices that work like fuses to protect it, you can put in the automatically reset themselves. Now have this fuse wired up to my power supply, I have it turned down now. When you are designing the circuit, its operation will vary in terms of the amount of current that it draws. You want to be careful about fuse you pick. You want to pick a big enough one, so you make allowances for the changes in the current flow. For instance look at your computer, when your computer is sitting idle and the hard drive is not turning, the fans are not turning or if it is running really quiet, and then you ask it to do something you hear it wind up sometimes, it is demanding more current at that point, more power to make it work. So, here is a fuse. I am going to go ahead, if you watch, this is like a light bulb. The fuse will get hotter and hotter until it burns off and you will actually see a glow and it will melt the filament that is in there. So I am going to start turning up the available current to it and it will just flash like… almost like a boom! there it goes. It melted that. It exceeded the threshold of the rating for this fuse and then protected the rest of the circuit. So, now you would have to replace it, unless its an auto resettable one or like a brake you can just push a button to set in. "