Fuse blowing up

Hello,

I had a problem, look at the schematic, I built power supply like this, and the problem was the fuse blew up always when I turned switch on. I sorted out this one with placing fuse before switch, but still I don't know what was the reason of fuse blowing up, maybe you know??

MuLdEr said:

Hello,

I had a problem, look at the schematic, I built power supply like this, and the problem was the fuse blew up always when I turned switch on. I sorted out this one with placing fuse before switch, but still I don't know why was the reason of fuse blowing up, maybe you know??

Click to expand...

You should make sure you use an anti-surge fuse, particularly if using a toroidal transformer - toroids have a much greater switch-on surge than conventional transformers. As the toroids get larger, you need to implement soft-start circuits.

Placing it before, or after, the switch shouldn't make any difference, electrically it's identical.

Inrush current at switch on, definitely. Especially with all that capacitance after the rectifier.

You must use a slow-blow or an anti-surge fuse.

JimB