Homebrew PCBs

That's a good calculator, they also have a very good via calculator there.

The question is what temperature rise do you calculate for?
You mustn't go over the max. PCB temperature during normal operation
(something like 130°C).

I would size the fuse trace so it can carry the normal current with
some good safety margin (esp. trace manufacturing tolerances) and then
experiment at which current it fuses in which time. Stuff like inrush
currents must be accounted for, but are probably fine. But then, I
would not do this at all!

Another weird thing I've seen is in a Tektronix logic probe. A little
wire of springy material is fixed on one end, and then bent down for
soldering on the other end. If you overload the input the wire gets
hot and unsolders itself, springing away from the joint. The manual
stresses you must not add any solder to re-set it, a bit like those
old temperature fuses which had a "rivet" of low melting alloy.

ST


On Tue, Mar 9, 2010 at 6:07 PM, Paul Mateer <paul.aa9gg@...> wrote:
> Here's one calculator I found:
> http://www.circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/
>