My son found one of these and he was curious what it was.
I showed him how to test it with a multimeter to show if it was blown and then proceeded to take it apart to show him the insides.
I expected to just find something similar to a glass fuse, but instead found lots of interesting things...
- Sand of some sort
- Fiberglass wrap (at least that's what my now prickly fingers say it was!)
- A thin flat copper wire with a hole or two in it
- A block of copper on a spring that appeared to be once soldered to a copper base
I have some ideas of what purpose each of these does, but I was hoping to get a larger idea of the design of these. Is the flat copper wire also meant as redundancy for blowing the circuit? Is the soldered piece the primary? Why the hole? How do they calibrate the solder release with the amperage? What makes this fuse a time delay?