You could pot it in resin (e.g. car body filler), or wrap it in self-amalgamating tape.With the coil outside the alloy box, I still need to protect it from the wheater elements any tips fot that?
No. You get a ~20mS pulse in the coil as soon as the reed makes first contact (contact bounces in the interval up to ~10mS from first contact shouldn't affect the 2:1 divider).About the circuit, does it matter how long the income pulse take?
Coil energisation is for 20mS, even if the reed stays closed (parked).