Meindert Sprang wrote:
Agreed. But it can be made even simpler: buy a cheap $2 current relay and
connect the coil in series with the lamp or even cheaper: buy a $0.10 read
contact and coil the wire to the lamp 20 times around the reed contact. The
contact closes when current flows through the wire. Drive a small lamp or
LED with it and you're done. And for the life of me, I cannot understand why
this is not a standard feature in ANY safety related application like nav
lights or even tail/break lights on cars...

Meindert


Great! The reed contact idea sounds perfect. The only problem might be
mechanical if the cable is thick but, in that case, I guess you only
need few coils. It is a matter of finding just the minimum number of
coils to reach the threshold B considering Ampere law.

I will try it.

Daniele