> Possibly a 4001. Two gates as a re-triggerable monostable

Just thinking - you don't need a flip-flop to store state. If pulses
are lost, the output from a monostable (4001, 555,  whatever)
would go low and the relay will drop out. By that reasoning do
you need a WD chip anyway ? If you've got a periodic output
from the PIC, that could go to an RC that holds up the g/b of
a FET/transistor, keeping the relay on. Without a PIC I/O pin,
perhaps integrate OSC ?

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