.------ to power switch
10uF /
+|| |/ BC547 /
----+-----||-+--[1K]----| (or 2n3904 etc)
| || | |\|
from LED [100K] -+- ~\
| /A\ 1N914 |
| | |
-----+--------+------------+------

Thank you very much Jasen, I'll look into that. I hope to have a
working prototype for this weekend (especially if I don't need the
relay).

Mauro