In article ,
robgraham writes:
My garage is separate from the house by about 20m. There is currently
a bit of a worry about security and I have rigged up a burglar alarm.

It then struck me that it would be a bonus if I could link a smoke
alarm into that too. Electronics is my training so I don't have any
problems in that area, but I've dismantled the smoke alarm (ie got it
out of the plastic !) and am puzzled to see that the piezo sounder has
3 leads - why ?.

The IC is under the sensor cover - would anyone know if that is likely
to have a dc output rather than the switching one for the sounder ?

Look at this thread:
http://groups.google.com/group/uk.d-...205e3d276d90f2

--
Andrew Gabriel
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