In article ,
PJO wrote:
The ones I've got had a choice of lenses and also allowed some
adjustment in the horizontal plane. So they're mounted in the
'conventional' place. They seemed to cope ok with a cat when I last
had one, but she was fairly old and didn't jump that high. ;-)

Yes. I'm familiar with those types of PIR. Problem is that if they're
mounted in the conventional place and a pet alley lens or PCB position
is selected the overall sensitivity is quite poor in relation to a
standard setting/lens. You can't have it all ways. Pet proof always
means less coverage/sensitivity. The other common method is to use
multiple pulse count. Most PIR's have the capability to pulse count to 4
but to be honest the average person moving at normal speed will only
cause the average PIR to actually trip once or maybe twice at a push so
it would be possible to walk through the room without activating the
alarm.

Well, I did a walk test, and it proved impossible to cross any room from
door to window without triggering it.

So, it's either per alley dual-tec, perimeter protection or poor
protection!

I tend to think of the PIRs as last ditch protection as I've got switches
on all the external doors and windows, and a few pressure pads too.

--
*Women like silent men; they think they're listening.

Dave Plowman London SW 12
RIP Acorn