can anyone help?

i have a pir that points at the front door and goes off when letters come through.

is this normal? and why does it happen?

hac

NO! I think you have radioactive letters. Try moving the sensor to diffrent location.

Its obviously sensing infra red somehow.

Either move the sensor or mask out the part of the lens that is picking up the letterbox.

It would probably be easier to move it.

Edited March 17, 200422 yr by simonrob

Could be cold air comming through the letterbox.

Is there a metalic internal letterbox flap; if so, this might be reflecting another IR source as a letter swings it up.

Check the pulse count in the PIR, 1 is a no no!

thanks for your help

i do have a metal flap, which is coming off!

i`ve angled the pir away, how do you adjust the pulse count, it`s a reflex pir

There are usually two set of pins on the PCB, one for LED on/off and the other is the pulse count (may be numbered 1,3,5) - move the jumper to another pair of pins - the higher the number the lower the sensitivity.

But as its a reflex personally I'd change it for a real PIR.

Remove the top right hand side jumper to enable the SLOW pulse.

resite the pir to above the door loking into the hall = problem solved