23rd
NOV

DC 12V 24V PIR Motion Sensor

There is a small problem with this motion detector and that is that the detector is not sensitive to light.
Usually modules are light sensitive and they can distinguish between day and night.

Fortunately, pin 9 of BISS0001 is reserved for this case.
It is designed so that when the input voltage Vc on pin 9 is high, the PIR input is enabled and when Vc is low, the PIR input is disabled (Vc <0.2 Vdd = disabled).

 

This can be achieved by using an LDR (photoresist) “Trigger Disable Input” between pin 9 and ground.


This will be quite enough for darkness or twilight detection but for setting the light intensity you have to replace 100k Ohm with a 1M Ohm potentiometer.


LDR‎ – Light Dependent Resistor

1000 lux bright sun  ~ 150R
100    lux daylight      ~ 2k ohms
10      lux twilight       ~ 10..20k 100..200k
1        lux dark             ~ 100k
0       lux                       ~ 1.0M..10M

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