Automatic Light control using PIR sensor.

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HemZ

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Hi ,

I am designing automatic light control based on motion detected by PIR sensor (HCSR 501) ,

I am using Optocoupler and triac based circuit to light up the bulb. Anode of Optocoupler has 330Ω and a led connected to it. The issue is in interfacing with PIR sensor, though i have level shifted output of PIR to 5V using transistors(since optocoupler works on 5V) , it does not glow the bulb.

Any suggestions please?
 

Hi,

I assume too low current for the optocoupler:

maybe the current is (5V - 2.1V - 1.2V ) / 330 Ohms = 5mA.
(1.2V = Optocoupler forward voltage, 2.1V = LED forward voltage. Both are just assumptions)

Klaus
 
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    HemZ

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here is the schematic.
 

The circuit is driving MOC3021 through 1.8 kohm in total, less than 2 mA LED current which can never trigger the optotriac.

- - - Updated - - -

P.S.: The series connected LED would make the circuit fail even with lower source resistance.
 
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