PIR Timer Lighting Circuit

Thread Starter


Joined Jan 18, 2012
I have been assigned a project to design a lighting circuit for a work bulding, so that when egineers enter the site the PIR activates the lights and a timer, after 30 minutes the lights either need to dim (although i understand its hard to dim modern luminares) or switch half the lights off in the room. This indicates to the engineer that they need to reactivate the sensor and resets the timer. if no one reactivates the sensor then the lights will completely switch off within 15minutes, so 45minute cycle from activation to the lights switching off.

I am struggling to actually design the circuit, if anyone could help me to complete a design and an component list. If you could identify what timer chip(s) could be used i would be most appreciative.

Thank you


Joined Jul 18, 2011
It seems there's a lot of timer applications today.

I'll tell you what I've told other folks:
Depending on your skill and experience, an MPU is the best way to go. Something like an Arduino or Basic Stamp should work - and be very flexible.

The logic is pretty straightforward. What "luminares" are you driving? CFLs, LEDs, or incandescent bulbs?

Thread Starter


Joined Jan 18, 2012
I think they're CFL luminaires. My experience with circuitry is minimal and I am especially inexperienced with MPU's.


Joined Aug 7, 2008
Assuming that you have two groups of lights, each controllrd by electromechanical or solid state relays, A & B requiring 5V control signals, then maybe the thumbnail ckt would work. PIR module triggers a 30 min timer [ 555 IC ], leading edge of output resets second timer, 15 min. If there is no movement to retriggeg 30 min timer, falling edge of timer triggers 15 min timer. Both timers are combined in OR gate to drive relay driver-A, RDA. RDB is driven by 30 min timer. With movement, light bank A & B comes on; with no movement, bank B goes off, while bank A remains on for another 15 min. Movement restarts the whole cycle.


Thread Starter


Joined Jan 18, 2012
I need help designing a light timer circuit, for a building that I work in. The system idea is that a PIR is activated by entrance into the room which activates a timer circuit to control the lights. the lights will stay on for a total runtime of 45minutes, but after 30 minutes half the lights will switch off to give a dim effect. This will alert any one in the room to reactivate the PIR and reset the circuit.

I am looking to use the timer below;


Using 2 timers, 1 set at 30 minutes and 1 set at 15 minutes. when the 30 minute timer finishes it wil activate the 15 minute timer.

this is my theory but i am not 100% certain it will work as i want. Can anyone confirm if it will or suggest a way to set it up.


Joined Apr 5, 2008

I have moved your post from the completed projects forum to your old thread, as I contains extra information and made it visible.
In the completed projects forum it will stay invisible.



Joined Nov 30, 2010
Those modules look right for this job. Your part wil be to have the PIR close the contacts of both START switches instead of applying voltage. A DPST relay comes to mind. Wire its coil to the PIR output and wire its contacts in parallel with the START buttons so it can close the two START circuits. Set one timer to 30 minutes and the other to 45 minutes instead of having one timer communicate with the other timer. Repeated PIR events will reset both timers and the delay criteria will be met.


Joined Dec 28, 2011