Home     Contact     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS     Terms of services     Privacy policy  
   
 Home     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science   

Author Topic: PIR Sensor with LED Strip  (Read 4277 times)

0 Members and 1 Guest are viewing this topic.

Jon

  • Guest
PIR Sensor with LED Strip
« on: February 09, 2012, 18:12:30 PM »
Reference: LED Fade-In Fade-Out Dimmer Comment from Jon, 9 February 2012


Hi Giorgos,

Attached is the datasheet.
« Last Edit: February 09, 2012, 20:11:28 PM by kam »

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: PIR Sensor with LED Strip
« Reply #1 on: February 09, 2012, 20:14:48 PM »
Quote
@Giorgos, I got very strange result. First, when the PIR is INACTIVE (live but not sensing motion difference), the OUTPUT reading shows 10.36V. However, when the PIR is active (i waved my hand), the OUTPUT reading shows 10.45V.

Based on the PIR datasheet (how can I send it to you?), it is active LOW but yet I don't see this behaviour in the output. The LED does shows brighter and it is INACTIVE and dimmer when the PIR is ACTIVE (contradicts with the Voltmeter reading). How can I test if the PIR is working or faulty?

On the other hand, when the pull down resistor is connected, the OUTPUT reading shows between 0V and 0.22V.

Thanks and appreciate your help !


ok, i see. The datasheet shows clearly the transistor. What resistor do you use for pull-up? Did you try to power and LED without a resistor? Did you connect an led from positive to the transistor directly? I'm afraid that the transistor is toasted. Can you locate this transistor on the board? If yes, probe the base of the transistor and see if it gets 0-5 volts.

Jon

  • Guest
Re: PIR Sensor with LED Strip
« Reply #2 on: February 10, 2012, 03:11:07 AM »
ok, i see. The datasheet shows clearly the transistor. What resistor do you use for pull-up? Did you try to power and LED without a resistor? Did you connect an led from positive to the transistor directly? I'm afraid that the transistor is toasted. Can you locate this transistor on the board? If yes, probe the base of the transistor and see if it gets 0-5 volts.

The attached datasheet is for the PIR. So are you implying the PIR is toasted? I connected power to Pin 1 of the PIR, GND to Pin 2 of the PIR, power to the pull up resistor (10K Ohm) in series with a single LED and then to the PIR's Pin 3 (OUTPUT). I have no direct control over the base. The PIR only has Pin 1 - 3. I believed the base is control via the sensor. Whenever it senses motion, the base is triggered and changes the OUTPUT Level. What do you think?
« Last Edit: February 10, 2012, 03:17:29 AM by Jon »

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: PIR Sensor with LED Strip
« Reply #3 on: February 10, 2012, 07:42:34 AM »
yes the transistor is connected on the board, i understand this. you need to locate this ouput transistor on the board and maybe measure it and is necessary replace it. But as i can tell, maybe you connect the LED wrong.  The pull up resistor is connected from positive to the output. Then you connect the LED from the output to ground.
Locate the transistor and measure the base voltage. This is a good start to tell if the PIR works but the transistor is toasted (much likely)

Jon

  • Guest
Re: PIR Sensor with LED Strip
« Reply #4 on: February 10, 2012, 17:18:48 PM »
Hi kam, the led is connected correctly to the OUTPUT pin, not to the GND.
I have the sensor replaced and it is working now.

I was thinking of connecting the output of the sensor to the 555 timer to generate the fade in/out effect but worried the current output from the 555 timer is insufficient to drive the LED strip.
What do you think? Need a power transistor to drive the LED strip?


kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: PIR Sensor with LED Strip
« Reply #5 on: February 10, 2012, 18:42:52 PM »
since the datasheet do not state the sink current capability, better use a transistor amplifier - an emitter follower will do just fine for you.

Jon

  • Guest
Re: PIR Sensor with LED Strip
« Reply #6 on: February 10, 2012, 19:04:59 PM »
since the datasheet do not state the sink current capability, better use a transistor amplifier - an emitter follower will do just fine for you.

Which transistor amplifier will have enough current to drive the LED strip?  Can advise me on the model no? Thanks.

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: PIR Sensor with LED Strip
« Reply #7 on: February 11, 2012, 09:52:40 AM »
It is not that simple to say as you need to know the total current of the LEDs at maximum and the total power dissipation of the transistor at minimum. Generally, i think that a BD243 is be enough.