Help with PIR Sensor

[awilder]

I have a passive infrared sensor from Radio Shack. I have tried to wire it up to a small buzzer. However, I have had no success getting it to work.

I thought I could just attach the battery source to the (+) and (-) leads and then attach the buzzer to the (out) and then back to the (-). When movement is detected it should send voltage through the (out) pin. Instead, the buzzer just goes on and off every 2-3 second, even when nobody is near the sensor. I have also tried giving the sensor time to stabalize.

I connected the (-) and (+) and positive leads from the sensor to two AA batteries. I then used a multimeter to check the voltage coming from the (out) lead. I connected the multimeter to the (out) and the (-) leads. What I get is about 2-3 volts showing on the multimeter every few seconds. The voltage just pulses up and down from 0-3 volts every 2-3 seconds. Movement has no effect on the PIR sensor at all.

Can anyone tell me what I'm doing wrong?

 

[ericgibbs]

hi,
Whats the PIR part number.? or datasheet.?

 

[Reloadron]

I believe you have a Radio Shack Catalog #: 276-033 which is actually a Parallax PIR Sensor (#555-28027). This should be the data sheet for your sensor.

The sensor is designed to work from a minimum 3.3 volt supply with a maximum of 5 volts. Likely your batteries are not adequate (2 x 1.5 volts = 3 volts). Additionally I don't know how much current these units can drive but I would venture a guess if you want to drive a buzzer of any substance you will need to do it using a transistor. PIR to Transistor To Buzzer.

I would start by using 3 batteries to power the unit with about 4.5 volts. See if it works with a voltmeter looking at the output. See how much current your buzzer requires.

Ron