Using an amplifier with a PIR sensor

[pic_programm3r]

hi,

i am having a problem detecting output changes from a PIR sensor module that is connected to a PIC, when the PIC detects the output changes it is suppose to respond by flashing an LED.
I measured the voltage and it was constantly outputting 64mV which i think is too small for a PIC to detect. I have heard that an Op-Amp is required to increase the voltage so the PIC can detect it.

I am not sure how to configure the op-amp and what mode of operation it should be in.
Please can anyone help me.

Thanks

 

[Nigel Goodwin]

Surely a PIR sensor module outputs a logic level of some kind, to activate a relay or something similar?. Do you have something different?, or have you connected it wrongly?.

 

[dknguyen]

Did you place a changing (or moving) heat source in front of it? A PIR sensor won't have any output for steady state conditions.

 

[pic_programm3r]

the output is connected directly to the port of a PIC. i have been putting my hand directly in front of it and havent seen any output changes. i thought because the voltage output level was so small that you couldnt tell the differance and thats where an amplifier came in.

 

[eng1]

Do you have a part name or a datasheet for your sensor? The manufacturers usually provide schematics including the amplifier stages.
As susggested, a PIR sensor module is far easier to use, as its output is TTL compatible.

 

[Nigel Goodwin]

You still give no clue as to what you have, a PIR module normally has a logic output of some kind, to feed a relay or an alarm system - are you wiring it incorrectly?, or do you have something different?.

 

[pic_programm3r]

this is the one i'm using:
https://www.futurlec.com/PIR_Module.shtml

hmmm......i think i have wired it correctly i measured the voltages and i was getting 5v of source voltage

 

[Nigel Goodwin]

So why not try reading the specification?

Voltage Output: High/Low level signal 3.3V
(Other choice: Open-Collector Output)

Is your's the optional open-collector output version?, if so add a pullup resistor from the output to +ve.

 

[pic_programm3r]

Got it working today!
It was just a simple program code error. i had configured the PORT in the microcontroller that the sensor was connected to incorrectly.

 

[Gayan Soyza]

I'm thinking why you need a micro controller for this to flash a led on output.

Did you see the diagram that operates a relay on the last page without using microcontroller?

 

[pic_programm3r]

its because i'm testing the sensor for a microcontroller based project i'm working on.