Hi All,

I spent the last two days on trying to condition the signal of a PIR sensor - D203S - on my breadboard without luck. I was following the circuit described on https://www.st.com/resource/en/appl...e-infrared-pir-sensors-stmicroelectronics.pdf however it's not working for some reason.

My question is that anyone had any luck getting PIR sensor working on breadboard? I heard it's very noisy, so was thinking it might be the reason I'm unable to get this circuit working

Thanks

 

Hi kz,
Which type of Fresnel lens are you using?
E

 

Hi kz,
Which type of Fresnel lens are you using?
E

Sorry, but not sure. Its only a cap with a holder and it holds the sensor firmly. Looks like it has the same pattern of lenses all around. Sorry if its not much help.

 

Hikz,
A regular PIR sensor relies on the Fresnel lens in order to create a low frequency signal voltage.
Look at this PDF, note the pattern created by the lens.

Please post a photo of your PIR project board.
E

 

Please post a photo of your PIR project board.

Sorry, will have time to re-check over the weekend only. Will report back. Thank you

 

A Fresnel lens has dimples all around the cover , in different directions, does yours look similar to this?

 

A Fresnel lens has dimples all around the cover , in different directions, does yours look similar to this?

View attachment 317754

Yes, its like this one

 

Yes, its like this one

Okay, can you post pictures of the breadboard, all directions,and the circuit diagram you're working from?

 

Okay, can you post pictures of the breadboard, all directions,and the circuit diagram you're working from?

The circuit is in the pdf I linked in the original post (https://www.st.com/resource/en/appl...e-infrared-pir-sensors-stmicroelectronics.pdf), will take some pictures but not at home till late tomorrow.

 

Does the TS have anything to examine the waveform of the IR device and the voltages within the circuit? Consider that attempting to do any diagnostics with no information is depending on a very lucky guess, we do need to know what resources the TS has available.

 

Does the TS have anything to examine the waveform of the IR device and the voltages within the circuit? Consider that attempting to do any diagnostics with no information is depending on a very lucky guess, we do need to know what resources the TS has available.

Ok.. fair point, sorry did not put this info earlier. So I have a handheld scope and tried to check the signal while providing 6VDC to the circuit. I measure ~700mW after sensor and after stage 1 / 2. I can also see a 160-320mW pp noise. so maybe the sensor is working, but I have too much noise so cant really see it. Will take a picture of scope output too. Thanks

 

Seems like its a faulty PIR sensor after all. I had 3 of them, tried two - same result. I tried the 3rd one now and its working… Now Im thinking how did I blew the other two… Can I damage it if I “forget” to put a current limiting resistor and connect it directly to VCC?

 

hi ks,
Look at page #4 of that PDF I posted, you require a series resistor.
As you have guessed, you have most likely blown the two sensors,
E

 

hi ks,
Look at page #4 of that PDF I posted, you require a series resistor.
As you have guessed, you have most likely blown the two sensors,
E
View attachment 317829

That must be it. Thank you all!