Hi, I am working on a budget trail camera and am using a classic HC-SR501 PIR sensor. However, I’m getting a lot of false triggers. My basic research points towards shifting outdoor temperatures causing this.
Could you please help me identify a suitable PIR sensor for outdoor applications?
PC
Hi @Prithul271176 ,
The HC-SR501 PIR sensor that you are currently using has a potentiometer on the board that can be used to adjust the sensitivity manually, which is likely what would need to happen to compensate for temperature fluctuations.
Maybe an alternative PIR sensor that has an input for sensitivity adjustment would be more useful for your project. The following sensor is not quite as powerful as the HC-SR501, but it does have the ability to adjust the sensitivity from your controller, which could help account for the errors you are getting.
Hope this helps!
Hi @Samuel,
Thanks for your reply! The HC-SR501 potentiometer settings are at the lowest. I think I’ll give BS612 a shot.
PC
Hi, just a quick question (more like thinking out loud): I’ve used a lot of trail cameras that are simply excellent in detecting motion and subsequently taking pictures. One common link to all would be that their PIR sensor has a black Fresnel lens. I wonder if this (in contrast with my white lens) is what minimises false motion triggers in trail cams. I could be wrong as the black colour could simply be to camouflage.
Does the color of the Fresnel lens matter?
PC
Hi @Prithul271176 ,
That’s an interesting observation! I’m not sure exactly why the lens would be a different colour on a purpose-built trail camera, although I do have a guess. I wouldn’t be surprised if this black colour you can see is actually some sort of IR filter to prevent false readings like this.
A lot of trail cameras are marketed as having ‘no glow’ lenses, so this could also be something added in to make the lens reflections less visible to wildlife. Interesting stuff!
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