Simple PIR sensor?

Hello everyone,

I'm having hard time finding ideal PIR sensor for my project. I need small PIR sensor that works reliable. It doens't have to be very sensitive, but I don't want false alarming.

Currently I tried:

  • HC-SR501 - it works great but it is huge
  • HC-SR505 - it is smaller but still large for my project
  • AM312 - it is small but gives false alarms

First of these two PIRs are pretty large because I want to make just one small custom board and have only PIR element soldered on it. If I use PIR elements like D203S or RE200B I need to have detection circuit and that uses additional space on my board.

AM312 looks great because it has detection circuit built into PIR element. It only requires 3V and outputs 3V if motion is detected. That is great but looks like I'm having some false alarming with this sensor. I'm looking for similar sensor but more reliable, any idea?

I cannot find a datasheet for the AM312 without having to request it but maybe you should investigate what is causing the false triggers and fix/filter them out. Maybe it's an inherent problem with the sensor or maybe power supply glitches causing the trigger.

You can find datasheet in attachment.
I designed power supply circuit identical to instructions in datasheet. But still get few false triggers in one hour.
I’ll try to add more decoupling capacitors near PIR element and see if it solves problem.

This project also uses ESP-12E WiFi module, could it be that WiFi singal is interfering with PIR sensor?

Pir-AS312.pdf (438 KB)