Electrical Engineering Stack Exchange
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Questions tagged [pir]

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.

The PIR (Passive-Infrared) sensor functions in the same way as an outdoor light with a motion detector and reacts to movements made by objects that radiate heat (people and animals). The switching threshold can be set from between 0% and 100%.

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A few questions on PIRs and other motion detectors

I grew up incorrectly believing that motion detectors (as part of burglar alarm systems) were designed to detect movement, when in actual fact it is the movement of a heated (like body heat) object which causes them to trip. I also understand there…
questioner
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Troubleshooting Strange Circuit Behaviour...Missing Diode?

I've built this circuit to control a submersible pump with a PIR sensor. The circuit works as expected (the PIR sensor activates the mosfet, turning the pump on) but only after about 30 seconds from when power is initially turned on. Before that…
Seano
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How can I amplify PIR output to 5V

I need help with a project. I want to make a circuit to work as a night-time motion detector circuit that will power several LEDs. I bought: 1 LDR some NPN transistors BC547 and 2N3904 some resistors 100kOhm boost regulator 3V to 5V PIR sensor I…
panayiotis kasapis
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PIR sensor always gives HIGH

This is my first time to use PIR (HC-SR501 ) . It's in repeat trigger model. But when I test the output of the PIR , it gives always HIGH . I rotate sensitivity adjustment and time delay adjustment randomly to see any changes occur. I even cover…
Anklon
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XBee and PIR sensor

I've ordered XBee wireless transceiver and PIR (motion, here is link) sensor. When I enable DIO0 digital input port on XBee with "ATD0 3" command it becomes high. I measure it with volmeter and get value of 3.3v. Same with PIR sensor, when motion is…
Volodymyr Smirnov
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Faster PIR Sensor speeds?

I am trying to use an array of sensors to trigger a series of stepper motors based on peoples' presence within different areas of a hallway. It is for an interactive kinetic art piece at an elementary school. I've tested with ultrasonic sensors,…
user2418372
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PIR Detector Controller IC

Honestly, I have a good deal of questions so this may not be for the faint of heart. I will do my best to ask them in a logical order with specific language. I really appreciate the helpful answerers out there. My questions are related to many…
fadfjnbkljkzlzp
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Need help building simple burglar alarm circuit

I'm trying to build a simple burglar alarm circuit and I've found one online that uses a knife switch, 9 V power source and an SCR. I'm trying to change it over to a PIR motion sensor but am unsure whether the mechanics are the same. Attached is a…
cwhitehouse
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Understanding analog frontend for PIR sensor

I read this application note from Texas Instruments to learn something about the design of an analog frontend for PIR sensors, but I don´t know the function of the first OpAmp circuit. What is the purpose of the two diodes in the feedback loop of…
Kampi
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Motion sensor to detect birds and small animals but ignore humans

I would like to develop a motion activated sprinkler to deter birds (cranes and other smaller birds) and small animals from eating the fish in my pond. I am using the approach of controlling a solenoid valve via a PIR motion sensor. However, this…
SamuraiJack
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thermistor in HC-SR501 PIR

i know the effects of soldering photo-resistor to HC-SR501 PIR module. It then detects movement in the dark only. But can anyone tell me that what is the effect of adding a thermistor to the same PIR module? There is a provision in module itself to…
Milind
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Convert 2s pulse into short pulse to wake up ESP8266

I have an ESP8266 that does something, then goes to sleep. I also have an AM312 PIR sensor which wakes up the ESP when activated. The PIR generates a 2 second long pulse when activated. The ESP wakes up when RST pin goes low. I use the PIR output to…
codemonkey
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Are the PIR sensor modules motion sensors or proximity sensors?

I wanted to make a small project in which the lights of a room can only be turned on when there is someone in the room and it will turn off in absence of any person. I thought of using PIR sensors but from what I read it looks like they sense motion…
Vibhore Jain
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PIR sensor not triggering P2N2222

I have this setup where a PIR sensor (HC-SR501) powers an LED strip with the help of a P2N2222 transistor. I then manually connected the Transistor base to the 12v rail and it has no problem powering the LED strip. I have also tried changing the…
Kokachi
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Different ways to detect seals?

I would like to build an underwater mammal detector to take videos of seals when they get in and out of their cave (the entrance of their cave is underwater). It will be a waterproof sealed box with a camera in it, fixed on the rocks (underwater, in…
arthur.sw
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