5pcs HC-SR501 PIR Infrared Motion Sensor Human Body IR Movement Detector Sensor Module for Arduino for Raspberry Pi

The media could not be loaded. After a couple of decades, I decided to build some new life size figures using some of the latest sensors, relays, and motors. I'm using the HC-SR501 sensors to initiate the animatronics, and found a couple of issues. They work w/o issue, and will continue their use. I also wanted to incorporate a flame bulb that will go in the medieval torch I built out of PVC pipe/fittings, EVA foam, and modelling paste.Regardless of the input voltage, the HC-SR501 output trigger voltage is only 3.3V-3.4V DC. This means I can only use 5V DC opto-relays, instead of 12V opto-relays as their trigger voltage is >4.5V DC. This required making a 5V circuit to power the HC-SR501 and the relays. The video shows the DC-DC Buck converters (blue LEDs) and the 5V DC opto-relays (red LEDs) driving the HC-SR501, one motor, and the flame bulb. The simplified schematic shows the wiring layout I made with applied voltages.The second issue to note with the HC-SR501 is the delay pot. It only takes a 10 degree turn of the pot to go from the minimum delay time of one second to 25 seconds.Their sensitivity is very good. I have yet to try adding a thermistor to the HC-SR501 to test its night time capabilities.FYI: I'm using the B0CMXCZX9Y nylon standoffs (via Amazon) to mount all of these boards.UPDATE: I'm holding back from installing a thermistor. Low light sensitivity is excellent.

As per the HC-SR501 data sheet, stops detecting ("detection range is shorter") as temperature approaches 30 degrees celsius (approximately 90 degrees fahrenheit). These units have the through-holes to add a thermistor to improve high temperature performance, if one has a thermistor to add.The real test is if starts detecting again when the temperature drops. I plan to drop my score one star for each unit that permanently fails on me.Worked just fine the first three days I had it connected. Easy to set up. Pins fit well into female Dupont wires for prototyping.

works as intended

Bien

So my fiancé had the idea to have a Shrek themed party and I thought it would be a great idea to have a speaker yelling at people 'WHAT ARE YOU DOING IN MY SWAMP'. So I bought these PIR sensors and hooked them up to my Pi 3 and programmed it to play a sound on detection. These are very sensitive so I recommend hiding them so they can only sense one direction.

Hooked up to 5V supply, output toggled from high to low as the description says, tweaked the pots on it to play with it, they work also. Now to figure out what the heck I want to use these with, I bought them for Halloween stuff.

I used one of these PIRs to activate a DC switching circuit, that I also got on Amazon, in order to control a linear actuator for a Halloween decoration. I used this PIR because it has adjustable timing.

So here's the thing, they work great; if they work at all. 3/5 of the sensors I received always either failed to detect any movement or constantly registered everything as movement. I decided to give it the benefit of the doubt and try and remove any possible interference and no dice. It wasn't until I tried my 4th sensor that things magically started working, and to be honest, I don't even know if the 5th one works as I'm too afraid to mess up my current setup.