5 Pack HC-SR501 Pir Motion IR Sensor Body Module Infrared for Arduino

Hooked the VCC and ground to a 12v A/C adapter and it worked perfect. The 3.3v "trigger" pin (the "OUT") even had enough juice to directly power a red LED (tho a little dimmer than normal). Very wide sensitivity pattern. Tho description says "< 100 degrees" I thought it was greater than 120. At default sensitivity it would trigger easily from 8-10' away. I never adjusted it as that was the perfect distance for my needs. Holding it with the sensor "dome" facing down and the adjusting (orange) "screws" facing you, the left one is the sensitivity, the right is the duration that the OUT pin will stay "on" (i.e. hold at 3.3v). Minimum seems to be around 4 seconds.

So far I have used two of these and both worked right of the bat. Very easy to hookup with ample code available on the net. I have these hooked to an ATTINY85 programmed to turn on when motion is detected. I used Pin7 as the light output which goes straight to a 2N2222 via a resistor. The transistor accepts the signal, turns on and activates a relay which the lights are connected to through COMM. Love um....a lot of fun to fool with.

These work great, and are easy to hook up and adjust. One of the five didn't work, but for the price I still think its a great deal. Buy more than you need, as you can find lots of uses for these guys in animation and robotics. They really made my Halloween props come to life!

Only 2 worked out of the 5... Changing to 5 stars! The company contacted me and arranged for replacements. The new ones all function. I may had a bad batch originally. So I would recommend this product and the company for following up.

My first impression is that these are great little sensors. They seem to detect motion well and hookup is really easy. They work perfectly to drive the 5 volt input of a relay module; when I get time to experiment I'll see what they can really do.

I'm providing a middle rating because documentation is not good. I don't know if I misread the specs when I purchased but I thought these PIR sensors would work with 3.3v input/source voltage and output 0v low and 3.3v High on output. I now know that they certainly need 5v source input voltage and output 3.3v. When I provided 3.3v input power they acted erratically and would not go predictably low. Using 5v input the 3.3v output consistently dropped low to 0v. In Summary: 5v In = consistent 3.3v out when triggered, and 0v when clear/not triggered.

I first bought a pre-built 'smart' light switch with a motion sensor that was WAY too sensitive and couldn't be adjusted. I decided to go the DIY route and bought these. I connected one to a NodeMCU, which I set up with Home Assistant using MQTT (along with a simple 'smart' switch sans motion sensor). It's awesome, gives me so much more control and cheaper. I do get some false-positives, but not nearly as much as with the pre-built unit. I suspect it's due to being in the garage and the sensor picking up sunlight/shadows coming in through cracks in the garage door. Overall, very happy with the purchase.

This product is perfect, and I love that it has a delay. I can wire this up to a board as-is without building a delay circuit myself. I've been using one continuously for a few weeks, and it's very responsive with a nice range. It has pretty good depth, but I haven't tried to press it. It can spot motion across an entire (average) room easily. I have projects lined up for the other ones included in this pack, and if I need more, this is where I'll get them.

These are useless as motion detectors due to the false reports. Yes I tried the pF capacitor from Signal to Ground and I shortened the signal wire. It did reduce the false motions but they still happen few minutes. Unfortunately I can't send them back due to adding the capacitor to the circuit. I would not recommend these to anyone. I will try to keep fussing with them. I am trying now on a Wemos D1 Mini with less than 1 cm of signal wire from PIR to data pin. UPDATE: Still bad on the wemos with <1 cm wire. Tried pull up resistor - no effect. Increased and decreased capacitor size - no effect. I've ordered a different type. Hope they work.