Anonymous
Mar 23, 2026
Rating: 4/5
Solid performance
Works as expected for a passive infrared sensor. It doesn't detect motion through glass, which is physics, not a defect. The output voltage is stable at 3.3V, perfect for microcontrollers.
Description
Reviews
| Brand | - |
| Category | Robotics / STEM Teaching Tools / Sensors |
| Origin | - |
| Model Number | HC-SR501 |
| Operating Voltage | DC 4.5V - 20V |
| Detection Distance | Up to 7 meters |
| Detection Angle | < 100 degrees cone angle |
| Trigger Mode | L (Repeatable) / H (Non-repeatable) |
| Delay Time | Adjustable from 5s to 300s |
| Blockade Time | Fixed at 2.5 seconds |
| PCB Dimensions | 32mm x 24mm |
| Working Temperature | -15°C to +70°C |
| Output Signal | 3.3V TTL High/Low |
Anonymous
Mar 23, 2026
Rating: 4/5
Solid performance
Works as expected for a passive infrared sensor. It doesn't detect motion through glass, which is physics, not a defect. The output voltage is stable at 3.3V, perfect for microcontrollers.
Anonymous
Mar 20, 2026
Rating: 5/5
Great for learning
Used this for my final year project. The documentation online is plentiful, making it easy to interface with Raspberry Pi. The delay time adjustment is a nice feature to prevent false triggers.
Anonymous
Mar 12, 2026
Rating: 5/5
Perfect for Arduino Projects
This sensor works flawlessly with my Arduino Uno. The sensitivity adjustment pot is very responsive, and I was able to dial in the exact range I needed for my hallway light project. Great value for the price.
Anonymous
Mar 07, 2026
Rating: 4/5
Good sensor, needs calibration
The module arrived quickly and looks well-built. It took a minute or two to initialize after powering up, which is normal for PIR sensors. Once calibrated, it detects motion reliably. Just make sure you give it the correct voltage.
Anonymous
Mar 07, 2026
Rating: 5/5
Exceeded expectations
Very sensitive and accurate. I set the delay to the minimum for a quick test, and it reacted instantly to movement. The screw terminals are not present, so you will need to solder headers, but that's standard for this type of module.
Anonymous
Mar 04, 2026
Rating: 5/5
Reliable and Cheap
I bought five of these for a security prototype. All of them worked out of the box. The detection angle is wide enough to cover a standard doorway. Highly recommended for DIY electronics enthusiasts.
Q: How long does it take for the sensor to initialize after power-on?
A: The sensor requires an initialization period of approximately 30 to 60 seconds after being powered on. During this time, it may output high signals intermittently; this is normal behavior.
Q: Does this module come with header pins soldered?
A: No, the module typically comes without pre-soldered headers to allow for flexible mounting options. You will need to solder your own 3-pin headers to connect it to a breadboard.
Q: What is the difference between L and H trigger modes?
A: In L mode (repeatable), the output stays high as long as motion is detected. In H mode (non-repeatable), the output goes high for the set delay time once motion is detected, ignoring further motion until the cycle completes.
Q: Will this sensor work outdoors in the rain?
A: The PCB itself is not waterproof. For outdoor use, you must house the module in a waterproof enclosure while ensuring the Fresnel lens has a clear view.
Q: Can this sensor be powered directly by a 5V USB power bank?
A: Yes, the HC-SR501 operates within a DC 4.5V to 20V range, so a standard 5V USB power source is perfectly suitable.