IR Infrared Motion Detection Sensor Module (DC 5V~20V)

Pros: Very small - you can set it up everywhere. Can use low voltage power - even USB Have 2 resistor for tune in sensitivity. Price is affordable.

Cons: Board could be smaller If device so small - they should use SMD capasitors It would be great to have digital in\out on it - I2C or rs232. 1 on\off pin is good, but not enought.

Other: This device can be used as base of your security in your home. Just collect signal wires from all sensors to easy to program Atmel or microchip controller and you can trace everyones who move in your home.

Pros: Cheap, configurable timing and sensitivity

Cons: Packaging/shipment: the pins and capacitors were bent when the package arrived, that why I didn't give quality the 5 stars.

Other: Great if you want to experiment with motion activated Arduino projects.

Pros: Very good Price. I have ordered these from other electronics suppliers for about $10 a piece. My application is to use these for turning on lights. When triggered it will slowly bring up accent lighting and when the sensor isn't triggers the lights will slowly dimm.

Cons: Doesn't has a CDS cell for to disable operation when ambient light levels are high. One option for a lense that will not trigger by pets is not availible on DX

Other: Good price, good quality

Pros: Easy to use motion detector with variable sensitivity and variable output-High time (2 sec ... few minutes). Output High-Level is 3,3 V, an 1k resistor is already on the board so you can connect the base of an Transistor or a LED directly to the output.

Cons: The Ti-Time (During this time period, triggering is inhibited) was to long (approx 3 sec) for my application. I changed R12 (1 Meg.) to 100k so the inhibit-Time is now approx 0.5 sec.

Other: Can be used with a camera to build a camera-trap!

Pros: There is all documentation for it: HC-SR501. You can connect CdS light sensor in it. It has two potentiometers and jumper pads so you can setup to suit your needs. The plastic lens is removable, so you can fit another or fit it differently.

Cons: no light sensor, but you can put a Cds in it, it has free holes for it, go for R3

Other: Unbeatable must have for the price. Even if you don't have use for it now, you can learn everything about PIR technology on it without fear of blowing something expensive.

Pros: Very cheap and relient item. I am surprised as sensitive it is. I like it and would order more for other projects involved motion detection.

Cons: No cons at all. May be one - you have to ajust two rotating resistors to have time and sensitive you need. But in fatc I think this is not cons but rather pros beause you cand ajusta it to you project precisely.

Other: Would recommend it.

Pros: It's very good and easy to use. It's very sensitive and can work within 2 meters as far as I've tested it.

Cons: Not a con, but it's not ideal to use in small spaces. It would be ideal to put it in a room and it will trigger whenever someone goes inside. Because it measures the change in the background temperature to sense a moving object.

Other: Get it if you like to play with motion sensors.

Pros: Very cheap and relient item. I am surprised as sensitive it is. I like it and would order more for other projects involved motion detection. Easy to use motion detector with variable sensitivity and variable output-High time (2 sec ... few minutes).

Cons: Doesn't has a CDS cell for to disable operation when ambient light levels are high. Board could be smaller If device so small - they should use SMD capasitors It would be great to have digital in\out on it - I2C...

Other: Good price, good quality

Pros: Very sensitive and easy to use. It's also configurable using the two pots it comes with, which can also easily be replaced with a digital one (or two)

Cons: Would be nice if a datasheet was available. But you don't really expect that from these kinds of assembled components.

Other: Works very well and is cheap. Get one even if you don't need it immediately. Even if you don't find a use for it later on, they're fun to play with ;)

Pros: It's a product of a nice quality and very easy to use for people which are getting started on arduino. I found some examples on internet and started to use it inmediately

Cons: Its design could be better (capacitors do not let you install it at the center of protoboard) and It doesnt have instructions, but i searched for them on the internets

Other: I recomend this product for arduino starters because it is very easy to install and learn