SB00622A-2 from Alexan is the cheapest body motion sensor I've bought, it can be autonomously or stand alone detects motion if 3.3v-15v power is connected. It's also easy to use and operate, if you have background in micro controller like arduino you can also use this for fun projects. It has 3 pins for supply power and at the middle called “test” or output to microcontroller or arduino, while the other 2 pins can be use to power directly your LED, motor, and buzzer as alarm. I tested it with a motor and it works fine but I think it was not safe to that even it has resistors.
It also got 2 adjustments, one for light sensitivity “lux” if you are going to use them by night or daytime, the other one is called delay time (2 mins. to 70 mins)to adjust the alarm time. In its datasheet detect length is around 5 to 6 meters, but it only works for 3 meters when I tried it. The detecting angle is 120 degrees Im not familiar with this angle thing and not all angle was detected, there's some spot that detected my motion and some doesn't.
This little circuit's application can be used for fun and for security. You can make tricks to innocent victims by making loud noise while hiding the fresnel lens, or blind them with you high powered LED's.. but it's main purpose is using them to secure your house or vehicle to from bad elements around you, learning it's sensitivity might get rid of false alarms. More complicated or custom alarms to your computer or cellphone can be done through the use of micro controllers or arduino, you can do it by yourself by searching online tutorials or wait for my future fun project with it. This circuit is a must have to those who want's to safeguard their place or property.