Wireless Motion Sensor Project

[o_silk_o]

This is my first post so HELLO!
I took electronics at school 4 years ago so have some knollege of electronics but im very rusty.
I have just taken up Airsoft and would like to make some devices for some of the games. The first device I would like to make is a wireless device to alert me when someone trips a wireless sensor.

There are to to parts to this project:
Part 1.
A small display that can be attatched to my wrist to silently alert me to the sensor is tripped. I was thinkig LEDs would be the best option. (I am thinking 4 LEDS for 4 sensors)
Part 2.
I would like 4 motion sensors. Very small. They just need to wirelessly activate the LEDs on my wrist when someone moves past the sensor. They will be used inside and outside.

I would like a good range for these but have no idea on what I can get away with! 500 meters including inside a stone building would be great.

Any help you could give me on this would be wicked!

Thank you for your time!

 

[Sceadwian]

You could use a simple IR trip alarm. A 'stupid' IR modulator placed at a single location and a receiver module that looked for that IR signal. If something walks inbetween the transmitter and the receiver it would know and you could send the information using a wireless module to your wrist display. I would't recommend LEDs though you should be looking at the field not your hand, the motor from a pager or old cell phone are perfect, if you use a low voltage you can't hear anything but you'll be able to feel it, perfect silent alarm. Not a quick and easy project though, good to get to know micro controllers, simple RF modules from sparkfun can be pretty cheap. Worth looking into. More than one sensor would require more receivers and possibly more 'beacons' Although if you aimed the LEDs right you could use a single beacon like a star, where the recievers are the points. You could use the vibrate for a beam break alert and status LEDs for each of the sensors. It could get relativly complex.

 

[o_silk_o]

Thank you for the quick reply! Building a vibration alert into the wrist pad is a very good idea. I wanted to mount it in the underside of the wrist that holds the gun so it woukd be visable. Do you have a ruff idea as to how small/big the 2 units could be? Also a very ruff cost in parts?
Thank you