Here’s a cool little tiny wireless motion sensor you can make for the spies in all of us.
The idea was to put together a movie spy-gadget grade device both on the cheap and very small. Usually the gadgets you see in movies are fictionally created by well-funded government agencies with top scientists. It’s not all Hollywood magic – you too can create fun spy gadgets without needing to break the bank!
Ah, my old friend, the TX433. As seen on my wireless color-changing abstract decoration writeup, the TX433 transmits any signal over the 433MHz unlicensed radio band to the receiver. It’s currently available at the Canadian QKits, or you can find similar modules on eBay (look for 433 transmitter). These things are wicked awesome – they pack a whole lot of usefulness into a tiny, tiny package.
In my implementation, since the motion sensor only puts out a logic high pulse, I needed to use an IC to generate a sound when the motion is detected. This was accomplished with the HT12E Remote Control Encoder IC, but you can use a simple oscillator or sound effect IC or whatever you want. The idea is to make something audible so the receiver can pick it up. Hookup is easy – the HT12E just needs power and a resistor for its oscillator. The pulse from the motion sensor powers the HT12E encoder and the transmitter. This way the transmitter and encoder aren’t powered when they don’t need to be, saving mondo battery life.