At the local autopart store, they have these little "toys" that clip onto your car air vents. When you receive a call, the toy blinks or lights up. How does that work? I'd like to build one myself. Jeffrey
- posted
19 years ago
little car accessory that light up with cell phone usage
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- posted
19 years ago
when you cell phone is being called, the cell phone sends information back to the network. This a few watts worth of RF power. The 'toy' uses a filter tuned to the right frequency, and because the transmitter is very close by, there is enough power to light up a LED.