how does this work?

Thread Starter

bug13

Joined Feb 13, 2012
1,788
Hi guys

I come across this little transmitter only tag, I am just curious how it may work. I am guessing the pic (12f629) send out some kind of on/off keying to the oscillator, and the receiver decode those info.

Another question is how can they make the antenna so short?? it's 433MHz transmitter!!

Thanks guys

IMG_3544.JPG IMG_3545.JPG
 

Thread Starter

bug13

Joined Feb 13, 2012
1,788
Hello,

Did you see L2 on the PCB?
That is part of the antenna making it longer.

Bertus
I thought that might be the case, what do I need to google to read more about this? eg how to decide what inductor to use to make a Xmhz 1/4 wave antenna into Ymm??
 
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