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Some advice on an RFID idea i have? Answered

Realistically, how difficult would it be to DIY a passive RFID system where the tag simply reacts by lighting a low power LED. Catch is, i would want it to have an effective range of at least 1m. Could i build the EM emitter myself, or would i have to buy a high power reader?


Not difficult at all for the 'tag lighting up an led instead of responding with a code'

Somewhat difficult is the 'get it to work at a meter distance' -- without a pretty big/directional reader/transmitter or a VERY well tuned transmitter you won't get 1m distance

You could build all of the above yourself. If you just want power from A to B and not any data transfer, then you want just inductive coupled coils. Generally if you build 2 identical coils and put AC into one the other should react with some current. The frequency/voltage required will vary based on the coil and distance required.

You CAN do inductive data transfer over the same channel, while you are transferring power. Its not hard.

Indeed, it's how most-all rfid systems work - powering the iC almost as a byproduct of the data stream. I never said it was impossible or difficult to get the data across, just that if a person ONLY wanted to light an led then it simplifies things since you can ignore the data's requirements and just stick to the power coupling ;)

Well it's solely the power coupling aspect i'm after. How could a directional emitter be designed, as i imagine this would help with the 1m requirements.

This is my first attempt at RFID, so a great amount of crash coursing going on atm :D