Scratch-built RFID reader

We never bought an RFID reader because it seems too simple to be all that much fun. But [Abdullah] really caught our eye with his latest project. It’s an RFID reader built from discrete parts, and that’s an adventure we can get behind!

His write-up dives right into the theory of the device. He wrapped his own coil, which measure about one microhenry, then shares an equation used to calculate the appropriate capacitor pair for it. This is fed by a 125 kHz oscillator and works as the most basic reader. In practice this needs more components for rock-solid operation and he quickly moves to a marginally more complicated circuit which still does exactly the same thing.

He is now able to detect RFID tag data by reading this circuit with an oscilloscope. But the signal is very very weak. The rest of the post focuses on how to best utilize an OpAmp to increase signal quality and on/off time.

If you’re looking to recreate his reader [Abdullah] included a Kicad schematic and board layout.

Comments

  1. welshmullet says:

    I’ve always wondered if you can do 2-way with rfid. Has anyone done it?

  2. Oodain says:

    looks interesting, i always liked the inventory system used in some factories, they can literally scan every sigle item on a truck while its driving through the gate

    is there a BoM?

  3. mstone says:

    Small typo in the writeup above: He states the coil being about one millihenry, not one microhenry.

  4. YS says:

    I’ve made the same thing using parallel RC-circuit, but failed to decode manchester coded data…

  5. bothersaidpooh says:

    Combined RFID and wireless power would be handy.
    I was looking into this for my electric bike, so it could be secure and remote charged via a paddle without physical connections to the battery.

  6. kabukicho2001 said, says:

    See a pic of simulation at /media/0C28-ECA9/REC142.WAV

  7. kabukicho2001 said, says:

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