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I'm trying to build a simple SRIX4K emulator using an ATMEGA328p, I found this circuit on the internet, and it should work as a simple ASK transceiver, using the MCU to transfer data using the SRIX4K protocol:
https://github.com/Ptr-srix4k/SRIX4K-Emulator/blob/master/Manual.pdf

I tried to both simulating (using this website: https://www.falstad.com/circuit/) and building it with no luck, I'm unable to get the antenna to resonate with the circuit.

The POC containing this circuit: https://github.com/Ptr-srix4k/SRIX4K-Emulator/blob/master/Manual.pdf

How SRIX4K protocol works: https://media.digikey.com/pdf/Data%20Sheets/ST%20Microelectronics%20PDFS/SRIX4K.pdf

Any help or suggestions would be highly appreciated.

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  • \$\begingroup\$ Where's the power transferring transmitter situated? \$\endgroup\$
    – Andy aka
    Commented Dec 1, 2023 at 15:12
  • \$\begingroup\$ there isn't one, the circuit is powered by a battery \$\endgroup\$
    – Giovanni Visentin
    Commented Dec 1, 2023 at 15:21

1 Answer 1

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I'm unable to get the antenna to resonate with the circuit.

Where's the power transferring transmitter situated? – Andy aka

there isn't one, the circuit is powered by a battery – Giovanni Visentin

You need an externally generated AC magnetic field that drives the coil: -

enter image description here

So, when you say this: -

I'm unable to get the antenna to resonate with the circuit

It gives me the impression that you expect your circuit (as shown in your question) to oscillate happily on its own. That won't happen. The lower circuitry attached to the coil is an envelope detector for receiving AM data that is embedded into the externally generated magnetic field. The upper part of your circuit (Q3) can modulate the received externally generated field and, this modulation can be received by a sensitive detector within the external generator.

Any help or suggestions would be highly appreciated.

You need an external field generator to make this work.

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  • \$\begingroup\$ If I understood correctly, I simply need to put the emulator on the reader to get the antenna to oscillate? i have a pn532 rifd reader that supports SRIX4K protocol and works on the same frequency, could that do the job? \$\endgroup\$
    – Giovanni Visentin
    Commented Dec 1, 2023 at 16:20
  • \$\begingroup\$ @GiovanniVisentin If the receiver antenna coil inductance resonates closely with the applied external magnetic field from the reader then it should work but, your MCU has to work with that protocol and have no bugs. \$\endgroup\$
    – Andy aka
    Commented Dec 1, 2023 at 17:32

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