About RFID card reader operating frequency

Discussion in 'General Electronics Chat' started by Kardo22, Jan 23, 2015.

  1. Kardo22

    Thread Starter New Member

    Mar 12, 2014
    I have a problem with a RFID card reader with U2270B. Some don't recognize the card at all and some only do at very short range.
    I measured the frequency at RF and coil output pins and the results were:
    the working one - 122kHz
    the one working at short distance - about 116kHz
    not working - about 100kHz

    What could change the frequency and is it possible to find out. All resistors seemed correct but I can't measure capacitors, can I find out somehow where the problem lies?

    U2270B - http://www.bdtic.com/DataSheet/ATMEL/U2270B.pdf

    The circuit is something like attached picture (untitled).
    edit: added picture that is closer to my schematic but standby pin is grounded like in picture 2.
    Last edited: Jan 23, 2015