Matrix Keypad with MT8870
Last Post 15 Apr 2013 08:39 AM by jwd217. 1 Replies.
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Mridul Agarwal
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13 Apr 2013 07:26 AM
    I have a circuit which have two wires for input , so can anyone tell me how to connect a 4*4 Matrix Keypad with it . Circuit can be found at:-
    New Member
    New Member

    15 Apr 2013 08:39 AM
    This circuit expects to have the keypad tones of a typical phone key pad entered on the input labeled "TIP" with "RING" being common. If the Matrix Keypad you have does not produce the phone keypad tones then you would need add that capability.

    Wikipedia has an article titled "Telephone kaypad" that list what frequenies those tones are.