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Re: 1802 oscillator problems

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  • nils_eilers
    Thanks for your help! ough... on the board, I hard a short between pin 40=Vdd and pin 39=XTAL, whereas on the breadboard I connected the wire with pin 2=WAIT
    Message 1 of 5 , Mar 1 8:55 AM
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      Thanks for your help!

      ough... on the board, I hard a short between pin 40=Vdd and pin
      39=XTAL, whereas on the breadboard I connected the wire with pin
      2=WAIT instead of pin 1=CLOCK...

      A few hours of sleep may change the world :-)
    • Allison Parent
      ... assuming it s wired right and the resistor is indeed 10M (1*10^6) ohms the first place I d go is a new crystal. remember it s a quartz wafer in there and
      Message 2 of 5 , Mar 1 10:08 AM
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        --- In cosmacelf@yahoogroups.com, Lee Hart <leeahart@...> wrote:
        >
        > nils_eilers wrote:
        > > My problem is: the oscillator doesn't run. I build according the
        > > datasheet with 2 MHz Crystal, 10 M Ohm and 2 x 22pF.
        > > Is this a known problem?

        assuming it's wired right and the resistor is indeed 10M (1*10^6)
        ohms the first place I'd go is a new crystal. remember it's a quartz
        wafer in there and it will shatter like glass if dropped.

        Allison

        >
        > Normally, the 1802 oscillator is no problem. Things to check:
        >
        > - what supply voltage? To run at 2 MHz you will need about 5v
        > (not 3v for example).
        > - is the crystal any good? will it oscillate with a regular 4069
        > inverter?
        > - is the 1802 good? You can test the internal inverter that makes
        > the oscillator by just wiring the input high, and seeing if the
        > output goes low, and vice versa.
        >
        > --
        > Ring the bells that still can ring
        > Forget the perfect offering
        > There is a crack in everything
        > That's how the light gets in -- Leonard Cohen
        > --
        > Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
        >
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