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Thread: Input protection for a frequency counter (or any other gear for that matter)

  1. #1

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    Default Input protection for a frequency counter (or any other gear for that matter)

    I'm planning to use a couple of zener diodes to protect the input of a frequency counter kit I built a while back. However, I've seen several ways of doing it - see the attached drawing for A, B, & C.

    Any ideas what is the best way?
    Attached Images Attached Images

  2. #2
    Super Moderator 5B4AJB's Avatar
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    Inductive coupling?

    A few turns of wire wrapped around the through connector line should do it...

  3. #3

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    Never though of that one. Thanks.
    So, I guess I would shunt the input sign to earth via a load resistor? 1 M?

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    Super Moderator 5B4AJB's Avatar
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    You mean 50Ω?

  5. #5

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    Quote Originally Posted by 5B4AJB View Post
    You mean 50Ω?
    That's what I first thought, but since the counter is 1 Hz to 50 MHz, it doesn't necessarily mean it will be plugged into a radio.

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