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Is there such a thing as an inverted zener diode?

  1. Jan 20, 2012 #1
    Zener diodes act like regular diodes, except that they allow current to flow in the reverse direction if the voltage is high enough. That is, current with voltage ABOVE a certain value will flow.

    My question is, is there such a diode that only allows current to flow if the voltage is BELOW a certain level?
  2. jcsd
  3. Jan 20, 2012 #2


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    Staff: Mentor

    A fuse? (well, fuses are based on current and not voltage...)

    Or maybe Raychem's Polyswitch? (same caveat, though...)


  4. Jan 20, 2012 #3


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    Science Advisor
    Gold Member

    Think about what you are saying. Anything that allows current to easily flow will not likely allow a voltage to build up across it. So Berkemans suggestion of a fuse is pretty close to accurate. You could consider a wirewound resistor also. When they are over heated (too much current) they open up instead of sit and smoke.
  5. Jan 20, 2012 #4
    A linear voltage regulator will hold output to a set maximum voltage, and if the input falls below Vreg, power will continue to flow.

    A basic 3-terminal regulator can be used without any additional components, so it's really no harder to use than a Zener diode.
  6. Jan 21, 2012 #5


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    Staff: Mentor

    No, not a single semiconductor device. But you can build a circuit to do this, it has over-voltage cutout.
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