Is there such a thing as an inverted zener diode?

[warfreak131]

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?

 

[berkeman]

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?

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

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

http://www.te.com/en/products/circu...nt-devices/polyswitch-resettable-devices.html

.

 

[Averagesupernova]

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.

 

[pantaz]

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.

 

[NascentOxygen]

My question is, is there such a diode that only allows current to flow if the voltage is BELOW a certain level?

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