What is the minimum voltage required to turn on a diode ?

Question

What is the minimum voltage required to turn on a diode ?

Answer 1

I'm gonna say 5-6 volts, but it seems they are popping up more in the automotive world, and are having issues with the standard 12 volt systems, especially when designed as hazard flashers, tail lights, back-up lights, etc...

Apparently they require some special relays for proper operation...

I used to stick them on 9v batteries to light 'em up as a child. :D

Answer 2

Depends on the diode, what voltages it was designed for.

Like I said:

http://www.st-andrews.ac.uk/~www_pa/Scot...

http://www.interq.or.jp/japan/se-inoue/e...

http://books.google.com/books?id=Vl8naJH...

Answer 3

A lot of wrong answers.

At low to medium currents, VF = 0.6-0.7 for a silicon diode, and 0.3-0.4 for Geranium diodes. The latter are rare.

At higher currents, the drop increases because of ohmic losses, so you may see 1 volt or more.

At reverse voltage ratings much above 1000 volts, diodes are actually several junctions in series, so the VF goes up.

.

Answer 4

The minimum potential is the Depletion potential of the diode.

It is usually 0.7 V for a silicon Diode and 1.1 V for Germanium diode

Answer 5

It varies with the particular diode. Out of 10 U may have 5 that are very closet ,but they can very quite a bit. Silicone's are very near the same but the Germanium can very even moor...

Answer 6

And there's the Schottky diode with a Vf of 0.15-0.45V

Answer 7

At any forward voltage, some current will flow, but until the depletion potential is reached, the forward current vs. voltage will be comparable to the leakage current that flows when voltage is applied in the reverse direction. Once the depletion potential is reached, the diode can be considered to be "turned on" and the current will be essentially limited only by the power source. The forward voltage will rise slightly as the current increases. A silicon diode might have a depletion potential of 0.7 volts and a forward voltage drop of 1.1 volts at the maximum rated current. Typical values would be less for a germanium diode. Actual values will vary depending on device specifications and from sample to sample of devices with identical specifications.