I bought a $2 pack of assorted LEDs from Radio Shack.
None of them seem to light up, from 1.5v to 4.5v. I haven't seen LEDs that require Vf exceeding around 5v so I wonder if there are LEDs that go up to 9v or 12v forward voltage?
I might just sacrifice one of them to test on a 9v battery.
How do I figure out Vf of an unknown LED? I tried rigging up a circuit with a bunch of resistors in series but even without any resistors (max to 4.5v as mentioned above) no light from the LEDs.
And I tried both polarities.
Advice?
None of them seem to light up, from 1.5v to 4.5v. I haven't seen LEDs that require Vf exceeding around 5v so I wonder if there are LEDs that go up to 9v or 12v forward voltage?
I might just sacrifice one of them to test on a 9v battery.
How do I figure out Vf of an unknown LED? I tried rigging up a circuit with a bunch of resistors in series but even without any resistors (max to 4.5v as mentioned above) no light from the LEDs.
And I tried both polarities.
Advice?