UV LEDS question

[eyevancsu]

what is needed to power a 5mm UV led?<p>please let me know,
thx, ivan

[russlk]

It is best to use DC. The "on" drop of the LED is about 1.6 volt, so use a series resistor of (vdc-1.6)/I where I is the rated current of the LED. If you don't know the rated current, use .02 amp. Apply + to the anode. If the leads have not been cut, the shorter one is the anode.

[L. Daniel Rosa]

You'll need at least 3.2 volts (with some variation) for the LED, plus a little extra for the current limiting resistor. If you use a 9V battery, use a 300 ohm resistor and that'll give you about 20mA.