No they aren't. They might be 3.4V.
They are anywhere from 2.9V to 3.8V.
Your 60 ohm resistor will overload the 2.9V LEDs and cause the 3.8v LEDs to be dim.
Try it again with only two LEDs in series with another resistor.
[This reply is directed to Bracer, not audioguru]
Once again, the big, bad, grouchy Audio McDuck is being very unhelpful and trying to muddy the waters here.
For the purposes of our little lesson here, you can safely ignore everything he wrote here.
(Not that he's wrong, mind you: he's raising the point that the voltage given for a LED might not be exact; his drawing showed a voltage marked by "(typ)" for "typical". However, when the
Mouser catalog page, f'rinstance, gives 3.4 volts as the "operating voltage" for this device, then I think we can take them at their word. At least, as I said,
for the purposes of this discussion.)
In other words, don't sweat it; you done good.
[to Audio McDuck:]
Where did you even get those specs? Are they for this device? If so, mind doing us the courtesy of posting a link to the source?
OK, I see it's from the
datasheet. But a couple questions for you: do you even know what "Durchlassspannung" means. I don't. (Have to look it up.)
And under the note for that parameter, they say:
Forward voltages are tested at a current pulse duration of 1 ms and a tolerance of ±0.1 V.
Not exactly normal operating conditions for a LED which we're going to illuminate with DC, yes?
OK, further research reveals that Durchlassspannung means "forward bias", "conducting state voltage" or "forward voltage" according to
this online dictionary. But the datasheet lists the smaller voltage (2.9V) as "min" and the higher as "typ". Now, this could mean any of several things:
1. That the manufacturer is so uncertain about the characteristics of this device that Vf can vary from 2.9 to 3.4 volts, which I would agree is significant,
or
2. That the "min" figure is the minimum voltage to get any usable light out of the damned thing, while "typ" is the typical operating voltage, with a much smaller variation in Vf between individuals.
Take your pick. (Maybe someone who knows better can tell us what these specs really mean ...)