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LED currents?

E

Eeyore

Jan 1, 1970
0
Jan said:
Since WHEN did green LEDs have a Vf of 3V @ a couple of mA ? It'll be
more like 1.6V.

So I = 3.4/680 = 5mA

LEDs have moved on over the years, these drop 3V.
Go to the shop and buy some recent high brightness ones :)[/QUOTE]

OK, that's not a 'standard' LED.

Graham
 
E

Eeyore

Jan 1, 1970
0
RHRRC said:
Nichia gives 2.8V typical at 1mA (Ta=25C) for a dominant 544nm at this
current (NSPG xxxx devices)
The lighter green devices (NSPE xxxx) are given as 3.0V typical at 1
mA for a dominant 505nm

Different to the LEDs I'm used to.

Graham
 
S

Spehro Pefhany

Jan 1, 1970
0
Different to the LEDs I'm used to.

Graham


3.0 Vf at about 7.5mA for the ultra-bright greens I have around..


Best regards,
Spehro Pefhany
 
J

Joerg

Jan 1, 1970
0
Henry said:
For the price you can get just two ;-)

But then you also have to schlepp around both of them.

Mine have indeed 3 cells with one switch and one white LED. Nothing
more! A very pleasant stable case. All metall. 3 Euro.

They probably use the internal resistance of coin cells as the limiter.
This is not your price. They just want to clear off the store.

Probably. I guess the Christmas sales weren't quite as expected everywhere.
 
J

Joerg

Jan 1, 1970
0
Robert said:
There's your "constant-current" source.

Nope, the button clicks through five states and only the last one turns
that bulb on.
 
R

Rich Grise

Jan 1, 1970
0
I was just soldering a LED in a PIC circuit so I can test some software
I am writing.
Now I want low brightness, so I derated, 680 Ohm in series, 5V, 3 V LED
drop, green LED.
I bought some of the brightest greens ones some time ago... Switched it
on, had to close my eyes: 2.9 mA WAY to bright!!!

So what do you guys use for LED current these days for a normal non
blinding clear transparent green LED (say on indicator)? < 1mA?

Use a pot, and turn the knob until it's the "right" brightness. Then
measure the pot, and use the closest standard value.

Have Fun!
Rich
 
D

Don Klipstein

Jan 1, 1970
0
What green LED has a 3V drop? ISTR that they drop around 1.8-2.2V.

*WHITE* and blue LEDs drop around 3.5V.

There are InGaN green LEDs. Voltage drop is usually about the same as
for white and blue ones. These green ones have peak wavelength usually
around 520-525 nm and dominant wavelength (a color specification) around
525-530 nm.

- Don Klipstein ([email protected])
 
R

Rene Tschaggelar

Jan 1, 1970
0
Jan said:
I was just soldering a LED in a PIC circuit so I can test
some software I am writing.
Now I want low brightness, so I derated, 680 Ohm in series, 5V,
3 V LED drop, green LED.
I bought some of the brightest greens ones some time ago...
Switched it on, had to close my eyes: 2.9 mA WAY to bright!!!

So what do you guys use for LED current these days for a normal
non blinding clear transparent green LED (say on indicator)? < 1mA?

Jan,
I'm using the high brightness 1206 LEDs with
7.5k in Series at 5V, which amounts to in the
range of 400uA.

Rene
 
J

Jan Panteltje

Jan 1, 1970
0
Jan,
I'm using the high brightness 1206 LEDs with
7.5k in Series at 5V, which amounts to in the
range of 400uA.

Rene

Thank you, appreciated :)
 
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