Are all 3mm LEDs created equal?

I'd like to one use these -

https://www.railwayscenics.com/single-cr2032-cell-button-battery-holder-with-switch-p-3593.html

to power LEDs in one of my remote structures to avoid the need for yards of electric string., so with a spare CR2032 battery tried to light a white 3mm LED. No joy. I tried a 3mm red LED, bingo! It worked. Now both work equally well on my 12V LED power source, with either one or two in-line 680K resistors [Bright and duller].

Why?

Are the white ones like a flourescent tube, i.e. need a 'kick' to start shining?

Unilluminated Chubber

White Led's need about 3.5volts while Red led's need only 1.7 to 2.3 volts.There's some information on the various voltages needed here.
https://kithub.cc/2015/11/how-many-volts-are-needed-to-power-an-led-2/

Tony.

Oh! Thanks for your reply, Tony, does this mean that I can't use one of these holders for white lights, then? There is a double CR2032 holder available, not much bigger, but that would give about 6V so I'd be into the resistor scenario again, wouldn't I?

Douglas

[user=312]Chubber[/user] wrote:

Oh! Thanks for your reply, Tony, does this mean that I can't use one of these holders for white lights, then? There is a double CR2032 holder available, not much bigger, but that would give about 6V so I'd be into the resistor scenario again, wouldn't I?

Douglas

I don't know Douglas as I normally use a dc power supply to power leds with a resistor between each led & power  supply.  If you used two 3 volt batteries, that would give you 6 volts which would need a small resistor.
Tony.

So using a 6v source & the nominal current of 20mA for white LEDs, you need a 135 ohm resistor 1/4 watt.

Thank you, Ron, guess I shall have to source some. I presume  to get a more dull glow(bedroom) I could put two in series.

D

If you're lighting your bedroom with a 6v LED, I think you'll also need to keep a torch handy Doug ……………………….. :cheers

Thanks for the link to that battery holder Doug. Useful piece of kit, and a reasonable price, too.
Best regards,
Shaun.

[user=6]Petermac[/user] wrote:

If you're lighting your bedroom with a 6v LED, I think you'll also need to keep a torch handy Doug ……………………….. :cheers

…I am not currently at home to Mr Silly…

D

[user=312]Chubber[/user] wrote:

[user=6]Petermac[/user] wrote:

If you're lighting your bedroom with a 6v LED, I think you'll also need to keep a torch handy Doug ……………………….. :cheers

…I am not currently at home to Mr Silly…

D