On Sat, 20 Jul 2019 22:15:27 -0400, Paul wrote:

5v and 68k ohms gives 0.00037 watts. A 1/4 watt resistor sounds OK to
me. Other online calculators recommend a full 1 watt resistor. I wonder
why.

Those LEDs will light at 1mA!

The calculator says current is 0.00007 amp, approx. 1/10 of 1mA.

Sound right to you?

That's very very good.

Perhaps too good by a factor of ten or so.

I'd double check the resistor value. A 68K would
have an orange third band, while 6.8K would have a
red third band.

https://www.petervis.com/electronics...alues/68K.html

Paul


It has 5 bands: blue, gray, black, red, violet. Here's what I used:

https://www.digikey.com/en/resources...or-code-5-band

I checked it with my multimeter too. It reads 68.0 on the 200k setting.

Two 20k in series made the LED brighter. That proves the single resistor
is more than 40k.

Hard to believe?