Help understanding the circuit.

I'm working on a pcb layout combining multiple circuits. I am generally good at making what I need work, that being said combining circuits isn't my issue. I will include a screenshot showing the original circuit I'm intergrating. it's used to program esp32 wrover. Looking at the schematic it uses 10k resistor on a 3.3v line to a led that is connected to the tx line for ground. I ran the numbers and a 10k resistor dropping 1v is .1ma, would that even light a led enough to be visable? Theres a total of 5 leds like this, but the answer will explain them all. in the picture included its the bottom right corner. To be clear I'm using parts of this circuit but not it all, I just need the programming portion so like 75% but that 75% is like 33% of the project and the rest is 100% original.

Why not try it? ::slight_smile:
Don't you even have an LED and resistor?

State-of-the-art LEDs are extremely bright with tremendous efficiency.
If it is used as a pilot-lamp or indicator, 0.1mA gives off enough brightness.
It may even be bright enough to be visible even at less than 0.01mA...

mwdsonny:
I ran the numbers and a 10k resistor dropping 1v is .1ma, would that even light a led enough to be visable?

Yes.
Those tiny LEDs could take an absolute max current of 10-20mA, but that doesn't mean you must drive them with that.
I had to drop the current of a computer case power LED with a 47k resistor to not be annoyingly bright anymore.
Leo..

Wawa:
I had to drop the current of a computer case power LED with a 47k resistor to not be annoyingly bright anymore.

The intensely shining blue 0805LED at my display’s power indicator was shortens my life…
I killed that promptly.
Terrifyingly he was driven at 100Ω by 3.3V VCC. :astonished:

Your avatar really makes volunteers jump at the chance to help you.

Wawa:
Yes.
Those tiny LEDs could take an absolute max current of 10-20mA, but that doesn't mean you must drive them with that.
I had to drop the current of a computer case power LED with a 47k resistor to not be annoyingly bright anymore.
Leo..

If only consumer electronics designers would get the same message and realize that indicator lights DON'T NEED TO BE BRIGHT. I could read a damn book by the light of my computer's disc drive's power LED.

Typical led resistors are 220 ohms.
Was there other specific questions ?

raschemmel:
Typical led resistors are 220 ohms.
Was there other specific questions ?

Sure, if you want to blind yourself and everyone else in the room. If there's any chance of your project being used in a dark room please be merciful to your eyes.

NO MERCY.

"Let there be light..."

10k resistors are way past merciful.
You might as well be blind.

@OP,
At the end of the day it's your call. Usually , it is
assumed that a newbie asking about led resistor
values is talking about a circuit that will be used
in daylight or standard room lighting, not in a dark
room. This is really a trivial issue since you are
already at the maximum resistance level. You
can increase intensity by reducing it 1k at a time
to suit your needs. For the record, I doubt you'll
find any cases in the medical books of people being
blinded by 5mm leds. You are already aware that
the sky's the limit on available led power ratings
so nobody is talking about high power leds in this
discussion, like mounted on police helicopter or
commercial aircraft landing lights.

Jiggy-Ninja:
I could read a damn book by the light of my computer's disc drive's power LED.

Put it next to the bed. :grinning:

Since you are at the layout stage simply add any resistor value you like. Then when you get the boards use test probes and resistor(s) to determine how bright you want the LEDs to be. Then put that value in.

Else you could purchase, make a resistor substitution box.

JohnRob:
Else you could purchase, make a resistor substitution box.


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