led's and resistors

[Mark Hammer]

Hmm, I use clear bright leds in my stompboxes with a 10k resistor...

That's why I suggest values as high as 18k in my proposed tester box.  I think I have one pedal with a 3000mcd clear bright in it that uses an 18k, and its bright enough for me.

[Gurner]

Hmm, I use clear bright leds in my stompboxes with a 10k resistor...

Good....if that gave you sufficient brightness, but the resistance figure means nothing in isolation  ...for example - what colour of LED, what power supply voltage, what type of LED (mcd output etc) and most importantly how does everyone quantify what your 'sufficiently' bright does for them & for their application etc.

[DavenPaget]

I always use 20ma as a safe rating . 25ma is too much .

[Gurner]

I always use 20ma as a safe rating . 25ma is too much .

That might be your interpretation of safe, but I'd rather roll with the people who make actually the part.

The absolute maximum rating is the level at which the part has been thoroughly tested by the manafacturer and a safe figure derived at....so if they are saying 30mA is fine in their datasheet, then 25mA is totally fine (in fact, it's highly likely you could run the LED at say 35mA ...because they typically build in a bit of slack)

If we aren't gonna believe the manafacturer's datasheet (& remember it's in the maker's interest to make sure their quoted absolute maximum figure is well within safe itself ....else there's gonna be a lot of 3rd party manafacturer's hitting them with court cases!), then we may as well all give up & take up upholstery!