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Topic: LEDs without the use of current limiting resistors (Read 5 times) previous topic - next topic

Hippynerd

I like where your heads at. When in doubt, measure it.

I dont have a scope, I do have a couple cheapo digital multimeters.
Not only is it multiplexed, but its charliplexed. 192 LEDs on 16 arduino pins.

I have a spare arduino, is there a way I could make a scope out of an arduino?

CrossRoads

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

dhenry

Quote
but I have no idea how to test the theory.


You don't need to: the datasheet lays it out clearly for you.

The typical diodes have a log-linear v-i curve, and the typical leds have a logn-linear v-i curve at low current levels and a linear curve at high current levels.

The resistor really is there to provide some negative current feedback to prevent a thermal runaway on the diode.

AWOL

I take this as an implicit "I'm happy to field all future "my Arduino and/or LED array is knackered because I don't understand current limiting or datasheets because I'm an artist/hobbyist" type questions" from now on, dhenry.

Well volunteered.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

Hippynerd

#19
Jan 08, 2013, 05:16 pm Last Edit: Jan 08, 2013, 05:18 pm by Hippynerd Reason: 1
You use a lot of words that dont make a lot of sense, are you intentionally being confusing?

It sounds like you thing that someone here hasnt read a datasheet or heard of a current limiting resistor being used with an LED, but im pretty sure everyone here knows about that stuff, so this just sounds like an insult with no merit, why even post it?

Thanks for the link, im going to read up on simplot today.

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