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Topic: Starter Kit Project #15 optocoupler (Read 145 times) previous topic - next topic

StewieStew

I'm trying to gain a better understanding of optocouplers. In my project, I am attempting to use an optocoupler to activate a pushbutton that will power an LED (the LED and pushbutton simulate a separate circuit). Once the Arduino powers on, the LED lights up successfully for three seconds before powering off, and never turning on again regardless of the delay values I input into the program. If anyone can explain what exactly is happening I would greatly appreciate it.


pwillard

You only activate the Optocoupler LED for 15ms and you expect to see it?   Maybe you need to turn on that LED a bit longer... like 2 seconds...

Note to all: USE DRAWINGS not photos of your "air wires".  The pictures are almost useless as a reader will run out of patience trying to figure out what your intentions are.

groundFungus

I don't see a current limit resistor for the LED.

Paul__B

Once the Arduino powers on, the LED lights up successfully for three seconds before powering off, and never turning on again regardless of the delay values I input into the program.

Hmmm.  You don't suppose that is because you have it connected to pin 1 of the Arduino instead of pin 2?  :smiley-eek:  This is the Tx pin, activated while Optiboot waits to see if you want to program it, then shuts off until you activate the serial interface.  :smiley-roll:

I don't see a current limit resistor for the LED.
I do.  :smiley-lol:

TomGeorge

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Currently it is hard to see the orientation of the Opto and LED.

Just as you have a current limit resistor on the input to the opto, you need a current limit resistor in series with the LED.

As has been pointed out the delay(15), is a delay of 15ms, try delay(1000), it will turn the LED on for 1000ms or 1Second.

Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

StewieStew

Yup this fixed the issue, *Slaps face

[/quote]

Hmmm.  You don't suppose that is because you have it connected to pin 1 of the Arduino instead of pin 2?  :smiley-eek:  This is the Tx pin, activated while Optiboot waits to see if you want to program it, then shuts off until you activate the serial interface.  :smiley-roll:
I do.  :smiley-lol:


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