Optocoupler

An optocoupler can be used to control a circuit that's completely isolated from your microcontroller. In this case, imagine that the LED and battery pack are a hacked toy which you're turning on and off with Arduino.

Use an optocoupler such as the 4N35. Connect the optocoupler's pin 2 through a 220Ω resistor with Arduino's pin 11, and pin 2 with Arduino's ground. Then connect your external circuit to pins 5 (collector) and pin 6 (emitter). You can also apply voltage to pin 4 (base) of the optocoupler to raise the gain (just like with a normal transistor).

By omer
Created on April 2, 2009, 13:55

Category: Digital

Difficulty: kids

License:

Tags: optocoupler, transistor

Images

Files

Fritzing Files

optocoupler_Optocoupler.fz

Links

Wikipedia: Opto-isolator

Comments

thesavager # Sept. 18, 2009, 7:57 p.m.
Hi Omer, I saw a few errors in your documentation, so I've corrected it for the others. Use an optocoupler such as the 4N35. Connect the optocoupler's pin 1 through a 220Ω resistor with Arduino's pin 11, and pin 2 with Arduino's ground. Then connect your external circuit to pins 5 (collector) and pin 4 (emitter). You can also apply voltage to pin 6 (base) of the optocoupler to raise the gain (just like with a normal transistor). Gr. Pascal
uaneme # Aug. 15, 2012, 6:15 p.m.
How do I get a KB-817 optocoupler in fritzing? http://www.ecnmag.com/articles/2010/12/design-guidelines-transistor-output-optocouplers If you use the pull-up design instead of pull-down then the circuit would not be inverted. What would be an ideal resistor for Digital mode operation (compatible for 3v3 and 5V) at the highest possible switching speed?

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