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Using an optocoupler ? Answered

i got a few opocouplers , MOC3023
I read the data sheet and it says that the input voltage for the control side is about 1.2v
I want to use it with an arduino uno , any idea how to reduce the voltage from 5v to 1.2v?
here is the link for the data sheet http://www.fairchildsemi.com/ds/MO/MOC3023M.pdf

Thank you in advance



Just use a dropper resistor, you're driving a little LED inside the package. Reckon on say 20-40mA into that, and something like 180 Ohms should work.

The input is an IR led diode. According to the spec sheet, the max current for the emitter (input) is 60 milliamps. If the arduino outputs 5 volts, subtract 1.2 (input LED voltage drop) from 5 volts. That gives you 3.8 volts divided by .06 (milliamps) = 63 ohms (max). A 100 ohm resister in series with the input would work nicely (38 milliamps) for 5 volts.

.The ABSOLUTE maximum output current for an Arduino pin is 40ma, the maximum recommended current is 20mA, the diode will run happily on that.

How about driving a normal 3mm green led in series with the optocoupler?

If i were to do that how many pins can i run before exceeding the max current limit for atmega ?

Look up voltagfe divider.