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Using an optocoupler ?

Hi
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
Aki

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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.

Like this

uP-OPTOISO.jpg
jchumpfree13 years ago

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.

akinich (author) 3 years ago

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 ?

20mA per pin

Look up voltagfe divider.