Optocoupler PC 817

will7o20602

New Member
Hi All ,

i'm totally new with optocoupler , so i need to use it nowadays with a microcontroller project to get a signal from the microcontroller and then control 12V contactor of a relay

Anyone can help me?
 

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i tried but it still not working. When i check there is 3.9 V on the 470 ohm resistor..

hi,
That very old type photo-coupler will not drive a relay directly, you require a drive transistor after the coupler.

EDIT:
Like this.
 

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Last edited:
additionally to ericgibb's I suggest to use a 6N139 optocoupler for direct connection to an MCU I/O pin.

The 6N139 transmitter requires 1.5mA only, thus keeping current requirements for I/O ports to a minimum.

Boncuk
 
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