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Isolation for the outputs of raspberry

Hi. I want to control 4 relays from a raspberry-pi. The circuit is very simple, an NPN transistor which activates the relay. Because the relays will handle much voltage, I want to isolate from the raspberry want, and for this I thought of putting an optocoupler. I wanted to use a 4N32 but is already obsolete. What would be a correct replacement?
Thank you.