retrolefty:
Yes, that is a proper interface from opto to relay switching transistor. I would not bother with having two visual leds performing the same function, I would eliminate the opto input led indicator and adjust it's series resistor to compensate for it's elimination.Lefty
Wow, I just noticed the LEDs.. You're right. I will have to change my design for the relay LED. I wanted the LED to light when the relay has power (Not switched on). The LED on the opto would light when the relay switched on. It's not really a necessity to have either LED, but I like seeing the lights. Besides, I have hundreds of 1206 LEDs in a variety of colors..
Thanks Retro and Papa. Just to let you know Papa, I knew how transistors worked, but the symbols stumped me for some reason. Last night (late), it finally sunk in. So, +1 to ya both.
AlxDroidDev:
Instead of using 8 Arduino pins to drive your board, why no use one a single 74HC595 between the arduino and the optocouplers?This way you'll use only 3 arduino pins, instead of 8, and the complexity added to your design will be minimal (and a 595 is pretty cheap).
Good idea, have quite a few of those in SMD that I have been wanting to use.