Okay I'm an idiot! Just worked out why it wasn't working. I'd stupidly connected another resistor between the optoisolator and GND and hadn't noticed I'd done it so the total resistance was meaning there wasn't enough current to turn it on! DOH!
Okay I'm an idiot! Just worked out why it wasn't working. I'd stupidly connected another resistor between the optoisolator and GND and hadn't noticed I'd done it so the total resistance was meaning there wasn't enough current to turn it on! DOH!