# How to connect photo-transistors to trigger Arduino event

I'm busy doing my finals project, and I need to have 5 photo-transistors come together on the same pin to trigger an event whenever one of these transistors drops it's voltage because an object is moving past it. I've been struggling for multiple days to fix this now, but I can't seem to get it working quite right. Do any of you see/know what I'm doing wrong? circuitry efficiency is not an issue here. I've added a circuit diagram.

• The photo-transistors are going to have to fight very hard against five 330R pull-ups in parallel. Why did you pick 330R? What voltage do you measure on the common point when bright and when dark? Where is the photo-transistor part number and datasheet link? Add all the information into your question. – Transistor Jan 8 at 21:00
• also, notice how @Transistor's nick is spelled. It'd be a shame if your final's project had a typo in one of the central components. – Marcus Müller Jan 8 at 21:01
• I fixed it already! – Transistor Jan 8 at 21:02
• I'm pretty sure that the reason you put as many 330$\Omega$ pull-ups in there is because you thought you needed one per phototransistor. You don't -- the phototransistors don't interfere with each other (much) when they're dark (although dark current is a thing), and they aid each other when they're on. You should try one pull-up resistor, and experiment a bit to see if there's a value that works reliably. – TimWescott Jan 9 at 3:45