I'm trying to get a phototransistor to saturate a BJT so that when a small amount of light is present, the BJT is on. At the moment, there needs to be a lot more light than I would like, so I've been looking for a way to change how much light I need. One thing I've tried is to put two of the phototransistors in series along with a resistor, and found that by pointing one away from the light, I can get a large enough voltage across one of them to saturate the BJT with a small enough amount of light. However, put the BJT B-E in parallel, and the voltage jumps down to below what is needed. I've tried using a resistor in series with the B-E junction, but it still requires the same amount of light as before. Any suggestions? Sorry about the poor schematic. I couldn't find any phototransistors, so I used BJT + arrows instead. Also, it doesn't need to be a bjt, I could get something else if it would work better.