I'm working on a primarily optical project, but I need to get a simple circuit working. I'm working with an npn 3-lead phototransistor (datasheet).
I was trying to get the current from the phototransistor to control a cheep set of headphones (64 ohms). I've tried using a configuration like Figure 26, but simply cannot get the transistor out of cutoff.
I'm having difficulties troubleshooting the circuit myself, as I do not understand how a 3-lead (rather than a two-lead) phototransistor works and have not been able to find resources on the topic. Resources, designs, or explanations would be incredibly helpful.