We've been tasked to find a creative use for a phototransistor at uni.
I was wondering if this would work, and if there's any flaws to my workings:
The NPN phototransistor is used as an emitter circuit, which means that in its idle state without light the output is high going in to the LM339 +ve. If the source voltage is +5v, the voltage drop across the resistor is 4.3v, because there's a 0.7v drop across the phototransistor because its turned on.
So at idle state, LM339 +ve is 0.7v, -ve is 5v, and LM339 output is high
I was wondering if this would work, and if there's any flaws to my workings:
The NPN phototransistor is used as an emitter circuit, which means that in its idle state without light the output is high going in to the LM339 +ve. If the source voltage is +5v, the voltage drop across the resistor is 4.3v, because there's a 0.7v drop across the phototransistor because its turned on.
So at idle state, LM339 +ve is 0.7v, -ve is 5v, and LM339 output is high