I thought I understood transistors but now I'm confused again.
I have a basic opamp circuit to amplify the input of a electret microphone. The output of the opamp will vary within 1-4V. Now I want to connect this output to a load (laser) and this modulate the light intensity via the mic.
The driver of the laser is not a constant current one, and output does change if input changes, thus modulation is possible.
The thing is that I cannot connect the laser directly to the output of the opamp circuit because the current flow will be to high (+-300mA), so this means I need to use a transistor right?
So I thought I can just connect this output to the base pin of the transistor(2n2222), the load from +5V to collector, and emitter to ground. The base input then controls the current over the proportionality.
So basicly a input of 1-4V on base must control the collector current also from 1-4V but allowing a larger current to flow.
I read that the base-collector current must not be the same and this shuts down the transistor. I tried a basic circuit and obviously it didn't work.