In the following picture:
I have screenshotted a picture of the front end of a phototransistor receiver circuit from Electronic Gadgets for the Evil Genius. It appears to be a phototransistor-based transimpedance amplifier. However, I am having trouble understanding the relationship between the phototransistor's collector current and the output of the amplifier, I1D.
How would I determine the relationship between the collector current and Vout in this circuit? And how would I convert this circuit to a photodiode-based amplifier? Would this improve the signal-to-noise ratio?
I've looked at a few application notes, but what am I missing?
In this circuit, C8 = 0.01 uF and C9 = 470 pF.