I'm a physics student and doing a project where I need to detect moderate intensity of light with a response as linear as possible (measuring angles using Malus law (linear polarization)). Anyways, I was using photodiodes in photoconductive mode without amplification (just a resistor in series) and it was working reasonably well, but some days ago I've got VERY noisy readings (i'm using an Arduino as ADC). I do not know the source of the noisy readings, but I suppose I should invest time into making the whole circuit more resistant to noise. Apart from low-pass-filters, I was thinking that amplifying the signal on the sensor side would help (there is a cable of about 1m length between sensor and arduino). So I was looking into basic amplifying circuits using op-amps and transimpedance amplifier circuits seemed quite straightforward to me, yet I was wrong. I'm trying to reproduce simple op-amp circuits like the one I show in a circuit below, but it just doesn't work. I'm using an LM324N op-amp.
I'm thinking about using the photodiode in photoconductive mode later (more linear as far as I know?), but first I want to get running the more simple photovoltaic-mode-circuit.
Can someone look at my connections and point out if there are some obvious flaws in it? The op-amp seemed adequate for the job. It's driving me crazy.
The circuit doesn't react to light, and instead gives me a constant output of about 779 (about 3.8V).I tried using different resistors (100 Ohms, 5kOhms, 1Mohm), and I obviously tried flipping the diode ;).
any help would be appreciated!
Edit: As has been pointed out, the circuit was wired wrongly. I did make changes to the wiring, and now I'm getting constant zero values, and very low values when illuminated with a bright, white led (20-40 on arduino scale depending on the cathode orientation, so in the order of 100mV)