Andrew.Jon84
New Member
Hello.
I am trying to measure the output current from a couple of PV cells I have. However, I am not getting the expected output.
I have constructed the following circuit:
My understanding is that Vout = -IR. I then constructed the circuit as follows:
Overview:
Detail:
I measured the output current to be -4mA, so with the 1k resistor, I would expect the output voltage to be around 4V. However, it comes to only 0.8V. Moving the light closer increases the output as expected, and moving the light source away decreases the output too. However, it does not seem to reflect what I would expect. I tried using a larger resistor value, expecting the output to increase, but if anything I found the output to be _inversely_ proportional to R, which is not right at all...
If anyone has an idea as to why the circuit is behaving as it is, I would be very grateful to hear.
The op amp is a LM358N (All I have to hand right now, but I can purchase something else if need be). Datasheet here: https://pdf1.alldatasheet.com/datasheet-pdf/view/22762/STMICROELECTRONICS/LM358.html
Thanks.
I am trying to measure the output current from a couple of PV cells I have. However, I am not getting the expected output.
I have constructed the following circuit:
My understanding is that Vout = -IR. I then constructed the circuit as follows:
Overview:
Detail:
I measured the output current to be -4mA, so with the 1k resistor, I would expect the output voltage to be around 4V. However, it comes to only 0.8V. Moving the light closer increases the output as expected, and moving the light source away decreases the output too. However, it does not seem to reflect what I would expect. I tried using a larger resistor value, expecting the output to increase, but if anything I found the output to be _inversely_ proportional to R, which is not right at all...
If anyone has an idea as to why the circuit is behaving as it is, I would be very grateful to hear.
The op amp is a LM358N (All I have to hand right now, but I can purchase something else if need be). Datasheet here: https://pdf1.alldatasheet.com/datasheet-pdf/view/22762/STMICROELECTRONICS/LM358.html
Thanks.