Current to voltage converter

[kam123]

Hi
I want to build a current to voltage converter with op amp, which measure the intensity of sunlight during the day. I'm using a small solar cell taken out from a solar calculator. I've done some research on the web about solar cell and found that its current vary linearly with light intensity. I have LM324 op amp available, since it can be operated with single power supply (eliminating the -V problem)

Can any body suggest a schematic or explain to me how to do it.

thanx

 

[FvM]

 

[kam123]

Thanx

But what about the value of the resistor and capacitor?

the solar cell I'm using generate about 200 micro ampere during bright sunlight.

Also can u explain to me the use of the capacitor

 

[IanP]

This is so called trasnimpedance amplifier and if you intend to supply it of single voltage you should consider rail-to-rail (input and output) opamp ..
The LM324 may be not suitable for this application but if you have it - give it a try ..

Details on transimpedance amplifiers are here:
http://www.ecircuitcenter.com/Circuits/opitov/opitov.htm

Rgds,
IanP

 

[FvM]

Hello,

R would be intended Vo/Ie, e. g. 5V / 200 uA = 25 kohm, select 24 kohm.
C is necesarry to achieve stability with photodiode capacitance and isn't very critical could choose e.g. 1 up to 100 nF. Higher values can provide a low pass filter.

Regards,
Frank

P.S.: LM324 would be well fitted, cause input range includes negative supply, also output voltage goes near to V- and could be effectively zero with an additionally load resistor. Would be an issue, if you intend to measure down to zero with unusual high dynamic.