Need MA to voltage converter help

I have a sunlight sensor made up of 2 tiny amorphous solar cells in
parallel, that I would like to use with a 0-5 volt data logger. These cells
provide the spectral response I want.

The cells together generate a maximum of 2.25ma of current in full sunlight
that I need to convert to voltage.

I have used a OP90 op amp in the past to do the same for other sensors, but
only for microamp currents. I did the math to find the value of the
feedback resistor for this, and come up with something like .0022 ohms which
doesn't seem too workable. Either I am making a mistake in my math or maybe
it isn't possible to do this conversion using a single op amp.

Can someone give me an option for making this a>v converter for this 2.25ma
current?

Thanks
Jim

 

Not sure how you came up with that resistance value, but I'd suggest
you revisit your calculation. When I do it, I get 5V/.00225A = 2.22k
ohms, not a bad value at all. Looks like you lost 6 orders of
magnitude somewhere.

(It's always good to double-check your answers, especially in cases
like this where the result seems odd. For example, 2.25mA times .0022
ohms is 5 microvolts, not 5 volts. In other words, plug your result
back in to do the checking so you're lest apt to make the same mistake
over again.)

Cheers,
Tom

 

On Oct 9, 5:03 pm, Jim Thompson <[email protected]
Site.com> wrote:
....

Just solved the world's energy crunch, if so! ;-)

 

When I first read the OP, I misread it as nanoamps. ;-)

Cheers!
Rich