connect a photodiode

[Andrea]

Hi,
I have a BNC 2120 module and a 6111 acquisition card. I want to
acquire an amplifier photodiode. How can i do this? I have tried to
connect directly the photodiode to the 2120 module, but i can't see
any signal, i think that there is a impedence coupling problem. So i
have make an impedence adaptor, but is this the only way to resolve
this problem? Normally we can see the photodiode with a normal
oscilloscope that have an input impedence of 1 Mohmm. Is there a
special configuration of the BNC module or the card, to acquire
directly the amplified photodiode?

Thank you for the attention

Andrea

[Tiptop]

Hey Andrea,


Before you worry too much about impedance problems (which are explained here) first make sure that you can read in dc voltages correctly.

Other things to check:

1.) Is the referencing set in MAX equal to the referencing set on the board?
2.) Is the board configured to use the BNC-2120 in MAX?
3.) Will low impedance sources work?

If all of these point towards the source impedance of the photodiode being the problem, then the only real solution is a buffer. Here is a link to information about using a unity gain buffer.

Let us know i
f you have any further questions!

Justin T.
National Instruments