overload lockin amplifier

[ayham]

Hi,

I need help. I have a signal from the output of a photomultiplier. The signals breaks down when I increase the time constant of the lockIn amplifier. I can measure only with very low time constants. For example: Reference frequency was 80Hz, when I put time constant higher than 10ms the signal decreases strongly. I wonder why. Can any boday explain me this situation  and how can I solve the problem.

Thank you

[dousley]

Hi Ayham,

Could you post a schematic or a sketch of the circuit please. It would help if you could include part numbers of the ICs and hardware you are using.

Are you using dynamic signal acquisition hardware to make measurements on this circuit?

I'm not sure if I will be able to help or not, but I'm willing to take a look if you are still working on this project.

-Dousley