Problems aquiring a voltage from charge amplifier Kistler

[jb29n]

Hi,

I want to aquire charges (in pFarads) from a piezoelectric material, then I connected a Kistler charge amplifier to my sample, as an output of the charge amplifier I will have normally a voltage directly proportionnal to the charges.

The charge amplifier is connected through BNC cable to a BNC 2110 and then to a NI PCI 6115 card.

I acquire the voltage signal with MAX (1sample) and the result is... catastrophic, quite nothing (mV around 0V).

BUT when I connect a voltmeter to the kistler charge amplifier (with the same parameters, TC and else) I have a perfec answer: around 8V and this voltage follow the pressure I apply to my sample!!

Anyone has an idea about the mistake I have while acquiring through the PCI card???

Many thanks if yes!!

JB

[crossrulz]

How is your channel setup?  My guess is you have it as a Differential when it should be Referenced Single Ended (RSE).  Also make sure your grounds are all connected.

[jb29n]

Thanks, I'll check the Differencial, the only ground is the Ground Source of the BNC 2110 and it's OK.