How best to avoid ringing between preamp and counter input on AT-MIO-16?

[sonnymoon]

I am trying to count pulses from a pre-amp using counter chips on the AT-MIO-16 but I am getting lots of ringing (150 MHz when I should get 1-10 Hz) even with a 50 Ohm terminator cap. Any suggestions?

[Ben]

Match the impeadence of

the pre-amp out,
cable,
AT-MIO-16 input.

Prefect matching gives zero ringing.

Ben

[Filipe A.]

Hello;

This is looking like an impedance mismatch in between the DAQ device and the source of pulses device. When the impedance is not matching, a percentage of the waveform reflects back to the source, creating the ringging.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments