11-01-2012 05:27 AM
Hi all!
I want to measure the voltage on the LED using the USB-6009. Scheme in attached file. If I measure voltage on R2 I see pic 1. But when I have connected USB-6009 I saw pic 2. And USB-6009 was measured this signal. Why the waveform is changing?
11-01-2012 12:16 PM
Tried using a buffer inbetween the DAQ and the measurement point? Unity-gain op-amp?
The 600x's impedance is really low, which can cause problems like what you're seeing. Use the high input impedance of an op-amp, and let the op-amp's output drive the DAQ.