Today I was working with an optical encoder (Agilent QEDS) that's found in one of the old printers. The encoder has two channels which gives two signals with a phase shift of 90 degrees. I was trying to read the signal in LabVIEW using PCI 6035E Data Acquisition Card (DAQ). But the moment I connect the pin of labview, the signal was getting lost. Then after doing some research I found out that I need to isolate/condition the signal since the DAQ needs more current than the encoder can provide.
So there was a need for buffer. I first used 74367 IC but it didn't work out. The next thing I came across was to use a voltage follower circuit using an op amp. Picked up a LM324 IC and quickly hooked up the voltage follower and BOOM ... the signal was ready to be used in LabVIEW.
You can look at this link for detailed information: http://en.wikipedia.org/wiki/Operational_amplifier_applications
Conclusion: If there is any sensor which generates a signal with a very small current and you need to maintain the same voltage, use an op amp voltage follower to condition the signal to get a higher output current.
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Note: Once my project is complete I will surely post the complete details.
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