Input signal conditioning - voltage dividing or biasing

[tmoritz]

I have a NI USB-6218 BNC DAQ unit.  Input voltage range is +/-10V.  I want to collect data from six Bently-Nevada proximity probes with a linear output range of -1 to -17V.  What is the best way to condition this signal?  Bias the common ground or set up a voltage divider?  Are there better ways?

Thanks in advance.

[santo_13]

Biasing the common ground works if the proximity sensor has a floating output. Voltage divider would be the easiest option provided the output impedance of the probes are good and your choice of resistances for the divider doesn't load the signal.

[tmoritz]

I'm going to try using some in-line attenuators.  I have some 20dB and 6dB.  Hopefully the 6dB will get me in range.  If not I go to the 20dB.  We'll see how this goes.

[santo_13]

Do note that these attenuators load the signal from the sensor, ensure that this loading is not significant or you will get inaccurate measurements.

[Henrik_Volkers]

insert a 9V batterie?

OK, while this would work, the voltage stability of such a source migth not be the best 😉  adding a 7-8V  low drop voltage stabilizer would do the job.

So one stable voltage source and a OP amp per channel to add the voltage ( and another for an input buffer) 

[tmoritz]

Mr. Volkers - Thank you for your response.  I am now planning on building a signal conditioning box using op amps to amplify (or attenuate) and bias these vibration signals.