Wiring Output with reference to Ground in a Connector

[Tebefia]

I got the attached Multisim Schematics from one of the many articles online.  However, I have a question on the schematic.

As illustrated, assuming PIN 7 is the final output signal and a User wants to measure that signal with reference to ground.   My question is how does the wiring connections between the Op-Amp and the 9-Pins Connector changes, or does the wiring connections as shown also implies that a user measuring the output signal is actually measuring it with respect to Ground?

I will appreciate any response.

[Cavarval]

Hello,

I would say it is referenced to ground. Pins 8 and 4 (from the Opamp) ultimately define what are the output limit values, so in this case the output will be Gnd =< ouptut =< Vdd. Since the lower limit is actually Gnd, the output signal will not "float". It just can't.

In order to do a measurement with an Analog Input device like a voltmeter you need to provide a positive and a negative input. In the schematic's case, I assume those would be pins 9 and 5 from the DSUB correspondingly. If so, the signal is simply ground referenced.

Please review the following articles:

KnoledgeBase 0GI7HJ03: How to Determine if an Input Signal is Ground-Referenced or Floating

Tutorials: How To Measure Voltage (see figure 1 and compare your circuit with Ground-Referenced Signal Sources in the Differential mode).

I hope you find this information useful. If you have any additional questions, let me know and I'll try to help.

[Tebefia]

Hi Cavarval:

Thanks for your response and other information.  

Best regards.