Galvanic Isolation Help

Thread Starter


Joined Apr 28, 2009

I submitted a thread not too long ago regarding patient isolation:

"I am currently working on a project to measure complex impedance. This is done by introducing a current (~1mA) @ various frequencies (1k to 1M Hz). I would like to float all components in contact with the load. To do this, I would like to use an opto-isolator do to their availability and cheapness. I am having problems locating one for my specific use. Any suggestions?"

I have not really received helpful responses or solutions to the problem. I just realized that the lab I am working in has an isolation transformer power station. Therefore, if I were to plug the output and input of the circuit into this power jack, does it provide isolation to the load? I will power the rest of the equipment using batteries. The circuit would be as follows:

Power>Isolation Transformer>Function Generator>Current Limiter>Electrode In>Patient>Electrode Out>Instrumentation Amp>Oscilloscope>Isolation Transformer>Power

Essentially all items in bold would be referenced to a floating ground as compared to the input Function Generator and output Oscilloscope.

Is this valid? If not please explain. Thank you!


Joined May 16, 2005
The power isolation transformer provides isolation from the mains. It cannot isolate your bold-print items from your standard-print items.