virtual earth

[daiplayer]

Any body got some input on this?

Was talking to a guy that said he used this in domestic fault finding earth faults.
He ( where i would normally take an hr or so ) managed to locate and isolate a ring fault in ten mins. .

Any ideas?

 

[Knobhead]

Clues in the title . ..........

How to create a virtual ground point:
Since an operational amplifier has very high open loop gain, in negative feedback circuits the amplifier acts automatically to make the potential difference between its inputs tend to zero. Consider the simple inverting configuration below. If the non-inverting (+) input of the operational amplifier is grounded, then its inverting (-) input, although not connected to ground, will assume a similar potential, becoming a virtual ground.

So it's not this then?
View attachment 14719
Sorry to say I slept through OpAmps at collage. Not that it mattered, other than collage I've not tested one for fourty years.

 

[daiplayer]

ha ha ha !!! what a tt !! lol

 

[boberty]

Did he use the circuit tester that IDEAL make think its called a sure tester. Which will put a signal on to the circuit being tested, then you can trace it with a hand held meter. When it gets to the cause of the fault it gives a signal. Seem to remember them being £420 or pay a bit extra and you can also use as a cat scanner the gas and water use for underground services.

 

[daiplayer]

I really aint sure mate. He did the fault , then walked out ( seemed in a rush )