basic opamp grounding question

Yes. The only acception to the rule is if you had some form of isolation device. In the case of the isolation, you only used the ground/common of the input of the isolator device, it's output common does not come in contact with the input common how ever, the output common still needs to be connected with the circuits ground/common.

Not directly, anyway. If the amplifier is set up as a differential amplifier with unity gain. The output signal will be referenced to the power supply grounds. In this configuration, the inputs ('+' input, actually - the '-' input is along for the ride) must remain within the common mode operating range of the Op-Amp though.

___ ___ +------|___|---+----|___|-+ | R | R | | | | /-\\ | |\\| | ( )2V +----+-\\ | \\+/ Vin ___ | >--+------- +2V +-----+|___|---+----| / out R | |/| | .-. | |R | | '-' | GND (created by AACircuit v1.28.6 beta 04/19/05

Nope.

As usual for Jamie, wrong. The resistors will be the "isolation" devices (not to be confused with safety isolation).

Maybe. There has to be a return current path, of course, but your ground connection, if long, can pick up hum. A differential amplifier (amp + 4 resistors) configuration tolerates grounding induced noise (like ground loops) well, and only through a resistor does the power GND and signal GND connect. Output signal is power-GND relative, and input signal is signal-GND relative.

In noisy environments with long wires, simple signal/ground paired wiring always gets in trouble, and transformers or differential conversion is the usual solution.

That is insane,,, glad you're not in my work group.

really, kind of cracks me up.

What would be insane is *being* in your "work" group.

No, you've been there a long time.

Enough...

to know that you're not only an idiot, but a jerk.

Hardly. You advertise quite successfully.

Wrong, again. You're just about as stupid as he, though. I'm the one who gave him the (well deserved) "DimBulb" moniker, Junior.

Who haven't you mixed it up with? You let everyone know how stupid you are.

He never indicated that he couldn't, either. Your *flat* assertion that the grounds had to be the same is wrong. Perhaps you should take DimBulb's "AlwaysWrong" name.

I'm barking up the wrong tree? I pin your ears to the wall, an *I* am barking up the wrong tree? You are full of s*it, but you've been told that before.

OK, so you not only know everything, but you also know me?

That my friend is a big error on your part.

Btw, aren't you the one that is being called "Always wrong" ?

Maybe I have you mixed up with another here but it seems to fit at the moment. And also, the original poster never commented on using differential input for balanced pairs. So, go have your fun else where, you're barking up the wrong tree.

You either need to do that or configure the op-amp as a differential amplier ( in which case ensure the ground voltage of the source and the signal remains within the common-mode voltage range of the diff arrrangement ).

Graham

You're the one who's insane. You're almost as bad as AlwaysWrong.

Graham

NO

Typical Ass whip.

Figures.

You should stay out of places you don't belong.

deranged lunatic.

Typical wannabe. A perfect DimBulb clone.

What a pretender.

Jamie 5". A braggart too.

Ah, you're learning from Assilon.

Graham

Perhaps he's your mentor (it would figure), but there isn't any possibility of you learning anything. You're batting zero so far and the prognosis isn't good.

Yes, he is my mentor. Glad you noticed!

If that is your prognoses, I'm not to worried about it. I really don't give much credence to your commentary. You don't hold a candle to what I'm accustom to on a daily routine.

I understand. You're used to much worse from those who really know you. You really are stupid.