Voltage Potential vs. Rating

[nathon]

I have an odd question. In my (limited) understanding of voltage and current, it seems it's really the potential (difference) between the ground and VCC states that make a circuit operate.

This being said, are ratings also simply a function of that difference? I give two examples below with my assumptions. You can tell me if I'm wrong.

1: Ground is 50V, VCC is identical to GND (50V). I assume the circuit will do nothing. Any components rated below 50V won't care since there is no difference between GND and VCC.

2: Ground is 50V and VCC is 5V higher (55V) on a circuit designed to operate at 5V. I assume it will operate as intended. Components rated for 5V will function normally.

Can anyone tell me if I'm mistaken or not and why? Of course I'm ignoring Earth ground references in these examples. These would of course have to be floating.

Thanks for satisfying my curiosity. I don't have any electronics education and am trying to determine if I understand things correctly. This is one question I've been asking myself for a while.

[retrolefty]

  As an example certainly say 3 5vdc  power supplies can have their outputs wired in series to make available +5, +10, and +15 volts relative to negative terminal of the 'bottom' supply, as long as the supplies have isolated outputs relative to their AC input terminals.

 Your use of 'ground' term is taking on a more important role then it is in reality. In the above series supply example one could use the positive terminal of the 'bottom' supply be called and used as 'ground' and therefore have available -5vdc, +5vdc, and +10vdc. What you use and call 'ground' should rather be called 'circuit common' or just 'common' to make it clear that you, the circuit designer, is the one that determines what circuit point is to be common and all other voltages are relative to that circuit common point.

Ground, earth, circuit common terms can be confusing to newcomers (and some old-timers) and usually requires more 'system context' to best describe what is trying to be confided in the circuit schematic.

[Neilm]

You have that understanding correct. It is the potential difference across a component that causes it to work. It does not matter if the reference (0V) voltage is connected to earth, 50V or 50kV. It will also work if the 5V is connected to earth, with the 0V being at -5V. (indeed, that is the way some inverter circuits work).

[nathon]

Thanks guys! I'm picking this stuff up as I teach myself. That topic was one that I was sure must be true, but I wanted to put it to the smart people here to make sure.

I'm kind of nutty in that I have a need to know every microscopic detail of something before I'm satisfied. Thanks for helping me get a little closer. :-)