Electronics > Beginners
0V on a bench power supply = common??
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jaunty:
here's a dumb 'beginner' question ... seems there are a lot of weird little things like this that eluded me over the decades.

I'm building an amplifier circuit and the test instructions say emphatically to ensure that both this and that terminal have a solid connection to 0v on your power supply ... it's a complementary circuit requiring +/- voltages ... so i assume that would mean a floating 'ground'? someone else mentioned that i have to bridge the two sides of my power supply to get 0V - i think this would be the case for a dual rail supply that DIDN'T have a neg output (?) but my HP 6236B has a -20v output ...

sooo ... it's basically a euphemism for 'floating ground' ?

signed, slightly confused
ogden:
Some supplies have two isolated/floating channels with both, '-' and '+' terminals available for each, so you have to connect '-' of one supply to '+' of another to get bipolar supply or just double the output voltage. Your supply is bipolar supply "out of the box" where this is done already, in "common" terminal which obviously is ground.



--- Quote from: jaunty on December 06, 2018, 04:36:58 pm ---sooo ... it's basically a euphemism for 'floating ground' ?

--- End quote ---

No it's not. This ground we are talking about is as non-floating as you can get.
rstofer:
Think about 2 batteries stacked as they would be in a flashlight.  The bottom battery (+) terminal butted against the top battery (-) terminal.

Fine, the (+) of the top battery is the PS (+)  output, the negative of the bottom battery is the (-) output of the PS and the junction of the two batteries is the 0V or 'common' output of the PS.  Let's stay with 0V because a) the instructions say so and b) we have no idea whether that is 'ground'.  Or even 'which' type of ground.

cdev:
Think of it as the "middle" point of the (all voltages are relative to something) voltage range thats supplied.

You can connect it to ground if you want to but its not the same thing as ground.

You may have another terminal thats ground. (thats always connected to the case)
Brumby:
0V is just a reference point.  An ordinary single supply will have one terminal that is usually assigned this reference point - and, by convention, this is usually the "negative" terminal.

With split supplies, the usual convention is to label the mid point as 0V.

The following diagrams show the exact same circuit.  The ONLY difference is where the 0V reference point is chosen.
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