Question about voltages on power supplies.

[imloggedin]

If i have a 24vdc power supply that has a 24v+ 24v- and 0v output, and put a meter on 24- and 24+ would the meter show 48v? or 0v?

So on a circuit like a hamptone preamp, do you use the 0v as ground or 24- as ground?

 

[bcarso]

48. "0'" denotes the reference point.

 

[imloggedin]

so is a 9v battery -4.5 and +4.5?

 

[JohnRoberts]

[quote author="imloggedin"]so is a 9v battery -4.5 and +4.5?[/quote]

No... the battery is +9v at it's "+" terminal, relative to it's "-" terminal.

JR

 

[imloggedin]

right so is it -4.5 and +4.5 or 0 and 9+

what im trying to determine is, on some diy projects if it calls for +24v ... is it calling for -12 and +12 if you use the -12 as your ground? or +24v and 0v as ground?

 

[zebra50]

is it calling for -12 and +12 if you use the -12 as your ground? or +24v and 0v as ground?

They should be the same thing, if I understand you correctly.

Voltage is also called 'potential difference", i.e. the difference in potential relative to a reference. You have to pick the reference. Often this is 'ground', but it doesn't need to be.

Think of a 9V battery. One terminal is 9V "higher" than the other. You could call either of these terminals the reference. So we could call it 0V and 9V, or -9V and 0V,

We could add two 10K resitors in series across the battery. The mid point would be half way between the two. So now you have 0V, 4.5V and 9V, or you could call it, -9V, -4.5V and 9V. Or, if we called the mid point the reference, we could have -4.5V, 0V, 4.5V. All the same thing - it's still a 9V battery.

Hope that helps.

 

[gyraf]

24vdc power supply that has a 24v+ 24v- and 0v output

Could also be that the supply - if it really is a 24V supply - just has the neg and pos end of the 24V brought floating to the front panel - and then a chassis/0V/ground separate from this.

Many lab supplies are made like this, so that you can stack them.

Jakob E.