+12V? -12V?

[[email protected]]

Really basic question. What is usually meant by -12VDC?

I thought that if you have a 12V battery, one end is +12V, and the
other end is GROUND (-).

How can you be "below" ground?

 

[Ralph Mowery]

Really basic question. What is usually meant by -12VDC?

I thought that if you have a 12V battery, one end is +12V, and the
other end is GROUND (-).

How can you be "below" ground?

Think of it as two 12 volt batteries in series. From the junction of the
batteries (use this as the ground refferance) you will get +12 volts on one
battery and -12 volts from the other battery. Some devices using
intergrated circuits are set up this way. Many of the eairly computer
supplies had a -12 volt supply in refferance to the ground. The rs232 port
(serial port) worked this way.

 

[[email protected]]

Think of it as two 12 volt batteries in series. From the junction of the
batteries (use this as the ground refferance) you will get +12 volts on one
battery and -12 volts from the other battery. Some devices using
intergrated circuits are set up this way. Many of the eairly computer
supplies had a -12 volt supply in refferance to the ground. The rs232 port
(serial port) worked this way.

Oh! Got it now, thanks. I'd (erroneously) thought that -12V meant the
negative terminal of a 12V battery.

 

[Pooh Bear]

Really basic question. What is usually meant by -12VDC?

I thought that if you have a 12V battery, one end is +12V, and the
other end is GROUND (-).

How can you be "below" ground?

If the + terminal is attached to ground the - terminal is then at
-12V.

Graham

 

[Mochuelo]

Oh! Got it now, thanks. I'd (erroneously) thought that -12V meant the
negative terminal of a 12V battery.

A voltage never refers to "one point," unless there is a clear
reference point assumed. It always refers to something of one point
with respect to another, explicit or implicit, reference point.

voltage = potential difference

Best,

 

[Jasen Betts]

Really basic question. What is usually meant by -12VDC?

I thought that if you have a 12V battery, one end is +12V, and the
other end is GROUND (-).

How can you be "below" ground?

conect the + to ground and not the -, then the - will be below ground.

Bye.
Jasen

 

[colin]

Really basic question. What is usually meant by -12VDC?

I thought that if you have a 12V battery, one end is +12V, and the
other end is GROUND (-).

How can you be "below" ground?

That is the usual case that you are familiar with from cars etc however you
are not limited to conecting the (-) terminal to ground/earth/chasis etc.
ground is a just a usefull reference.

If you have 2 bateries in series and conect ground to the middle conection
then you have both +12 and -12 available.

Colin =^.^=