Negative power regulators? why?

[Souper man]

I ordered some parts from electronic goldmine, and one of the items was a semiconductor grab bag. It came with 50 brand new components, including V-regs, transistors, MOSFETs, and some logic chips. One of the v-regulators is a 7906. It supplies -6v at 1 amp. What is the point of a negative regulator? Is it like a - side of a battery? How could I use this?

 

[bananasiong]

To produce -ve supply, not ground. Some op-amp need both +ve and -ve supply, and a ground.

 

[Souper man]

Oh, what other uses could I use this for? Is this like the negative side of a battery?

 

[bananasiong]

Negative side of a single battery is consider ground. If you have 2 batteries in series, +ve side is the +ve supply, -ve side is the -ve supply and their joint is the ground.
If you want to get -ve supply from a battery, say 9 V battery. It can supply +-4.5 V whereas you can use voltage devider to make 4.5 V from 9 V, and take that point as ground reference.
audioguru has very nice diagram for the single supply of op-amp.

 

[Leftyretro]

Oh, what other uses could I use this for? Is this like the negative side of a battery?

Not exactly, think of it as two 12 volt batteries where you connect the negative terminal of #1 battery to the positive terminal of #2 battery and this connection is also brought out to become the circuit common. Now measuring from this circuit common you will read +12 from the #1 battery positive terminal and and also -12 from the #2 batteries negative terminal. This will make sense when you understand that if you measure, in this set-up, from #1 battery positive to #2 battery negative you will see 24 volts total.

Clear? In a circuit that requires both a positive and negative regulated voltages (relative to circuit common), the positive and negative regulators will perform the same function as the two batteries in the example above.

Lefty

 

[Souper man]

Oh! Thanks for help

 

[Hero999]

Look at my variable bipolar power supply project for an example of how to use poisitive and negitive regulators.
https://www.electro-tech-online.com/threads/variable-bipolar-power-supply.24291/

 

[justDIY]

the grab bag I received with my purchase was mostly a collection of old useless junk, hardly what I'd call "new components". there were a few basic leds and some photo transistors that might be handy