can anyone help me building a negative 12v from a positive 12v?

[pipoyz07]

i've build a power supply circuit that has a regulated 12v output voltage using a transformer and a voltage regulator.. what will i do to have a negative 12v output voltage from the circuit ive made? any suggestions? thanks in advance..

 

[BradtheRad]

Is your goal to make a bipolar supply connected at center ground?

How much current do you want from the negative supply?

Is your transformer (a) single winding, or (b) with center tap?

 

[pipoyz07]

yes.. my circuit requires +12v and -12v connected to it.. 200mA will be enough for my circuit..

 

[tpetar]

See this example :



:wink:

 

[IanP]

yes.. my circuit requires +12v and -12v connected to it.. 200mA will be enough for my circuit..

Everyone and their dog sell these days (3W) dc-dc mini-modules that can convert input voltage (5V, 12V, 9-18V, etc) to output (12V) @ 250mA ...
The output is isolated so it can be added to the input voltage as negative voltage - with the reference to 0V ..
See example @:
**broken link removed**

:wink:
IanP

 

[BradtheRad]

The most straightforward method is tpetar's schematic above. If your transformer has a 1A (or even 1/2 A) rating, then it should be able to provide 200mA at +12 and -12 V.

For sake of completeness... there are methods to invert +12V. Example, charge-pump, voltage doubler, switched coil buck-boost.
These will not necessarily be easy to regulate. They will require more power from the transformer in the form of greater bursts of current from your regulated +12V supply.