Hi. I was working on a class project and some parts of the schematic required a 18VDC regulated voltage and the other partes required a 12VDC regulated voltage and I have a 120VAC to 18VAC center center tapped transformer (so I have two 9VAC outputs) (see image posted below). My question is: instead of using two separate transformers, can i connect one circuit to the 18VAC (using the two side wires) and the other circuit to 9VAC (using the center wire and a side wire)? is there any misunderstood concept that may limit that kind of configuration?

P.D.: Current consumption is not a problem because the sum of both circuits' consumption is about 800mA. Also, I understand the concept of RMS and that's the reason I know i can obtain 12VDC from a 9VAC RMS output.

Thanks in advance!

 

Yes it will work- but there is no common ground & the 12V is about 11V, not highenough to feed a regulator. Howabout using one bridge & feed two regulators- depending on expected load. Could use a buck convertor for the 12V if efficiency is important.

 

I didn't think of the two regulators solution for being a newbie and that seems to work for my project. Thanks!.

Anyway just out of curiosity and for conceptual clarity: if I add a common ground to the outputs like the image that i attached here, will it work?

 

Without a fuse in the primary,I would not try it just to see which item blew first.

 

Haha, that's all I needed to hear... thanks a lot.

 

Look closely at how the current would flow through the bridges should you insert a common ground that way.

Is there any reason you can't just rectify the 18V then have separate 18V and 12V regulators?