Dual full rectifier supplies - Page 2 - Electronic Circuits Projects Diagrams Free

Roff · 22nd January 2005, 04:05 PM

Quote:

Originally Posted by TheOne

I was thinking in terms of a light or no load and the danger of max input voltage to the regulator which is -40V. The -ve section will still work as a 1/2 wave voltage doubler where the top will be normal full wave rectification. The dissipation in the -ve regulator will be much higher than the +ve one.

Ron, you have to analyze it over more than 1 cycle to see that the voltages from the caps will add.

I was looking at the transformer as 12.6VAC across the terminals. Now I see it says "CT". So what is the voltage across the bridge? Isn't a center-tapped transformer spec'ed at end-to-end-voltage, i.e., wouldn't it be 6.3VAC from CT to each end? Even if the AC voltage is twice what I simmed, the magnitude of the negative output voltage is less than the positive output.

TheOne · 22nd January 2005, 07:19 PM

Ron, I think the difference is that I assumed that he is using a center tapped transformer and just neglected to show the center tap connected to GND. If it is not a center tapped arrangement then the -ve voltage will be lower. I have not drawn in the C.T and transformer, but set up the incoming AC to act in such a way. Here I have taken the effort to use a transformer and simulated both conditions.

The one is a 12.6V + 12.6V and the last a 12.6V only.

**Nigel Goodwin** · 22nd January 2005, 07:27 PM

Quote:

Originally Posted by TheOne

Ron, I think the difference is that I assumed that he is using a center tapped transformer and just neglected to show the center tap connected to GND. If it is not a center tapped arrangement then the -ve voltage will be lower. I have not drawn in the C.T and transformer, but set up the incoming AC to act in such a way.

NO! - the centre tap must not be connected to ground, it's a bridge retifier circuit, the centre tap isn't used - giving the full 12.6V from both windings to feed a single rail. His original diagram was drawn quite correctly.

Sebi · 22nd January 2005, 07:55 PM

This cct also work with one bridge.

Sebi · 22nd January 2005, 07:59 PM

oops! TheOne, Your upper cct make a total shortcut for transformer...

**Nigel Goodwin** · 22nd January 2005, 08:00 PM

Quote:

Originally Posted by Sebi

This cct also work with one bridge.

Yes, a standard fullwave rectifier, using a centre tapped transformer (or in your diagram two transformers), generating split supplies.

But this wasn't what he wanted to do.

TheOne · 22nd January 2005, 08:17 PM

But his original circuit won't work with one winding at 12.6V (unless he removes the GND from the bridge and connects it as a centertap 12.6V+12.6V) as the -ve voltage is then too low to feed the -ve 12V regulator as Ron also found in his first simulation. Will only work with a doubler setup. One of the first posts say something about a center tap transformer on the diagram. :?

Sebi, yes! (fixed), like I said the -ve side will be 1/2 wave doubler and the +ve side standard full wave.

Quote:

I was thinking in terms of a light or no load and the danger of max input voltage to the regulator which is -40V. The -ve section will still work as a 1/2 wave voltage doubler where the top will be normal full wave rectification.

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22nd January 2005, 07:59 PM	(permalink)
Sebi	oops! TheOne, Your upper cct make a total shortcut for transformer...