Ok here is the final schematic I'm going with.

Do you guys see any problems before I go ahead and order the parts to test this?

Attached Images

schematic_146.gif (51.5 KB, 142 views)

 

I would suggest replacing D4 and D5 with a bridge?, a half wave rectifier isn't much good at 50/60Hz - a bridge as two full wave rectifiers is MUCH better.

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Do you mean replace both D4 and D5 with a single bridge or a bridge bridge replacing each diode?

I ask this because I need to be able to rectify a negative voltage for the negative voltage regulator (the -5V output). If I replace D4 and D5 with a bridge I wont be able to do this.

 

You do the same as D2 and D3, that's a full wave rectifier, add two more to give the negative half as well - it's normal to use a bridge to do so.

Sorry, to be mean, but if you don't understand such a simple basic circuit perhaps you shouldn't be looking at vastly more complicated switchmode regulators?.

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If both are drawing 1 amp, the transformer is balanced so there is no problem. The worst case is 12 V at 1 amp and 5 V at 0 amp, but the transformer should handle that OK.

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I understand half-wave, full-wave, and bridge rectifiers, (the basics anyway). As far as swicthing regulators, I have to start from somewhere if I want to learn, saying "i dont know anything I give up" is not gonna help me understand them any better :wink: Pouring over the datasheets and asking questions will.

As far as what you are saying, what I am confused about is how you get the negative part of the wave in a bridge rectfier configuration to go to the negative voltage regulator. Maybe I'm just confused by the way youre wording it, do you mind putting up a quick schematic of what you are talking about?

 

Here is what Nigel is suggesting. I don't know about the transformer voltage though. I think things could get hot for the -5V regulator at full load.

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test_206.gif (4.3 KB, 103 views)

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