Sorry for my first really stupid answer.
I at first thought that you intended to put two secondaries in series, coming from two separate transformers. My mistake.
The connection of two diodes in a center tapped transformer is a very good practice. It saves two diodes, and provides an healthy 1.4 volts more DC output than bridge. The cost is reduced transformer efficiency: you get aprox. 90 % of the rated currenct, due mainly to the fact that there is DC current in each half winding.
You can expect safely 6,5 A from that configuration.
Good Luck!
I at first thought that you intended to put two secondaries in series, coming from two separate transformers. My mistake.
The connection of two diodes in a center tapped transformer is a very good practice. It saves two diodes, and provides an healthy 1.4 volts more DC output than bridge. The cost is reduced transformer efficiency: you get aprox. 90 % of the rated currenct, due mainly to the fact that there is DC current in each half winding.
You can expect safely 6,5 A from that configuration.
Good Luck!
But don't forget that with that configuration, you end up with a single-ended supply unless you use two transformers. I believe the OP requires a double ended "split supply" for his amplifier. Since he has 225VA transformer and he only needs 20W x2, using two transformers would be a major overkill, heck even one is more than enough. In this case, I think a bridge rectifier would be a better choice than a half-bridge.
TheMG: Off course he has two transformers. That led me to my first confusion. He has two double secondary transformers.
On the other side, if the power requirements are 2 x 60 Watts, I don't see why one toroid @ 225 VA couldn't be enough!
Dxvideo: there is some mistake in your calculus, if the amplifier is 60 Watts it can't sink more than say 80 Watts each.
Your calculated peak current of 3.25 A RMS will come half from each rail, and you will sink 1,625 A RMS from the xformer.
Make a one transformer bridge supply with the center tap to ground and test it. I'm pretty sure it will be OK.
Be careful with the polarity. It is correctly drawn on your first schematics. If the two windings are connected in series the wrong way, you'll get zero volts but nothing will be hurt. On the contrary, if you parallel two secondaries and connect them wrong the primary will burn in milliseconds!
Regards and good luck!
On the other side, if the power requirements are 2 x 60 Watts, I don't see why one toroid @ 225 VA couldn't be enough!
Dxvideo: there is some mistake in your calculus, if the amplifier is 60 Watts it can't sink more than say 80 Watts each.
Your calculated peak current of 3.25 A RMS will come half from each rail, and you will sink 1,625 A RMS from the xformer.
Make a one transformer bridge supply with the center tap to ground and test it. I'm pretty sure it will be OK.
Be careful with the polarity. It is correctly drawn on your first schematics. If the two windings are connected in series the wrong way, you'll get zero volts but nothing will be hurt. On the contrary, if you parallel two secondaries and connect them wrong the primary will burn in milliseconds!
Regards and good luck!
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