12 Volt Regulated Supply

I was looking at a 12 volt regulated power supply at *** Smith
Electronics cat. number M9935 @ www.dse.com.au for a regen radio I'm
planning on building (http://www.schmarder.com/radios/tube/
1-12af6.htm) but the AU$24 is a bit too high for my liking. I was
thinking of using a center tapped transformer, 6.3-0-6.3V @ 500mA, in
series with a 1.3 watt zener diode, I need help with obtaining 12.6
volts from a center tapped transformer, I never had to do it before.
I thought that the two positive primary leads were connected, I don't
want to blow the transformer if this isn't the case.

Any help appreciated,

Thanks
Dave

Transformer is M2853, and zener diode is Z3543 @ www.dse.com.au
.

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