>When you want both supplies to live independant, you have to feed them
>independant.
>Try this: connect the middle of the transformer windings to ground, use 2
>buffer elco's in series, the middle to ground. Your supply will work
>perfect, up to 15V+-

Sorry to be ignorant, but what exactly *is* a 'buffer elco'?

>I believe your problem is the bridge recitifiers.  A bridge rectfier circuit
>produces  floating outputs.  What you need to use is either a half or full wave
>rectifier circuit with the ground attached directly to the transformer winding.
>This will keep the ground from floating and keep your power supplies from
>tracking each other.   If you can arrange your transformer secondaries into a
>center tap configuration, then use this center tap as the ground.  Once this
>grounded center tap is in place, use full wave rectifiers to produce your
>positive and negative supplies.

I think both these replies are saying similar things, but before I devastate
North Norfolk with a huge explosion - can I treat a transformer with dual
secondaries wired in series as a centre tapped transformer, and earth the
'middle' of the coil. If that makes any sense.

Many thanks

John Midgley