using mains voltage taps for bias> bad idea?

[black_labb]

say i had a power transformer without a bias tap, but there were taps for the power in that were 0-200-230-240. i will be using the 0 and 230 for the input voltage. would it be unsafe to use the 200 and 230 (30v) or 200 and 240 (40v) for the bias tap?

[Enzo]

Well, I sure wouldn't. Your bias would than be at mains potential. You need the bias to reference ground along with the rest of the circuit, but you don't want the mains grounded in any way.

This would be a very bad idea.

One way you COULD do it would be to use an isolation transformer. Those are 1:1, and across 200 and 240 there would be 40v, and the transformer would then put out 40v on the other side, but it would no longer be connected to the mains. But if we were going to do that, why wouldn;t we just get a transformer that spit out bias voltage in the first place?

[black_labb]

thanks, thought that might be the answer.

[stokes]

Why not just tap the HV secondary,like this http://schematicheaven.com/ampegamps...gemini_iv.pdf?

[black_labb]

exactly what im going to do. thanks.