I'm feadup with replacing the batteries on my multimeters so I'm thinking about building a miniture mains powered multimeter power supply to power two meters with. I'm planning on using a small twin secondary 9V transformer and adding two separate rectifiers, smoother caps, and linear regualtors to each secondary.
The only question is, what's the minimum withstand voltage between the transformer's secondaries?
I know it's rated for double insulation and therefore can take 2kV between the primary and secondary but it doesn't say anything about the secondaries.
I'm concerned about this because the situation might arise when I'm using both meters to measure voltages on different parts of a mains circuit, so one might be floating at 340VDC and the other at 0V.