A couple of measurements I made in a spare hour:
Philips 330uF 400V electrolytic (about 2 yrs old). I measured without dc
bias on the cap - series resistance at 2MHz is a few tenths of an ohm,
rising to about 1 ohm at 50MHz. At these resistances the network
analyser (HP8714C) is not at its most accurate, but it reads a 1 ohm
resistor to within 5% over the range, so I doubt the figures are
massively out.
A couple of microwave oven transformers. I lifted the 'ground' end of
the ht winding on both and put them on hipot. One (much bgger than
standard) is happy at a prolonged 10kV. I put some Kapton tape under
where the wire comes out on the other, and it's good to 8kV+. In other
words, both appear suitable for normal use with a bridge rectifier. I
know they have their limitations, but given they cost *nothing* it's
good value for money! I couldn't recommend using a floating winding
without the hipot test, but it's clearly worth the effort of trying.
Steve
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