Quote:
Originally Posted by wa2ise
Such isolation transformers still need to be safety rated. I think it calls for the ability to take 1.4kilovolt DC "HiPot". Seems that that's above the biggest expected transient spikes one usually sees on the powerline.
|
Most transformers (at least with the "CE" mark) already meet or exceed this. Urethane varnish 4 mils thick has a dielectric strength around 1.8KV, making it quite easy to meet the spec. I'm no engineer, but anybody who's ever seen the transformer in an Asian wall wart can see that HiPot ratings aren't too difficult to achieve even with the lowest grade materials.
I'm not advocating cutting corners, just comparing methods used to achieve the same results. Me, I'd stick to a thermally fused isolation transformer (faraday shielded - we're talking AM reception!) at the AC end of things, and an interstage transformer wired in to provide audio isolation/ground loop avoidance. Just my fantasy build. I'd
never "fishtank" an antique/old/tube radio by lashing it up for some fad-driven ipod.
Cheers,