Re: filament trans.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mike Harrison by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mike-at-whitewing.co.uk>

I've found that by far the easiest way to get low-voltage, high
current supplies for filaments and the like is to overwind a new
secondary on a suitably sized toroidal transformer - the centre hole
is usually big enough to make adding up to a few tens of turns very
easy.

On Mon, 02 Jul 2001 18:28:15 -0600, you wrote:

>Original poster: "Metlicka Marc by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>
>
>hi all,
>for those looking for a filament transformer for there tubes in a vttc,
>i have made a nice one out of a 1000w 208\277v HID ballast transformer.
>i left the 208\277v primary in place a wound twin 12g windings around a
>home made bobbin for 12 turns each, this worked out to the 5v i need for
>my VT-127A'S. the trans. now gives me 5v from the 277v winding, 7.5v
>from the 208v winding, 10v from the two combined from the 277v winding
>and 15v from the two and the 208v windings.
>i left all the shunts in place because with the normal 330v-at-800ma
>output, the new windings should give 52 amp on the single 5v winding.
>much more then the wire will stand, i now wish i would have used 10 or 8
>g wire because i have the room. i have three more exact same ballast's
>so the next will use heavier wire.
>just thought i'd mention this cheap and easy filament transformer
>because most could get the ballast's from there local electrical
>contractors that deal with  high intensity discharge lamps.
>take care,
>marc m.
>
>
>