as you can see, i wound my primary and grid coils on a cut off piece of the fiberglass tanks i show on another page on this site. since the filaments for these tubes require 5volts@10 amps each, i built a filament transformer from a ballast transformer out of a 1000 watt high intensity discharge metal halide light unit. these ballast transformers can be had by contacting your local lighting or electrical contractors that service comercial\industrial lights. many times it is more cost effective to change the whole light unit then to try replacing the insides to get them to work again, so if you ask nicely they may be had for free?

so i cut the welds of the core and removed the secondary, the ballast i had was for 208\277v use so the primary had the two taps, this was going to work great for a filament transformer i thought? i proposed winding two secondary coils together on the core, each one wound in oposit directions so that center tapped and wound with what came out to 14 turns of 12g thhn wire to give me 5 v on the 277v primary tap. first thing i did was to make a bobbin for the windings out of high voltage cardboardy type sheet i had, i made it square and super glued the top caps onto the cut and folded tabs. this i hoped would give me a high voltage isolation value insulation layer to the core? as i wound a layer of the secondary, i wrapped a layer of fiberglass tape over each layer to hold it in place and to give an insulation layer, layer to layer. i wound the two windings oposed and finished it out by checking the output voltage as i went, i held the L\T core elements together with a clamp and conected 120v to the 277v winding then measured the output at the ends of my 12g wire. at 16 turns my voltage was 9v or something? so i removed windings and kept checking until i hit the magic 5.4v from each secondary lead. then i cut the 12g secondary wire to length, fiberglass taped the new windings solid in place, and went to the garage and clamped my cores in the vice and fired up the mig welder to get it back together.

when i brought it in and conected 120v to the primary 277v tap, the transformer buzzed like crazy??? i narrowed it down to the fact that the original shunts in the transformer were epoxyed in place so when i cleaned everything up i removed the epoxy, my solution was to tack weld the shunts in place, worked great, no NOISE at start up (hurray).

the center tap idea worked great, with the 277v primary with 120v input, i get 5v output from each secondary winding. with both secondary windings tied together i get 10v output, with 120v input into the 208 winding i get 7.5v output from each secondary winding and 15v with the two tied together.

with the original shunts in place i calced output at a possable 25 amps, but it seems i may be mistaken? i'm only getting 8.5 amps pulled by the two filaments of the tubes? i'll have to short the secondary leads to see what my peak currents for this "HOME MADE WITH PRIDE" filament transformer.

i suggest this type of unit to anyone that hasen't got one of those fancy filament transformers laying around. some say that one wound on an mot core works just as good, but i think they are missing the point about the multi-tap primary giving me 5, 7.5, 10. and 15v for a broad range of filament voltages.


	vacuum tube coils i finaly researched enough information, and gathered enough doodads to feel confident in building my first vttc (vacuum tube tesla coil). i started by choosing a relativly low powered tube set that i bought off of ebay, these VT-127A'S are a unique looking triode that has duel taps for the plate and the grid as you can see this strange looking tube just "HAD" to be "ME" for my first atempt at oscilated sparks. i decided to use david trimmels schematic for using an mot (microwave oven transformer), it is a very simple design that i would recomend to any that wish to dabble in the vacuum tubes. i substituted the 803's with my tubes in this schematic. (All the componants on one floor) as you can see, i wound my primary and grid coils on a cut off piece of the fiberglass tanks i show on another page on this site. since the filaments for these tubes require 5volts@10 amps each, i built a filament transformer from a ballast transformer out of a 1000 watt high intensity discharge metal halide light unit. these ballast transformers can be had by contacting your local lighting or electrical contractors that service comercial\industrial lights. many times it is more cost effective to change the whole light unit then to try replacing the insides to get them to work again, so if you ask nicely they may be had for free? so i cut the welds of the core and removed the secondary, the ballast i had was for 208\277v use so the primary had the two taps, this was going to work great for a filament transformer i thought? i proposed winding two secondary coils together on the core, each one wound in oposit directions so that center tapped and wound with what came out to 14 turns of 12g thhn wire to give me 5 v on the 277v primary tap. first thing i did was to make a bobbin for the windings out of high voltage cardboardy type sheet i had, i made it square and super glued the top caps onto the cut and folded tabs. this i hoped would give me a high voltage isolation value insulation layer to the core? as i wound a layer of the secondary, i wrapped a layer of fiberglass tape over each layer to hold it in place and to give an insulation layer, layer to layer. i wound the two windings oposed and finished it out by checking the output voltage as i went, i held the L\T core elements together with a clamp and conected 120v to the 277v winding then measured the output at the ends of my 12g wire. at 16 turns my voltage was 9v or something? so i removed windings and kept checking until i hit the magic 5.4v from each secondary lead. then i cut the 12g secondary wire to length, fiberglass taped the new windings solid in place, and went to the garage and clamped my cores in the vice and fired up the mig welder to get it back together. when i brought it in and conected 120v to the primary 277v tap, the transformer buzzed like crazy??? i narrowed it down to the fact that the original shunts in the transformer were epoxyed in place so when i cleaned everything up i removed the epoxy, my solution was to tack weld the shunts in place, worked great, no NOISE at start up (hurray). the center tap idea worked great, with the 277v primary with 120v input, i get 5v output from each secondary winding. with both secondary windings tied together i get 10v output, with 120v input into the 208 winding i get 7.5v output from each secondary winding and 15v with the two tied together. with the original shunts in place i calced output at a possable 25 amps, but it seems i may be mistaken? i'm only getting 8.5 amps pulled by the two filaments of the tubes? i'll have to short the secondary leads to see what my peak currents for this "HOME MADE WITH PRIDE" filament transformer. i suggest this type of unit to anyone that hasen't got one of those fancy filament transformers laying around. some say that one wound on an mot core works just as good, but i think they are missing the point about the multi-tap primary giving me 5, 7.5, 10. and 15v for a broad range of filament voltages. ok so with the transformers and capacitors gathered up, the primary wound to a few turns over what wintesla suggested for my little test coil