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Registered Member #3324
Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276
Hey 4hv!
my first vacuum tube has arrived today, its filiment is 20v @ 3.5A max (GK-71) ive been looking for a transformer for this but i havent found any so far anyone got any good ideas on what i can do about this?
thanks, Thomas
EDIT: im trying to make the capacitor feedback, how do i cut 0.5mm copper?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
The best way is to rewind one, you can find transformers of such power rating everywhere, just select one which will looks like the core can be easily disassembled.
Registered Member #3324
Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276
Great, had a look through all of my transformers, most of them are worth too much to rewind or just unsutible (the primary appears to be wound ontop of the secondary)
Registered Member #5436
Joined: Sun Jun 24 2012, 01:44AM
Location:
Posts: 39
Hi,
Use a slightly underrated 24 volt transformer. With a bit of luck, it should drop down to 20-20.5 volts. It shouldn't overheat with the short run times of a vttc. Or use a suitably rated transformer and a varaic.
Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
how about a smps? if you go with a nice fully built ic like the lt1070 you can easily get that power. plus because it has antergrated fets, the parts count is ~5. i built a usb to power dc-dc for testing of high voltage stuff off of a computer supply. it can out 9-28v at a really nice current rating limited only by the usb 500-1000mA. if you where to power it off of a 12-18vdc source with 3-5A, you'd get your desired specs.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I wouldn't use a complex and interference-prone SMPS in an otherwise very simple and "forgiving" circuit of a VTTC. But it is everyone's thing I guess...
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My First Tube! :D
