bluefoxicy Posted February 19, 2019 Share Posted February 19, 2019 It occurs to me a 1:1 PT at 50VA costs only $10, while the PT on the Valve Jr costs $35-ish. With about $5 of circuitry, I can build an adjustable boost converter to get 170VDC-550VDC out. I figure $7-$8 will let me pull 5V-15VDC (filament) and 170V-550VDC (tubes), with the high-voltage followed by your standard power resistor layout, unless you want to spend $2.50 on a buck converter for each following stage (the capacitor becomes a filter capacitor). Drop in the $10 transformer and you've got a $20 PSU rather than the $45 one (PT + resistors) everyone uses. Components can be sized for like 300W so you can use a 300VA transformer for ~150W output. You CANNOT run a rectifier tube from the same transformer winding. It won't work. You'll short your amp out. Does that sound like a good piece for a DIY kit? I also want to build an OTL stage for the Valve Jr, but that's not generic. I'd need a different OTL stage for each type of amp, although I guess adjustable impedance matching would let me use the same stage on the same layout. Together that cuts about $50 off the DIY, I think? Quote Link to comment Share on other sites More sharing options...
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