Who can/will help me with highvoltage SMPS design for tube preamp.

The smps is for tube preamps. For the classd part i have a very good hypex smps1200a400.
 

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I've been using current-fed push-pull DC-DC converters powered by a switching wall wart to run my VT preamp and headphone amp projects. I even have a moderate-sized SE amp using 6L6GC and 6AH6 powered by a medium-sixed DC-DC running from a switching 24V/5A adapter. The DC to DC circuits are all unregulated, and rely on the line/load regulation of the switching adapter that precedes them.
 
These days I favor a DC-DC approach for supplying power to a vacuum tube application, keeping the nasty AC interface in a box that already has the appropriate safety certifications . I would never market a straight AC to DC design due to concerns with safety and liability. The Chinese do it all the time, but that doesn't mean I have to....
 
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boyfarrell

Member
2021-05-15 12:25 am
UK
Well, yes, HVDC does kill people who don't watch where their fingers are poking, but there is a lot of due diligence that has to be performed to release an AC-DC power supply, including EMI compliance, safety compliance, line surge withstand, ESD resistance, etc. I doubt that most of the suppliers from over there have done due diligence. I would rather run a DC-DC off an SMPS from a major supplier that has the applicable safety ratings. There is too much that can go wrong otherwise.
 
These days I favor a DC-DC approach for supplying power to a vacuum tube application, keeping the nasty AC interface in a box that already has the appropriate safety certifications . I would never market a straight AC to DC design due to concerns with safety and liability. The Chinese do it all the time, but that doesn't mean I have to....
Seconded,

There is a Polish supplier that makes 12VDC to 450V 100mA flyback cores. The downside of this approach is higher primary currents, and EMI.

https://www.tme.eu/nl/details/ti-ef25-1068/pcb-transformatoren/feryster/

I made a 12V=>450V board some time back.
 

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This is the general form of the DC-DC converter I've been using to power various vacuum tube projects. I have various boards including the outputs necessary. For example, for a headphone amp project, the board will be a small one, with only the HV output, set for +150V, with the filaments of the project running from the switching adapter used to to power the project in question.. The higher power converter I'm using to power my 6L6GC/6AH6 single-ended amp uses the filament output at 12V and the HV output, set to 400 VDC, with a larger transformer to handle the power in question.

The DC-DC runs near 100% duty cycle, with a small amount of drive overlap programmed in so that the current-fed push-pull works properly. The regulation comes from the regulated SMPS used to drive the converter - this works well in practice, and the regulation is superior to that obtained from a conventional 60Hz transformer-based design.
 

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dreamth

Member
2010-11-18 9:12 am
T1 is unregulated...and its output depends entirely on the load. a resonant converter takes 2...4 trz , a coil and a capacitor plus same T1 and it's output is a sinus while having similarly regulated output only by the load.Your noise depends on the 12v source noise...
 
Using a transformer from a PC power supply in a DC-DC application might be problematic, It would depend on the topology of the donor power supply. If the donor supply uses a 1/2 bridge topoolgy, you might be OK, as there would probably be a center-tapped winding for the 12V output. If the donor supply uses a 2-transistor forward topology, there will be a single winding for the 12V output, probably stacked on top of the 5v output. This would be much harder to use as you envision.
 
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