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Tube rectifier PSU design for higher current?
Tube rectifier PSU design for higher current?
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Old 4th September 2019, 04:22 PM   #1
Hifoli is offline Hifoli  Austria
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Default Tube rectifier PSU design for higher current?

Hi there, I'm pretty new here and are just getting my feet wet in the DIY PSU world


I'm looking to build me a PSU with a tube rectifier but I need 12V at 1~2A output. So I already figured out that this is not an easy task ^^
I was wondering if there is a way to do it. Like with a hybrid bridge or paralleling 2 or more tubes.

If it's not possible or would lead to a completely stupid design, what would be the nicest/cleanest design alternative?


Any tips are very welcome
Thank you in advance!
Hifoli


PS: PSU is for a DAC-Board
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Old 4th September 2019, 04:37 PM   #2
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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Actually there is no solution for those requirements. No normal (reception tubes) are capable of giving 12V @ 1A.
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Old 4th September 2019, 08:11 PM   #3
kodabmx is offline kodabmx  Canada
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Tube rectifier PSU design for higher current?
It's called a Tungar. It's a gas tube they used to charge batteries...
http://www.r-type.org/pdfs/tungar.pdf

Just use barrier diodes LOL

Last edited by kodabmx; 4th September 2019 at 08:13 PM.
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Old 5th September 2019, 01:06 AM   #4
PRR is offline PRR  United States
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Quote:
Originally Posted by Hifoli View Post
....tube rectifier but I need 12V at 1~2A output....
The drop of a vacuum rectifier can be over 100V, and no ordinary vacuum rectifiers are rated over a part-Amp.

The derivation attached is inexact, and 5U4 is not the biggest bottle, but was always a go-to for big amplifiers. You need nearly 200V in, and five bottles, to get 12V 1A out. The rectifier heats-up with 15 times the power that your DAC eats, about 180 Watts in plates. +Plus+ another 75 Watts in filaments.

And it will be far too saggy for powering digital chips. Building a vacuum Regulator at 12V 1A is even more "stupid".

Use solid-state and nail a bottle to the top.
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Old 5th September 2019, 01:16 AM   #5
kevinkr is offline kevinkr  United States
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Tube rectifier PSU design for higher current?
A pair of tungar bulbs will work in a FW CT configuration, but are impractical and ridiculously inefficient. 25A each @ 2.5V for heating power is typical. At 1A they will drop a few volts. I have some limited experience with them for field coil power supplies, but would not recommend them to a newbie.

They are still available new in China of course..
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Old 5th September 2019, 02:22 AM   #6
multi-volti is offline multi-volti  United States
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That GE scientist pictured in the Tungar book with liquid chemicals had no safety glasses. I hope he had a long safe career. Maybe that was one of Edison's people trying to find non-conducting filaments for incandescent lamps.
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Old 5th September 2019, 07:37 AM   #7
Hifoli is offline Hifoli  Austria
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Quote:
Originally Posted by PRR View Post
The drop of a vacuum rectifier can be over 100V, and no ordinary vacuum rectifiers are rated over a part-Amp.

The derivation attached is inexact, and 5U4 is not the biggest bottle, but was always a go-to for big amplifiers. You need nearly 200V in, and five bottles, to get 12V 1A out. The rectifier heats-up with 15 times the power that your DAC eats, about 180 Watts in plates. +Plus+ another 75 Watts in filaments.

And it will be far too saggy for powering digital chips. Building a vacuum Regulator at 12V 1A is even more "stupid".

Use solid-state and nail a bottle to the top.
So silicon bridge is probably the way to go for the DAC. Sad i would have loved some blue glowing tubes Perhaps I can put the "normal" rectifier tube into the reclocker PSU I'll build (5V, 100mA) so I can nail the tube on top and also use it ;D
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Old 6th September 2019, 11:28 AM   #8
kodabmx is offline kodabmx  Canada
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Tube rectifier PSU design for higher current?
The only rectifiers that glow blue are mercury types like 83 and 82... They are very noisy apparently.
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Old 11th September 2019, 11:45 AM   #9
Mark Tillotson is offline Mark Tillotson
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Originally Posted by Hifoli View Post
So silicon bridge is probably the way to go for the DAC. Sad i would have loved some blue glowing tubes
Fake it with blue LEDs then??!

Thermionics doesn't do high current densities I'm afraid. Gas tubes are something else, high current densities are available, but not at low voltage, for instance mercury rectifiers used to be the main high power device years ago.
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Old 11th September 2019, 04:22 PM   #10
Hifoli is offline Hifoli  Austria
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I wanted to put the tube rectifier in it bc my preamp and amp are tube based and I liked the idea of having one in the DAC section but you are right: tubes are not suitable for low voltages.

So I already threw the idea and am now looking into silicon/schottky for the rectifier and some kind of LC filter after that.

So as I'm into math and numbers I'm now looking into circuits and transfer functions (although it seems its more like going throgh transformer/choke manufactures catalogues to see what one can find that gets close to what one needs and then build around that ^^)
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