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Tube rectifier PSU design for higher current?
Tube rectifier PSU design for higher current?
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Old 11th September 2019, 04:32 PM   #11
leadbelly is offline leadbelly  Canada
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You are right to have moved on but the OCD in me had to point out that TV damper diodes would have been the way to go.

Also, do you know about PSUD II? Better than a lot of iterative hand calculations.
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Old 11th September 2019, 04:56 PM   #12
Hifoli is offline Hifoli  Austria
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Yeah the TV dampers where a gleam () of hope but ultimately not the right thing for me.

I'm already toying with the PSUD. It's a great tool and I will surely use it to simulate my circuit, but at the moment I kind of throw "random" parameters into the filters and look at the outcome ^^

I'd much prefer to get the transfer function of my circuit and plot some graphs
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Old 11th September 2019, 10:04 PM   #13
leadbelly is offline leadbelly  Canada
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On a side note, are you sure you need to make a 1-2 amp supply? For an SS DAC? I'm having trouble imagining a DAC that needs that much.
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Old 12th September 2019, 12:07 AM   #14
analog_sa is offline analog_sa  Europe
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Tube rectifier PSU design for higher current?
Always been tempted to build a low voltage high current valve rectifier but unless one uses Tungar it is not easy. Valve rectifiers don't seem to enjoy working or sounding very good at low voltages. A few years ago built a 6D22S rectifier into a Salas reg in order to power up a Salas simplistic riaa. Did not sound particularly good at all. Otoh i use NL616 in one of my amps which is capable of a lot more than 1-2A. A series of regulators could bring the voltage down to dac supply levels. Perhaps i should give it a try.

Afaik the Brinkmann valve rectified supply works similarly: after valve rectification the voltage gets regulated down to 24v over several cascaded regulators. It is good for just 500mA but that can easily be scaled up.
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Old 12th September 2019, 12:41 AM   #15
wiseoldtech is online now wiseoldtech  United States
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I once got an "amplifier" in the shop that had a little window with two "tubes" behind it. Real tubes, no less.

The tubes glowed BLUE of course, because they had an LED under them. The tubes themselves were merely "hot glued" in place on a plastic bracket. This is the kind of crap you'll see from those asian companies - typical of the marketing attitude towards idiotic superficiality.

"Oh look, Henry!..... it's got TUBES!..... it's so NEAT!"
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Old 12th September 2019, 05:18 AM   #16
Hifoli is offline Hifoli  Austria
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Quote:
Originally Posted by leadbelly View Post
On a side note, are you sure you need to make a 1-2 amp supply? For an SS DAC? I'm having trouble imagining a DAC that needs that much.
Good morning
You are right to be suspicious, it’s a DDDAC with 4 dac boards (so almost 4 times the power of a standard dac configuration i guess) and it’s more around 1A.
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Old 16th September 2019, 06:06 AM   #17
opcom is offline opcom  United States
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575 or 673 MV rectifiers FWCT circuit, and regulate with two 7242 tubes in parallel.

The MV rects above are still $80 or less depending where you find them. count a 15V drop across the tube. 575 and 673 are same except base.

7242 triple-cathode triode can run with low drop also, and make 900mA. 100W anode.
- Power triple cathode triode designed as series regulator for power supplies. Similar to 7241 with higher mu. 100W total anode dissipation, mu 9, current limited to 300mA per cathode, 900mA total. Three cathodes with single grid and plate connections; hard glass bulb, 7 pin giant base. Sylvania and Tung Sol


575/A/673 data:
https://frank.pocnet.net/sheets/140/5/575A.pdf
take note of anode starting volts, transformer must supply this peak voltage.
rated 1.75A, or 2A if fil. is run in quadrature phase to anode.

7242 data:
https://frank.pocnet.net/sheets/127/7/7242.pdf
You probably want almost a 100V drop across the tubes, and take note of cathode equalizing resistors required.

Using a choke input filter for good regulation, plate transformer should be about 135V-0-135V. Adjustable taps on primary may help the experiment.

so, 135V -20V rectifier drop = 115V.
115V * 0.9 = 103.5V.
103.5V - 12V = 91.5V across regulators.

For 1A use two 7242s and two 673s
For 2A use three 7242s and four 673s (or run the filaments in quadrature and use two). Or try the NL616s as suggested. What is the starting volts on those?


It's not practical at all, but the point is "yes you can".
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