The OP is buying a kit that, according to the schematic, already includes a choke. And, a Triad C-14X (6H, 200mA, 150ohms) is £15+VAT in the UK, surely even cheaper in the USA. I would expect a new power transformer to be way more than that.
Reservoir cap for 5Ц4С should be no larger than 15uF, that must be a typo. But as others have said, your circuit draws more current than that rectifier can produce. Get your hands on a 5AR4 (check MagicParts.com) or go with the 2 diodes. Then you'd be fine with the 150uF caps in the power supply but you'd need a dropping resistor before the choke. Prob a big 2-350 ohm 10w wirewound.
GZ34/5AR4 specified max 60uF when used in cap input. Thus the 150uF has to go. As stated, convert to a LC powersupply
using 1n4007 / un4007 is the way to go here, then the 150uF is not needed.
To be honest I was surprised, good prices indeed, but still, $42 vs $18, not huge difference, but still a bit higher.
I don't know a lot about choke-input power supplies but I'm highly doubtful the cheap choke that comes with one of these chi-fi kits can be used like that. "Swinging choke" or something like that? Maybe it's not an issue with SS diodes.
The choke will have a lot more AC voltage across itself than when simply filtering, so it may "sing" noticeably, or not if you're lucky.
Freeing up the 5V winding allows it to be placed in series with the primary, to help "buck" modern line voltage. Both of these mods add stress to winding insulation, so it's especially important to make good metal-to-metal frame-to-chassis mounting connections, and to use a 3 wire power cord.
All good fortune,
Chris
Freeing up the 5V winding allows it to be placed in series with the primary, to help "buck" modern line voltage. Both of these mods add stress to winding insulation, so it's especially important to make good metal-to-metal frame-to-chassis mounting connections, and to use a 3 wire power cord.
All good fortune,
Chris
I haven't put anything into PSU designer yet. Maybe later today. I looked online for "representative" DCR for the transformer and choke. I don't need exact values right now, just a ballpark. So I came up with this:
example: Hammond 272FX power transformer DCR = 2.619 Ohms
example: Hammond 159S 4H choke DCR = 65 Ohms
target voltage = 315VDC
From a post above: Calculate using 150mA to keep some safety margins
- When I posted this yesterday, I had no idea what a "choke input" power supply was. That's one of the purposes of this exercise - for me to learn. I am trying to learn power supply design basics. I looked around online, and it seems that choke input was popular at one time. Why not now? Is the choke in danger of overheating or anything like that?
- In post #16, why use the 4.7uF capacitor in the CLC configuration? Why not leave it out, and why choose the value of 4.7uF? In my previous build of the Huaji Audio kit, many people suggested reducing the cap in that position to lower the output voltage. I never have understood why that is the case (smaller cap = lower voltage output) or what the disadvantages of that approach might be.
- Is 315V correct for this schematic? Should it be lower or higher?
I have obtained this photo of the inside of one that is sold already built. Sure enough, they do have it wired as in the schematic, and the transformer is marked 230 (115) VAC and 300V. It makes no sense to me as it seems that the rectifier tube would blow very frequently, like every 100-300 hours. I am left scratching my head on this one because the amplifier has been on the market for a long time. Perhaps rectifier tubes are so cheap in China that they just replace them constantly.
- What is the life expectancy for a good rectifier tube in a properly designed power supply? I haven't ruled out tube rectification if I can use a proper PS design and a reliable tube.
So many questions. Sorry. I'm trying to learn.
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Yes it's in kit form. I got it on sale very cheap, planning to do whatever mods are needed to get it to work. No great loss if I ruin it. It won't even be here for a few weeks.
It comes in many flavors and is sold by some very reputable sellers. https://www.aliexpress.us/item/3256804866757200.html
It leaves me scratching my head as it is.
It comes in many flavors and is sold by some very reputable sellers. https://www.aliexpress.us/item/3256804866757200.html
It leaves me scratching my head as it is.
Interesting. I read about this a while back. I don't remember why. Here is how to do it for anyone interested: http://www.diytube.com/phpBB2/viewtopic.php?t=3023
Yes, I learned about proper grounding when building the Huaji Audio kit and a Dynakit Parts ST-35. The Huaji Audio technically violates United States UL rules with many items connected to the ground screw from the power cord, but it's already built and impossible to change.
I need another amplifier like I need another hole in the head, but it's fun to experiment. I'm going to build another Huaji Audio (push-pull EL84) with upgraded components because it sounds so good. I'm trying to find an upgraded transformer set with end bells so I can leave the transformers exposed.
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Those rectifier tubes don't burn out every 2 weeks, don't worry about that. And if you're having so much fun building kits, why not build from scratch? Edcor makes nice pretty iron, in the States, too.
No reason it won't work as shown, but I wouldn't expect the rectifier tube to last very long. I'd just add the SS diodes that's already been suggested, and get it running
Not sure why.
jeff
Convenience and no fabrication, which I hate and don't do well. The chassis and PCB for the Huaji Audio are available separately, but I bought the second kit with transformers in case I can't find replacements with end bells. This SE kit was dirt cheap on sale, I have a number of EL34 tubes, and the money I saved on the sale will pay for any needed mods, including a power transformer if needed. I really don't want to go that far. I'm wondering if the "best" solution is implementing a tube rectifier that's more reliable, but I have no idea how many hours to expect from a good tube rectifier in a properly designed power supply.
I don't see how it can work with a massive overvoltage due to 1) The 110V transformer instead of 120, and 2) The voltage increase from removing the rectifier tube and using diodes.
Opening PSUdesigner now ...
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I found online that the American "equivalent" to 5Ц4С supposedly is the 5Z4, and I see a 5Z4-PA in PSUdesigner.
DCR of 2.619 Ohms? That can't be right? This arrangement in PSUdesigner produces a failure warning. I assume that I have it set up correctly as shown.
I figured there must be other people with different variants of this amplifier, and I finally found a long thread. https://audiokarma.org/forums/index...nd-rectifier-tube.848552/page-6#post-14377594
It seems that it's common to put two 150uF caps in the PS with the 5Ц4С, causing it to blow frequently. 5Ц4С appears to be only a $5-10 tube, so maybe they just plan to replace it every year, or in my case every few months. I'll read that whole long thread as it seems to have a lot of suggestions.
DCR of 2.619 Ohms? That can't be right? This arrangement in PSUdesigner produces a failure warning. I assume that I have it set up correctly as shown.
I figured there must be other people with different variants of this amplifier, and I finally found a long thread. https://audiokarma.org/forums/index...nd-rectifier-tube.848552/page-6#post-14377594
It seems that it's common to put two 150uF caps in the PS with the 5Ц4С, causing it to blow frequently. 5Ц4С appears to be only a $5-10 tube, so maybe they just plan to replace it every year, or in my case every few months. I'll read that whole long thread as it seems to have a lot of suggestions.
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2.6 Ohms sounds like the primary DC resistance. HV secondary will be lots more.
All good fortune,
Chris
All good fortune,
Chris
Yes, must be. Seems like about 75 Ohms is more realistic. So in PSUdesigner about 37 Ohms. This arrangement seems to produce about 300V instead of 310V. It also produces a warning due to the first 150uF cap.
Yes. As others have said, 150uF is way too much for HV rectifiers with a 10Watt filament, or for any gas filled rectifier (Mercury vapor, etc.). The issue is that current peaks exhaust the space charge, then try to strip cathode coating surface layer. Modern HV rectifiers are crap on a crust (for some unknown reason - why is it so hard to make rectifier diodes? - makes no sense), and need to be babied even more.
ps: a side note, a cLC may not be enough hum filtering for a single-ended amplifier. Much of the B+ hum appears across the OPT primary. Might want to make it cLCRC or even cLCLC if practical.
All good fortune,
Chris
ps: a side note, a cLC may not be enough hum filtering for a single-ended amplifier. Much of the B+ hum appears across the OPT primary. Might want to make it cLCRC or even cLCLC if practical.
All good fortune,
Chris
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