Wow, Just Wow,
I remember not all that long ago if someone posted a schematic of that type here it would have been nearly instantly REMOVED from the thread.
I know I got warned years back for posting an old Kay schematic(which was removed).
The mere mention of a design of this type would never fly these days.
I remember not all that long ago if someone posted a schematic of that type here it would have been nearly instantly REMOVED from the thread.
I know I got warned years back for posting an old Kay schematic(which was removed).
The mere mention of a design of this type would never fly these days.
Well, that's all very true... there is no accounting for the actions of some idiots... which is why the kids' amp has included a GFCI 3-prong plug and Line-Fault Indicator for years.
It was a hideous idea sixty years ago, and it hasn't improved with age. How many sound cards, CD players, etc will survive 120Vrms? I'm sure a 1 : 1 PTX is a helluvalot cheaper. Even if you have to get two filament xfmrs and connect them back-to-back isn't so expensive.
We feel that safety should be inherent and not something you should test for.
Little Banger
OK, no line-sourcing... I get it, "We" don't do line-sourcing. So, if I am building to our Hundred Buck specifications, for the most bang for the buck I would convert that simple string-filament design with a pair of $8 "Isolation" Class-2 HVAC Transformers, added to that exquisite pair of $3 tubes and the $18 one-size-fits-all 8W iron... and it's still under a Benjamin.
OK, no line-sourcing... I get it, "We" don't do line-sourcing. So, if I am building to our Hundred Buck specifications, for the most bang for the buck I would convert that simple string-filament design with a pair of $8 "Isolation" Class-2 HVAC Transformers, added to that exquisite pair of $3 tubes and the $18 one-size-fits-all 8W iron... and it's still under a Benjamin.
35DZ8 List Price as of last check: AES $2.10, ESRC Vacuumtubes $3, Ebay $3.50, Vacuumtubes.net $4...etc not including shipping of course. Transformer-Pair was a left-handed suggestion in an earlier post ... but then I couldn't find a "good" 30VA+ 120:120 under $34 (which would likely move the cost est just too close to a C-Note) so I included the idea (tongue-in-cheek) in the line-source conversion. Anyway, with B+ at 90V or so, and driving deep (R5) into AB2, PO can top 5W. Also note conversion typos: C9 & C10 are 20uF & 40uF respectively, sorry for missing that... I'm old and only have one good eye left.
So where did you "get a good 120V:120V (40VA?) transformer for $12" ??
So where did you "get a good 120V:120V (40VA?) transformer for $12" ??
You can get a 50VA Triad N-68X isolation transformer from Mouser, and probably from other suppliers, for less than 12 USD ( but this does not include postage ).
I thought everybody knows about the two places with the $1 menu!
Vacuum Tubes - Audio Tubes - ESRC Vacuum Tubes - Electron Tubes
I have known Stan for over 20 years. He inherited the business from his father who I knew for a few years before he passed. I have been to his warehouse dozens of times. 4 million tubes is a lot. The 35DZ8 is $3
Vacuum Tubes Radio Tubes - 5,000 different tubes in stock - Over 10 million tubes!
I bought 1000 tubes off of their "Quantity Specials" list last year. They claim 12 million tubes in stock, but I have never been there, so I can't say. The 35DZ8 is $4
Vacuum Tubes - Audio Tubes - ESRC Vacuum Tubes - Electron Tubes
I have known Stan for over 20 years. He inherited the business from his father who I knew for a few years before he passed. I have been to his warehouse dozens of times. 4 million tubes is a lot. The 35DZ8 is $3
Vacuum Tubes Radio Tubes - 5,000 different tubes in stock - Over 10 million tubes!
I bought 1000 tubes off of their "Quantity Specials" list last year. They claim 12 million tubes in stock, but I have never been there, so I can't say. The 35DZ8 is $4
Not like I need more tubes, but now I have to look.
Checked EBay and I only found two listings for the 35DZ8, $8 a tube with $28 shipping and $20.50 with $8.20 shipping. But I've noticed I do not get listings that are only for the U.S. so I do not see all that is available out there.
My only saving grace is there is so much neat stuff that I can't decide.
The prodigal returns.
I won't derail the thread with a detailed account of all that's gone on in the last several months. Suffice it to say, I must have signed up for a lot of work on karma in my last lifetime -- multiple deaths in the family, a flooded home, and a spouse diagnosed with a chronic disease. Thankfully, the sh*tstorm has pretty much abated, and things are looking up.
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Once again, I'm going to modify the 'rules' and rewards of this challenge. Rather than choosing one design as better than all the others (a flawed premise from the outset), I've tried to identify those who kept this thread going and growing. No, this isn't political correctness, where everyone gets a prize simply for showing up. I scanned many pages, and tried to pick out a dozen people who truly formed the core of this discussion.
Obviously, Tubelab and Tubekit were the source of this (almost always) friendly competition. Printer2 also puts a great amount of thought and time into his well-illustrated posts. TheGimp, Trout, Scitizen17, Djgibson51, Costis_n, Cassiel, ChrisA, Jonnyeye, and Wavebourn all kept the discussion lively and interesting. Kevinkr, with his moderator's hat on, rounds out this baker's dozen of worthies.
If other readers or participants feel I've overlooked someone, please chime in.
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I too have 'magpie syndrome' -- except that my storage area looks like the last scene of 'Raiders of the Lost Ark'. So instead of paying the BOM tab for one 'winner', I'm going to ship a box of goodies worth at least $100 to each of the people listed above.
I have thousands of NOS tubes. hundreds of pounds of passive components, and many rare goodies to make A DIY tinkerer salivate. If you will tell me your preferences as to category of components, I'll try to oblige. Want sleeves of tubes? How about boxes of new aluminum knobs? Envelopes full of resistors, or bags full of polypropylene caps? Tubelab, I know you like high voltage. How about a huge potted UTC transformer, and matching choke, rectifiers, and HV sockets to construct a 1600v, 2200mA power supply?
Gentlemen, let me know your preferences, and a shipping address, in a PM. For those folks overseas, please be realistic -- I'll be glad to send you tubes or other lightweight components, but a box full of transformers isn't likely to come your way.
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I hope this twist is acceptable to all, and thanks for keeping things going while I dealt with much unpleasantness.
I sort of got my question answered.
Great thread, Well done guys