Simple audio amp design

While I have some sympathy for the sentiment, I don't agree with the reasoning and conclusion. OTOH if it is solely for your sense of achievement, then that's a justifiable reason.

But why stop at discrete semiconductors? Why not go a little further and make your own inductors, capacitors and valves.

My father has a book describing how to make your own car - starting with how to make the tools necessary to make the car.

For you that may well be the case. You are obviously infinitely better at electronics than I will ever be. I know what I'm good at by this stage of my life and electronics doesn't come close, I'm afraid. It can never be anything more than a fascinating hobby for me. What never ceases to amaze me is how we each have different strengths and weaknesses in different subjects. People like yourself and John Larkin and Win Hill and our dearly departed (and much missed) Jim Thompson are at the top of the tree whereas I'm barely above root level. So it was fortuitous that I never went into electronics as a career or I'd have been a no-mark and still struggling whereas by choosing something I was far better suited to I was able to retire in my mid-40s. That at least was one of my better decisions! :-D Now I'm going to have a crack at doing the audio amp for myself. It's well within my ability after all, despite what I've said about myself above! :-)

Too true!

Sadly it's been many years indeed since old Bill ever posted anything relevant or useful to anyone here. Whatever he has to say is best ignored IMV.

Thanks again for your very welcome assistance, Jan; it's always appreciated.

CD.

In Curstor Doom's ever-so-expert opinion.

Since what Cursitor Doom posts is mostly links to Russia Today and Zero Hedge - lightly disguised as tinyurls - what ever else he has to say isn't going to be that valuable either. Jan was bitching about my posting two links to papers publiished in the Proceedings of the (US) National Academy of Science.

Unlike the stuff that gets published by Russia Today and Zero Hedge, they are at least peer-reviewed, not that Cursitor Doom understands enough to see that as a recommendation.,

Yes, why not? I recall there's an old book called something like 'desert island radio' which explains how to build a working comms radio solely from stuff you'd find washed up on a beach - including valves. Fascinating.

I'm really into that kind of thing. In theory at any rate.

The vacuum would be the interesting part of that.

I have a couple of Boy Electrician books with similar things. They also have sections on fun things you can do with your X-ray machine. They do presume you buy the tube, though, and warn you to stop if your skin starts becoming red.

I also have a book on how to make soap, and a Scientific American Cyclopedia (sic) of Formulas (sic). Everything from beverages to insecticides and a couple of dozen types of solder.

I'm well set pour "après le déluge".

Unfortunately life is too short to /do/ everything. We are lucky we have options.

Electronics is an incredibly broad field. The skills needed for high reliability design are very different to those needed to design low-cost products that are going to be commercially successful in high volume manufacture. Sometimes joining a collection of ICs together is the right thing to do. Other times, discrete design is more appropriate. There is a similar kind of tension between what should be implemented in hardware and what should be in software. Should the design be as good as it possibly can be or should it be "good enough"? Generally, there is no one right answer, but a continuum where different tradeoffs are balanced against each other. Just understanding those tradeoffs is in itself a valuable skill. So there is lots of room for different opinions. While their proponents often clash it doesn't mean that opposing views are wrong, just different and worth listening to as there may be insights to an open mind. I have learned a lot here.

John

i've built my own vacuum tube as an experiment long time ago. I even had (still have?) ideas about starting my own tube fab facility for audio amps. Alas, the tricks of the trade are probably too far buried in the past and the learning curve would be steep. I've read a number of papers from sylvania and rca engineers about some of their discoveries regarding material properties and their effects on tube performance. All of this would have to be 'relearned'. In any event, here is a video that I like a lot. It is helpful to have some of the equipment that he does, to build a tube: tack welder, vacuum pump, glass tube lathe, glass furnace, etc. it appears that even his electronic test gear is handmade. A real craftsman....

On a sunny day (Thu, 23 Dec 2021 19:03:13 +0000) it happened Cursitor Doom snipped-for-privacy@notformail.com wrote in snipped-for-privacy@4ax.com:

LOL as a kid I build a spark bridge transmitter from an ignition coil I asked a guy at school who's father was a radioham if he could ask his father if he could receive it (a few miles from where I lived). Man was he angry! So it worked!

It turns out you don't need a vacuum to get a thermionic valve to work.

No no no no no. Use new russian germanium trs where needed. See some of shango066 tr radio repair vids, some concentrate on tr replacement.

Whiskers can also be burnt away with a battery, but they do regrow.

On a sunny day (Fri, 24 Dec 2021 00:33:04 -0800 (PST)) it happened Tabby snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:

Interesting, nice video.

Most tubes used a mechanical vacuum pump and then a getter to clean up. Big beautiful transmitting tubes and PMTs and other high-quality tubes mostly weren't gettered, probably baked and pumped hard.

I had The Boy Scientist when I was a kid. Tons of dangerous stuff. I wonder if I can find a copy somewhere.

Yeah. I would have made a terrible peasant farmer.

Cheers, Tabbs. I'd forgotten about the Russian option!

snipped-for-privacy@highlandsniptechnology.com wrote: ============================== >

Turns white & powdery if air gets in, and vanishes if the tube seriously over heats.

...... Phil

Tabby wrote: ==============

Common light bulbs contain low pressure nitrogen but some small types have a vacuum inside.

IME regular electron tubes ( triodes / pentodes) fail to operate immediately when air leaks in.

..... Phil

To see what it takes to really make things from scratch see: "The toaster project". Most "make things from scratch" ideas require for example blast furnaces with their supply chain to provide high quality steel, etc. Even HD Thoreau uses a second-hand building for his Walden project. Wim

The idea of a settlement surving on Mars is absurd. There are no WalMarts, no Home Depots, no pizza joints, no trees for firewood. Nothing to eat or breathe.

Our civilization grew very slowly at first. You need a lathe to make a lathe.

lørdag den 25. december 2021 kl. 15.17.33 UTC+1 skrev snipped-for-privacy@highlandsniptechnology.com:

You need a lathe to make a lathe, but that's not *all* you need. The guy in the video uses wood to get around this problem, but if you wish to make a serious metal turning lathe, you will need some means of producing castings for the turned components such as shafts and bearings to be stably held. And for screw cutting, you then need some way of making gears as well. You can't make a practical metal-turning/screw-cutting lathe without castings, a mill and various cutting bits additionally. And the cutters require a grinder to put an edge on 'em. It's therefore not as simple as Bill Sloman suggested^h^h^h^h^h^h^h^h^h^h. ;->