An electronic question.

[Roger Hayter]

The paradox is explained when you note that the article is 20 years old and the 741 50+ years old *now*.

[Roger Hayter]

No, I don't know where that 20 years went either!

[Peter Able]

Which all but NatPhil seem to have understood. I'll try to write more inclusively next time ;-}

PA

[Peter Able]

That is because it is not a quote. When I quote I follow the convention of quotation marks - so I might have quoted such technical expressions as "rubbish", "more rubbish", "unmitigated drivel", "frauds and charlatans".

And you?

PA

[Peter Able]

And it has some C at the LV output(s)?

PA

PS those of us in engineering at that time were so grateful to see the

741 kick the 709 out of designs.

[Peter Able]

Or Russ Andrews !

PA

[Peter Able]

Indeed Bell Labs would have. Vis-a-vis perceived lifetimes, the 2N3055 is on its state pension by now - but still a useful device to have in the junk box. Go back the same number years from the 12AX7's birth date and you are back in Victorian times!

PA

[Peter Able]

We're obviously of a similar age. When I won a book prize at grammar school I nominated that as the prize. The school was scandalised! "No one has EVER been given a paperback book at Speech Day!!!!". The compromise was that I choose a conventional book (a hardback Latin dictionary), as well.

I still have both. You can guess which is the more thumbed !

PA

[Fredxx]

I'm struggling to see this phrase. A word search finds 3 'year's as part of 2 'many years" and one "over the years". A search of '50' finds 4, none of which pertain to time.

FAOD the article was revamped in 2021. Perhaps they frequent this newsgroup and updated it in the past day or so? Rod? No, he claims to be a chemist.

Many op-amps are effective Class B outputs, where pulses in current occur when the output is changing.

DRAM is relatively simple to decouple. There are models that predict voltage dips and resonant behaviour for multiple decoupling capacitors on power pins with multiple value.

The design voltage ripply for DRAMS would be somewhat higher than levels preferred for audio.

What outputs? I would hope regulator outputs. It's normal to use a mix of types, though high value ceramic is sometimes used alone.

That would be difficult to argue. I note on some equipment the valve is there for pure show, and while the heater is glowing all they are producing is heat.

[Fredxx]

From what I can read I can't see any reference to 50+ years and the article was revamped in 2021.

BTW, the Transistor was invented in 1947.

It's perhaps ironic they were trying to fabricate a J-FET and that Julius Lilienfeld is credited with the first patent on the FET in 1925.

I'm sure some transistors in Bell Labs in 1950 would have some characteristic that would beat a 12AX7. Size might be one, though the first ones had a hefty package.

Hell, the 12AX7 was only 'invented' in 1946.

[Peter Able]

We've both commented on the life of the 2N3055, so there's common ground there.

The 741 was surpassed 40 years ago, the improvements made since being absolutely relevant to this article.

The article's quality is not helped by its use of terminology such as "rubbish", "more rubbish", "unmitigated drivel", "frauds and charlatans".

I've written extensively for the technical press - but never in terms of obsolete components - or using such foolish expressions. Personally, I'd steer well clear of those who do.

PA

[Fredxx]

Perhaps Rod Speed is AKA Rod Elliott?

[charles]

we certainly had transistors when I was at school - late 1950s and my copy of "Mullard Manual of Transistor Circuits in dated 1961. That's 60 years aago.

[Fredxx]

I just don't get your point, "An article originated 2000, referring to a

50+ year old Op Amp design (great advance though it was) is the first hint".

The uA741 is still in production, and the 741 is the ubiquitous op-amp.

"SLOS094G? NOVEMBER 1970 ?REVISED JANUARY 2018"

A bit like a 2N3055 is to a power bipolar npn transistor.

Referring to circuits that have survived the test of time should give credibility to an article, not one that should be taken with a "pinch of salt".

Please explain why this article should be taken "with a little pinch of salt"?

[Fredxx]

I see what you mean. Perhaps I take a greater issue with those perpetuating myths, and brushed these phrases aside as being more appropriate for Joe Public.

They are not words I would choose either.

[Theo]

Nitpick: you attack noise at the source of the noise. Noise generated by the power supply should be attacked at the power supply, as you say. Noise generated on the power supply rails by other components should be attacked close to where those components are.

The reason is that the power supply wiring has a certain impedance at the frequency of consideration (due to 'parasitic' R/L/C). The further you go from the source of the noise, the higher the impedance to reach it. And any mitigation you put in is less able to work effectively because of that impedance.

This is the reason for the folk wisdom of always fitting a 0.1uF capacitor next to every IC - it has the minimum trace length and so the minimum impedance to being able to damp current spikes from that IC switching.

(PDN analysis is a thing you have to do when the design is a bit more critical, can avoid instability, and can also save you money on unnecessary components. But folk wisdom gets you a long way if you're not manufacturing in volume)

Theo

[Theo]

:-)

My chosen prize was 'The Art of Electronics'. When I won the prize the next year there was nothing else to top Horowitz and Hill, or at least that could be found in the Charing Cross Road branch of Waterstones (the prize unhelpfully provided in Waterstones vouchers, and Waterstones being truly useless at technical books). So I had to settle for something less useful.

Likewise :)

Theo

[Dave Plowman (News]

Of course. Every decent regulated analogue PS for audio I've seen has C across the rectifier and the output.

[Dave Plowman (News]

Elliot's stuff may be a bit self opinionated, but generally sound advice for those they are written for.

[Bob Martin]

Second edition? That's the one I have, given to me by RAF Yatesbury.