how can people post things this stupid?

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John Larkin                  Highland Technology Inc 
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John Larkin
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On a sunny day (Fri, 28 Feb 2014 20:26:30 -0800) it happened John Larkin wrote in :

So whats wrong with it?

Reply to
Jan Panteltje

"Jan Panteltje"

** ROTFL !!

You have your answer - John.

It's cos morons like this Dutch pig exist.

... Phil

Reply to
Phil Allison

Look at the header.

How can you get "single ended" and "push-pull" in the same heading, when in reality the topology shown is clearly a "complementary emitter follower" :-).

in practice, the Vbe losses would limit the power output to less than

5 W.
Reply to
upsidedown

Yeah, I mean, why would anyone even post links on a newsgroup to an awful article on a mediocre website?

Tim

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Reply to
Tim Williams

'Single-ended push-pull' was an oxymoron coined in the tube era, when two tubes were connected in series with output from the middle and with a single power supply voltage (that's single-ended here), and the push-pull came from active feed in both halves of the signal.

The bias chain is not too clever, either, burning 2 W.

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-TV
Reply to
Tauno Voipio

Setting two tubes or NPNs in series would be a totem pole output stage in TTL terminology, using (typically two 2N3055 in) series and driving the other would be a quasi-complementaryb output stage.

There is always the question, should the final stage only have current gain (complementary emitter follower) or also voltage gain in order to exploit VCEsat instead of VBE to reduce the voltage and power losses near the peak.

Reply to
upsidedown

** The stereo power amp I have been using since about 1980 has an output stage with 10dB of voltage gain using complementary (discrete) Darlington collector output.

This allows the PNP/NPN symmetrical drive stage to run from regulated +/- 18 volt supplies using 45V small signal devices. Symmetry gives low THD while the collector output stage has no tendency to thermal runaway despite no bias servo devices mounted on the heatsink.

A further novelty is whenever the output stage SOA limiter is triggered, it collapses both 18 volt rails and holds them down until the AC supply is cycled.

Lets you know instantly when you did something dumb ...

... Phil

Reply to
Phil Allison

On a sunny day (Sat, 01 Mar 2014 11:28:04 +0200) it happened snipped-for-privacy@downunder.com wrote in :

\>>>

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Yes, that description should have been 'singe stage' if I fell over every [journalist?] error like that I could scrap half of the internet too.

Sure, but it works.

I have used something like that, but also for cable driver without the diodes, and a series 100 Ohm (or whatever it was) resistor to match cable impedance, works great. I have send i2c data and clock across a whole building that way.

For hifi you probably want something else. I think J.L would like to quote [in this context] his MRI(was it?) current driver it has the output in the collectors IIRC.

That circuit is basically 100% OK. You can replace the diodes by a transistor and voltage divider too.

Reply to
Jan Panteltje

"Jan Panteltje Dutch Pig"

** ROTFLMAO !!!!

Wot a LYING blind as a bat wog pig.

... Phil

Reply to
Phil Allison

It was also "single supply". It doesn't look like a journalist's error - more like a dumb newby, which also fits the circuit.

So does the NE555

I imagine that it works. A more refined design would probably work better.

The circuit is basically 100% crude

It has been called a "synthetic diode" and usually includes a trimming potentiometer to allow you to set a standing current high enough to minimise cross-over distortion, but low enough not to waste too much current.

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See figure 8. The web-page is still pretty crude - my preferred class-A/B audio amplifier circuit used complementary Darlingtons - which seems to be what Phil prefers too (and his opinion carries rather more weight than mine).

With MJE2955 and MJE3055 power transistors it worked rather well. Motorola used a lot less silicon in the MJE3055 than RCA used in the 2N3055, but produced a much faster transistor, if one that was - theoretically - easier to blow up.

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Bill Sloman, Sydney
Reply to
Bill Sloman

John Larkin regularly posted awful articles on climate change from the Wall Street Journal, which makes a habit of publishing denialist propaganda on the subject.

Oddly enough, he never labelled them as stupid, relying on me to do that for him.

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Bill Sloman, Sydney
Reply to
Bill Sloman

Shows you where Larkin is looking for ideas >:-}

Actually, isn't this the sort of thing Larkin touted as a better solution than my automatically-biased class A-B amplifier? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

l

Seems unlikely.

Jim-out-of-touch-with-reality-Thompson doesn't seem to have noticed John La rkin's subject line "how can people post things this stupid?" which isn't a ctually touting it.

The "Unusual Bias Method" thread from the 25/11/2013 does indeed show a par ticularly evil biasing scheme, including an LM311 and just as many current mirrors as you'd expect from an integrated circuit designer. It seems to ha ve generated nine Google Groups pages of interaction and several "improved" versions from Jim, so it's not something you'd expect to see on a web-page for newbies.

I looked for a comprehensible explanation of how it worked in the thread (n ot something Jim is good at), but got bored before I found anything.

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Bill Sloman, Sydney
Reply to
Bill Sloman

Intelligent response shows experience or lack of it.

Output impedance will provide high dampening factor when load changes to a dynamic speaker with back EMF with applied pulses (like a kick drum sound) thus dynamic distortion of pulse will be reduced.

Can you calculate the dampening factor due to low base resistance?

Naturally this simple approach is inefficient, as with Class A-B, dampening factor and efficiency are tradeoffs.

Reply to
Anthony Stewart

On a sunny day (Sat, 1 Mar 2014 05:47:13 -0800 (PST)) it happened Bill Sloman wrote in :

Yes, good for a lot of things, unlike, well wha twas it yo uwere building ^H^H^H sorry dreaming of?

Well crude oil? LOL

Reply to
Jan Panteltje

On a sunny day (Sat, 01 Mar 2014 07:35:53 -0700) it happened Jim Thompson wrote in :

That oscilator?

I think J.L. coil river is neat.

Reply to
Jan Panteltje

Well, above a few KHz. Until the transistors fry.

Check their math, too!

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

What's interesting is how few people can do even minimally competant electronic design.

Amateurs can cook a decent pasta dish, lay a brick wall, build a bookshelf, or shoot a basketball. Even "professionals" can rarely do a decent analog circuit design.

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

The one that you posted didn't work either.

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John Larkin                  Highland Technology Inc 
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Reply to
John Larkin

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