Distortion in darlington amplifier

[be80be]

Now that's funny I posted links to all of it and I posted full circuit from where it all came from.
I'm not posting for right or wrong I'm just letting the world see where this comes from.
I didn't post how to fix my chopped off Amp you did

And people did try to help some may harsh at it LOL but as you said you new it all why even ask then. I know I don't know it all this new day for me but im not going to ask for help then kill any chance of getting it LOL

published in the journal "Radio" No. 11 - 1959

 

[Stan2020]

Glad I made you lough. When I _do_ get help, I am always very grateful for that. When instead of help I am getting accusations, contempt, arrogance and BS - thank you, keep this 'help' for yourself.
But all this is an off-topic, I am out of here.

 

[gophert]

from professionals I'd expect them listen to the arguments regardless of how I introduced myself. For professionals the subject means way more then personal ambitions. For professionals, when someone disagree with them, they listen and try to understand first. They don't throw arrogant claims ' stupid and useless', ' found on some young kids webpage' etc. But this is for professionals. Enjoy your self-importance.

I think your issue is an expection that Engineers act like professional Therapists, Artists, Teachers. Sorry, engineers are not the hand-holding compassionate types you want us to be.

 

[unclejed613]

for the passive sections of your radio (input tuning, coupling between RF amp stages, and detector) you may find chapter 9 and 10 of [this book] worth reading. it was written at a time when vacuum tubes were a new invention, and a lot of work had gone into maximizing the performance of the RF stages WITHOUT amplification. the same techniques can be applied to RF amplifier stages and the detector stage. one thing i found interesting was the use of DC bias on the detector diode to bring it right to the edge of conduction and make the detector more sensitive.

 

[be80be]

I've read that book years ago thanks for posting unclejed613

 

[Mickster]

For professionals, when someone disagree with them, they listen and try to understand first.

You haven't tried to behave in a professional way yourself, when someone has disagreed with what you have posted......your 3rd post in was confrontational, based upon critical observations made of the content within your 1st and 2nd posts.....which were not even your own work....YOU were not being attacked, the circuits that you had referenced were. Wind your neck in a bit.

 

[throbscottle]

Don't assume they're knowledgable. There's a lot of copying going on without much understanding. I saw a kid get a job as a researcher at a university with a fundamentally flawed understanding of basics...Like he claimed an improved accuracy of a fixed frequency source by dividing down the clock. WRONG!

I draw comfort from this...
Though shoving the error down the dp's has it's uses, doesn't it?

 

[throbscottle]

one thing i found interesting was the use of DC bias on the detector diode to bring it right to the edge of conduction and make the detector more sensitive.

The cracks in some carborundum detectors were observed to glow due to their bias voltage, making them effectively the first LED's.

 

[rjenkinsgb]

Looks like I should have entered as others self-proclaimed "professional electronics engineers and designers" here

I can't speak for others exact qualifications, but for me it's almost 50 years professionally designing, programming and manufacturing electronics in fields covering everything from RF, analog and digital audio through robotics, factory automation & machine tools.
[My own business, starting before I left school].
Plus holding a UK Amateur since 1979.

Re. that receiver, the only way to be sure how it worked is to see the original physical construction, which is not shown in the article you posted.
If L6 is parallel to L4/L5 then it's regenerative.
If it's at 90', it's TRF or intended to be reflex - but the R2+C3 time constant and general bias arrangement does not fit with reflex, to my interpretation; it appears more like a combined detector / AGC system in that case.
Or the RC combination could be deliberate frequency compensation to suit a particular speaker/earpiece.

Re. "attitudes" - you said:

reproduced in thousands in1960th...although even today there are hot arguments on how and why actually it works

Then later you make categorical statements of fact of how it supposedly works!

 

[throbscottle]

It does mention on the longer web page that a telephone earpiece was chosen rather than a regular speaker, so it could have been (quick google) around 150 to 450 ohms

 

[schmitt trigger]

I believe that you are correct, thobscottle. Either that or crystal earphone.

Otherwise with an 8-ohm dynamic speaker, there would be a HUGE dc current flowing thru the speaker's coil.

 

[Nigel Goodwin]

I believe that you are correct, thobscottle. Either that or crystal earphone.

Otherwise with an 8-ohm dynamic speaker, there would be a HUGE dc current flowing thru the speaker's coil.

A crystal earpiece probably wouldn't work in that circuit, as there's no DC path through it to power the transistor.

I imagine, based on the date, it was more likely a pair (or one of) 2000 ohm headphones.

The obvious issues with the circuit are simply because it's too old, and (from what has been said) often didn't work even back then. It was simply before people knew how to use transistors, and they diodn;t know any better.

 

[throbscottle]

Specifically, it says:
Нагрузкой выходного каскада служит обмотка электромагнитного громкоговорителя, в качестве которого используется капсюль ДЭМ-4М. Для приемников бытового назначения такого класса частотная звуковая характеристика не столь важна. Поэтому решено было отказаться от переделки капсюля ДЭМШ-1 в громкоговоритель, а применить доступный распространенный телефонный капсюль.
Вариантом экономичного однотактного выходного каскада с нагрузкой на высокоомный капсюль может быть и применение режима плавающей рабочей точки (2). Существуют и другие варианты - схемы однотактного выходного каскада с применением малогабаритного трансформатора или бестрансформаторного выходного каскада (2). В этих случаях можно применять обычные низкоомные малогабаритные динамики. При этом качество воспроизведения заметно повысится.
Google translates this as:
The load of the output stage is the winding of an electromagnetic loudspeaker, which is used as a DEM-4M capsule. For consumer receivers of this class, the frequency response is not so important. Therefore, it was decided to abandon the conversion of the DEMSh-1 capsule into a loudspeaker, and to use an available common telephone capsule.
A variant of an economical single-ended output stage with a load on a high-impedance capsule can also be the use of a floating operating point mode (2). There are other options - single-ended output stage circuits using a small-sized transformer or a transformerless output stage (2). In these cases, conventional low-impedance small-sized speakers can be used. At the same time, the playback quality will increase significantly.

So they are talking about a modern re-construction of the circuit where a "telephone capsule" was used. I wonder what the DEM-4M and DEMSh-1 capsule were?

It also mentions using a transformer output, which seems to be something everybody has been avoiding mentioning over the entire thread. I used to love those little speaker transformers!

Right, now I'm off to learn Russian, I keep encountering interesting Russian things more and more these days...

 

[atferrari]

Chinese better; go for the Chinese language.

 

[throbscottle]

Yes, I should definitely learn Chinese too! Not only do I keep coming across stuff on the web in Chinese (and Google translate isn't quite enough), also I'd like to know what they are really saying, chatting away in the kitchen of my local takeaway! I missed out on the chance to learn Latin (which I though would be interesting) when at school because I wasn't good enough at French (which I had no interest in at the time). Stupid system. So that's also on my list.

It occurred to me that it might be a good idea to learn Russian and Greek side by side since they share some letters, I don't know but it seems likely they share other things too.

So far I have properly attempted to learn (as an adult) French, German, Hebrew, Japanese, also started a book to learn Spanish (something happened, I didn't continue) and picked up a very little Greek during childhood holidays. At one point I could read the Greek words even if I didn't know what they meant. Wanting to get back into them all but night classes don't really work well for me. It occurred to me last night (and I got so excited about it I couldn't sleep) it might be possible to start a local "mixed language practice group" where everyone has at least one language they'd like to practice, everyone brings something to the table and everyone gets to take something away. Everyone gets to be both student and teacher. I'm going to dig down into the idea some more at least.

 

[audioguru]

As an adult I went to night school to learn Spanish so I could communicate with my Spanish wife's parents. On day one everyone else was fluent in Spanish except me. They all went there to meet Spanish people, not to learn Spanish.

 

[Nigel Goodwin]

Yes, I should definitely learn Chinese too! Not only do I keep coming across stuff on the web in Chinese (and Google translate isn't quite enough), also I'd like to know what they are really saying, chatting away in the kitchen of my local takeaway! I missed out on the chance to learn Latin (which I though would be interesting) when at school because I wasn't good enough at French (which I had no interest in at the time). Stupid system. So that's also on my list.

EXACTLY the same situation at my Grammer School - in the first year you did French, in the second year and above you had the option to also learn either German or Latin as well, but only if you were good enough at French. I suppose the reasoning was that if you weren't good at learning French, then you wouldn't be any good at learning another language either.

I was crap at French, so was only allowed to continue doing French (which I failed!).

So far I have properly attempted to learn (as an adult) French, German, Hebrew, Japanese, also started a book to learn Spanish (something happened, I didn't continue) and picked up a very little Greek during childhood holidays. At one point I could read the Greek words even if I didn't know what they meant. Wanting to get back into them all but night classes don't really work well for me. It occurred to me last night (and I got so excited about it I couldn't sleep) it might be possible to start a local "mixed language practice group" where everyone has at least one language they'd like to practice, everyone brings something to the table and everyone gets to take something away. Everyone gets to be both student and teacher. I'm going to dig down into the idea some more at least.

One of my daughter's University Lecturers was a Japanese guy (called Seshi - or something like that?), he was a Maths professor. He spoke Japanese, English (both fairly obvious), Greek, Ancient Greek (learnt solely so he could read the original Iliad story), Spanish, Italian, German, French, Russian - plus various others.

As a University Professor he had a number of months holiday in the summer every year, and would go to a different country and learn the language while he was there. There are close similarities between various groups of languages, and he certainly had a knack for learning them.

 

[Nigel Goodwin]

As an adult I went to night school to learn Spanish so I could communicate with my Spanish wife's parents. On day one everyone else was fluent in Spanish except me. They all went there to meet Spanish people, not to learn Spanish.

My daughter went to night school in the Netherlands to learn Dutch - a MAJOR requirement, as she lives in the Netherlands in an area where hardly anyone in the general population speaks English. It wasn't a problem at work, as she worked at a University, and EVERYONE spoke English, and even lectures are in English.

Anyway, first day at the classes - and the teachers asked everyone what languages they already spoke, everyone spoke at least three or four, including Russian, and various Indian sub-continent languages - with the exception of my daughter, who only spoke English But at least all the class spoke English (even if it might be their third of fourth language), so the class was taught Dutch using English as the default language.

Did you ever manage to learn Spanish AG, my daughter actually did Spanish at school, but never to any great degree.

 

[audioguru]

My wife took our kids to Spain and they learned Spanish but I stayed home to work and take care of our dog. I rarely saw the in-laws in a different part of Canada. Therefore I speaky zee no Spanish.
Our son married a Mexican woman who barely speaks English and their kids do not speak Spanish. Their wedding in Mexico was lavish and many people there speak English.

 

[Nigel Goodwin]

My wife took our kids to Spain and they learned Spanish but I stayed home to work and take care of our dog. I rarely saw the in-laws in a different part of Canada. Therefore I speaky zee no Spanish.
Our son married a Mexican woman who barely speaks English and their kids do not speak Spanish. Their wedding in Mexico was lavish and many people there speak English.

I'm pleased to see the Canadians are maintaining the long English tradition of not learning any foreign languages

On the complete opposite to us, a friend's brother lives in Germany, and his young son (who unfortunately has Leukaemia, and has spent much of his young life in a plastic bubble) speaks excellent German, English and Spanish - as his close family are all from different countries, and he learnt to speak all three naturally as children do.