Hi,
most reversed Emitter Base-Junctions i know, are used as Noise-Sources.
For example here:
http://sound.westhost.com/project11.htm
There should be a better solution.
Onra
most reversed Emitter Base-Junctions i know, are used as Noise-Sources.
For example here:
http://sound.westhost.com/project11.htm
There should be a better solution.
Onra
While I thought in the current source… direction, , leds, etc… and… a fet current source… I had an idea 
...probably not the best circuit... 
... but a simple and attractive solution.
Resistor R20 can be replaced by the transistor compound as shown in a preceding post.
...probably not the best circuit... ... but a simple and attractive solution.Resistor R20 can be replaced by the transistor compound as shown in a preceding post.
An externally hosted image should be here but it was not working when we last tested it.
An interesting method of grading zeners for noise, that I have used for years, is to monitor the noise across the devices with a scope while using my HP bench supply to bias them. The noise spectrum changes quite dramatically as you come into breakdown and then drops to it's minimum at it's prefered current flow. I note the current and voltage after it has settled down. I choose the ones to use by voltage match and bias them accordingly.
One other trick, if you want to know how quiet your supply is, choose a suitible coupling cap and hook the output of it up to a line input on your preamp and listen to it. Try this with and without a load and during normal operation of the supply. A good supply is dead quiet.
Mike
One other trick, if you want to know how quiet your supply is, choose a suitible coupling cap and hook the output of it up to a line input on your preamp and listen to it. Try this with and without a load and during normal operation of the supply. A good supply is dead quiet.
Mike
Hi, John, Hi, Guys
Now the V type Jfets are a pretty rare beasts... And for 2SJ72/73, IMO, you are the only one to have a stock of V parts I know of... Even Erno Borbely doesn't have anymore (his advertisment is wrong), and Chinese ones are just fakes... So...
Please let us (me?) know what are your own "statistics" on these parts sorting ? (a V 2SJ72 can be 10... 12 mA Idss and a V 2SK147 16...18 mA Idss). In my experience "high" BL type often overlap "low" V complementary type, and so, hyper rare "V type" is perhaps NOT the best choice for us, as real amateurs....
Bob (Crump) said me that your Vendetta Jfets were miraculously preserved from your home destruction by the gigantic forest fire in 1991 (where you also lost master tapes, and a lot of valuable things... I am really sorry for !) in Oakland because they were in a garage... So, my other question is : are they still in the garage ?... Mine are !
LOL !
Jbaudiophile
Now the V type Jfets are a pretty rare beasts... And for 2SJ72/73, IMO, you are the only one to have a stock of V parts I know of... Even Erno Borbely doesn't have anymore (his advertisment is wrong), and Chinese ones are just fakes... So...
Please let us (me?) know what are your own "statistics" on these parts sorting ? (a V 2SJ72 can be 10... 12 mA Idss and a V 2SK147 16...18 mA Idss). In my experience "high" BL type often overlap "low" V complementary type, and so, hyper rare "V type" is perhaps NOT the best choice for us, as real amateurs....
Bob (Crump) said me that your Vendetta Jfets were miraculously preserved from your home destruction by the gigantic forest fire in 1991 (where you also lost master tapes, and a lot of valuable things... I am really sorry for !) in Oakland because they were in a garage... So, my other question is : are they still in the garage ?... Mine are !
LOL !
Jbaudiophile
JBAUDIOPHILE
---But what where some guys just doing excepting criticize others, eh Forrr ?---
Are you feeling uneasy with my person ?
I think my criticisms at the begining of this thread may have a little responsability for it turning from dull sonic claims to a technical discussion. And I feel my attitude is the contrary of destructive when I indicated Christer's thread about voltage references noise.
Having its name usurped by people who pretend that only sonic virtues count (without encountering concensus about one technology), audiophily needs a lot of criticisms by people who try to have a rigorous way of thinking towards the various aspects of audio. For years, these "critics" were not allowed to express their opinions in specialised audio magazines (we all know what kinds of countries are those where critics are mute). They can do it now on the internet, there is no reason why they should not profit from this opportunity. It is understandable that this puts some people, who use to live more with claims than with facts, in an uncomfortable situation.
~~~~~ Forr
§§§
---But what where some guys just doing excepting criticize others, eh Forrr ?---
Are you feeling uneasy with my person ?
I think my criticisms at the begining of this thread may have a little responsability for it turning from dull sonic claims to a technical discussion. And I feel my attitude is the contrary of destructive when I indicated Christer's thread about voltage references noise.
Having its name usurped by people who pretend that only sonic virtues count (without encountering concensus about one technology), audiophily needs a lot of criticisms by people who try to have a rigorous way of thinking towards the various aspects of audio. For years, these "critics" were not allowed to express their opinions in specialised audio magazines (we all know what kinds of countries are those where critics are mute). They can do it now on the internet, there is no reason why they should not profit from this opportunity. It is understandable that this puts some people, who use to live more with claims than with facts, in an uncomfortable situation.
~~~~~ Forr
§§§
Yesand No, Forr,
I feel that you are at too much a distance frome me that I prefer not to discuss any point with you... Simple to hear, bo ? And yes,I feel tha you are already uninterested in DIYourself threads, but much more in your own "masters degree'" threads... So, I leave you with others on the same degree, as for me you are the perfect... complete with your prefered one..
And if you clamin' that you can see beyond the horizon, just don't bother me much that other guys that claim to be able to hear well under 10 Khz... But he expalined us that he wasn't able to do that.. And NOW you will PERHAPS understand that realfriends And thet are FRIENDS and I trust them miuch more that yoyu ever be... I hope that I am clear with it, For... Just stay with you OWN convictions WELL AHEAD OF ME,as apparently you claim you are... Will push you whren the time beeing... For the moment, I m conccnetrrating on much more interesting things and guys that you are ... (Just my opinion) Sttill to see what you produced from YOUR OWN as an amateur...
I DON'T think that you are an amateur, but rather an electronics teacher or someone having access to theories data... Not the guy I want to cross the please excuuse me... My own brother is an eletronics technician too, and I hadn't made any audio projectwith him for DECADES. Acadeiuc thinking is oin thing, but trying to obsfurcate another guys with that is another one... Just keep you ceramics in a place and judge that oth Curl, me asd some otherts are just rubbish... I REALLY din't care...
End of rent... And yeah... I am far too morron for you, as per your standads !!
Thre point is now closed for me... Won't answer ANY of your futher points... Simpluy NOT intrerested in what you have to say (prove ? Still to hear from your OWN designs... )
Plezase don't bothr me anymore... For that, I have some friends.. They are well known... and usually right, even if we disagree.. But they PROVE it to me... What you didn't make at any tiime....
Jbaudiophile
I feel that you are at too much a distance frome me that I prefer not to discuss any point with you... Simple to hear, bo ? And yes,I feel tha you are already uninterested in DIYourself threads, but much more in your own "masters degree'" threads... So, I leave you with others on the same degree, as for me you are the perfect... complete with your prefered one..
And if you clamin' that you can see beyond the horizon, just don't bother me much that other guys that claim to be able to hear well under 10 Khz... But he expalined us that he wasn't able to do that.. And NOW you will PERHAPS understand that realfriends And thet are FRIENDS and I trust them miuch more that yoyu ever be... I hope that I am clear with it, For... Just stay with you OWN convictions WELL AHEAD OF ME,as apparently you claim you are... Will push you whren the time beeing... For the moment, I m conccnetrrating on much more interesting things and guys that you are ... (Just my opinion) Sttill to see what you produced from YOUR OWN as an amateur...
I DON'T think that you are an amateur, but rather an electronics teacher or someone having access to theories data... Not the guy I want to cross the please excuuse me... My own brother is an eletronics technician too, and I hadn't made any audio projectwith him for DECADES. Acadeiuc thinking is oin thing, but trying to obsfurcate another guys with that is another one... Just keep you ceramics in a place and judge that oth Curl, me asd some otherts are just rubbish... I REALLY din't care...
End of rent... And yeah... I am far too morron for you, as per your standads !!
Thre point is now closed for me... Won't answer ANY of your futher points... Simpluy NOT intrerested in what you have to say (prove ? Still to hear from your OWN designs... )
Plezase don't bothr me anymore... For that, I have some friends.. They are well known... and usually right, even if we disagree.. But they PROVE it to me... What you didn't make at any tiime....
Jbaudiophile
Sorry Forr (he !!! Just LOL !!!). The message was cut in the middle by the computer (seems to me that I amf ar too slow to answer... I am sure that you agree, eh ?)., and I wouldn't be that imolite with you...
Suffivce to say hat I am happy with some other threads and that yours are NOT interesting ones to me... Not because your academic level 'still sorry forr... Oh ! I diud it again ! OOPsps...), but because you don't seem to be able to see beyond the horizon you claim to do...
And yes, I feel uncomfortable with your threads... Now it is said... NOT because I won't dissuss the point with you, but because you will use over-heard points I have my ow papers stock.. You asked me with Elso how to alter or "have correct" the audio spectrum distribution... With fundamntals and harmonics put right (ahem, almost...)...
Don't have your academics the answer ? No?
Very sorry Forr...
Try again... and read more !
Jbaudiophile
Suffivce to say hat I am happy with some other threads and that yours are NOT interesting ones to me... Not because your academic level 'still sorry forr... Oh ! I diud it again ! OOPsps...), but because you don't seem to be able to see beyond the horizon you claim to do...
And yes, I feel uncomfortable with your threads... Now it is said... NOT because I won't dissuss the point with you, but because you will use over-heard points I have my ow papers stock.. You asked me with Elso how to alter or "have correct" the audio spectrum distribution... With fundamntals and harmonics put right (ahem, almost...)...
Don't have your academics the answer ? No?
Very sorry Forr...
Try again... and read more !
Jbaudiophile
JBAUDIOPHILE
You're nearly angry, now, which means more uneasy with yourself than with me... keep calm.
May I assure you : I am a DIYer. Before having studied theories which are entirely verified when practising, I read (and sometimes tried to apply, what lost time !) a huge number of extravagant audio receipes claimed by auto-authorised audio-gurus. With them, too many people have gone nowhere.
Having a well established theorical background allows to get a practical result in the shortest delay, diminishing the experimental and tuning time. Do not attend that "critics" keep silent towards the common fallacies which have spoiled audiophily.
~~~~~~ Forr
§§§
You're nearly angry, now, which means more uneasy with yourself than with me... keep calm.
May I assure you : I am a DIYer. Before having studied theories which are entirely verified when practising, I read (and sometimes tried to apply, what lost time !) a huge number of extravagant audio receipes claimed by auto-authorised audio-gurus. With them, too many people have gone nowhere.
Having a well established theorical background allows to get a practical result in the shortest delay, diminishing the experimental and tuning time. Do not attend that "critics" keep silent towards the common fallacies which have spoiled audiophily.
~~~~~~ Forr
§§§
JOHN CURL
---What are you two fighting about?---
I may have upset JBAudiophile in a previous thread, about a month ago. It was about the spectral content of harmonic distorsion.
JBAUDIOPHILE
---Zener diode can be done withn reverse polarized bipolar transistor.... Just have a look on this wonderful amp... Doidn't try this ? But what where some guys just doing excepting criticize others, eh Forrr ?---
Did I write anything against reverse biased bipolars used as zeners anywhere ? No. I am just supposed to have prejudices against. I saw Norman Thagart using them. In fact, I did not what to think about them until the most wellcome recent threads about constant current sources.
~~~~~~ Forr
§§§
---What are you two fighting about?---
I may have upset JBAudiophile in a previous thread, about a month ago. It was about the spectral content of harmonic distorsion.
JBAUDIOPHILE
---Zener diode can be done withn reverse polarized bipolar transistor.... Just have a look on this wonderful amp... Doidn't try this ? But what where some guys just doing excepting criticize others, eh Forrr ?---
Did I write anything against reverse biased bipolars used as zeners anywhere ? No. I am just supposed to have prejudices against. I saw Norman Thagart using them. In fact, I did not what to think about them until the most wellcome recent threads about constant current sources.
~~~~~~ Forr
§§§
For the record, reversed biased transistors have been used as 'zener' diodes since the first analog IC op amps were designed. It is a convenience, because additional processing steps do not have to be done, in order to create a 'zener' reference. This goes back about 40 years.
Now what we have established here, as far as I can tell, is that leds are probably the best way to reference a current source, unless you have a current limitiation, and this is where some special low voltage zeners, operating at 250 ua seem to be OK, except they will be fairly high impedance at their operating point, and therefore useless in our present current source examples.
I wish to point out that zeners are invariably rated at micovolts/ rt Hz, especially above 5V. To convert to rt/Hz, just divide Christer's measurements by 144, (I am guessing here, but that is the sq rt of 20KHz) Even 1uV/rt Hz is REALLY noisy. Most IC op amps work 100-1000 times quieter than this. My original Levinson JC-1, Sota headamp, and the Vendetta phono amp are rated at 0.4nV/rt Hz. This is 2500 times lower than a good zener. This is why I used a Norton equivalent of a zener instead. There I have a low Gm, low noise fet, like a J203, as the reference, with its noise attenuated by a large (100uf) cap to ground. It is true that there will still be some really low 1/f noise, but it works well in the audio range.
Now what we have established here, as far as I can tell, is that leds are probably the best way to reference a current source, unless you have a current limitiation, and this is where some special low voltage zeners, operating at 250 ua seem to be OK, except they will be fairly high impedance at their operating point, and therefore useless in our present current source examples.
I wish to point out that zeners are invariably rated at micovolts/ rt Hz, especially above 5V. To convert to rt/Hz, just divide Christer's measurements by 144, (I am guessing here, but that is the sq rt of 20KHz) Even 1uV/rt Hz is REALLY noisy. Most IC op amps work 100-1000 times quieter than this. My original Levinson JC-1, Sota headamp, and the Vendetta phono amp are rated at 0.4nV/rt Hz. This is 2500 times lower than a good zener. This is why I used a Norton equivalent of a zener instead. There I have a low Gm, low noise fet, like a J203, as the reference, with its noise attenuated by a large (100uf) cap to ground. It is true that there will still be some really low 1/f noise, but it works well in the audio range.
Jbaudiophile and Forr, please behave like grownup people and quit arguing. You can continue per PM if you both wish but don't bother other members with your quarreling.
I also suggest to read the stuff you're going to post before pushing that "submit reply" button. Gosh, I was thinking I was using Babelfish for a moment.
John, can you measure Leds noise with your Quan-Tech measurement set? I tried this w.e. but I was not able to get any decent results (LT 1028 10R-1k, 10 kHz bandwidth), however with zeners, even below 5 volts, I easily could, it was a very “messy” test rig (solderless testboard) and it’s why I didn’t report here the results with the impedance values.
Do you think it’s a good idea to use the current source available at the adjust pin of the LM317 as I thought in using it for an “elegant” and useful design in Post #649 (without C30 capacitor!).
... Jean Paul
.
Do you think it’s a good idea to use the current source available at the adjust pin of the LM317 as I thought in using it for an “elegant” and useful design in Post #649 (without C30 capacitor!).
... Jean Paul
.
Hi JOHN CURL
Thanks for this documentation about reverse biased transistors. I believe that, when in series with a directly biased Si diode, or a transistor connected as a diode, they can make thermally stable references.
JEAN-PAUL
Sorry, I have been treated negatively twice in a first post, and even more in the following ones, that I could'nt stay without some replies (maybe crude, but polite) . I think any other DiyAudio "critic" mentionned would have react in a somewhat similar manner.
~~~~~ Forr
§§§
Thanks for this documentation about reverse biased transistors. I believe that, when in series with a directly biased Si diode, or a transistor connected as a diode, they can make thermally stable references.
JEAN-PAUL
Sorry, I have been treated negatively twice in a first post, and even more in the following ones, that I could'nt stay without some replies (maybe crude, but polite) . I think any other DiyAudio "critic" mentionned would have react in a somewhat similar manner.
~~~~~ Forr
§§§
Richard, I could use the Quantech, but it would not be more accurate than Christer's set-up. It would give spot noise values at specific frequencies that might be helpful, but I doubt it.
Forr and jbaudiophile, let's not get off track, if possible. Actually, I like learning from Christer's measurements. He has been fairly thorough.
Forr and jbaudiophile, let's not get off track, if possible. Actually, I like learning from Christer's measurements. He has been fairly thorough.
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