Borbely Fet Follower / HarryHaller?

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Fred, can you confirm that the circuit I posted is the one you used? I'd like to try a buffer as shown using a 2sk389 (Borbely mentions very low offset with the dual fet), and DC couple it if possible. I'll be using dual supplys. What do you think would be the effect of dropping the supplies to +/-15v?

Thanks,
RonS
 
To jewilson

We all try some simple and new circuits as sparrow nest and it is normal. But I mean, that this nests don't " learn " anybody. To get this into the transparent box and send photo by internet to the all world is for me little bit perverse. I like very much precision work and don't understand somethig like this. I can't talk about this more - somebody understand to me, somebody don't. Don't take this like my " promotion ", I was meaned this really honest and don't need to do myself visible thrue criticism of bad work of others.
 
diyAudio Retiree
Joined 2002
Last but not least

"little bit perverse"

Only a little.................. now you are hurting my feelings!


Name that Pig farmer:

Entry 3 from a commercial product ........

"Form follows function" - Louis Sullivan, mentor of Frank Lloyd Wright

PS

This all in fun as I have the greatest respect for my fellow farmers.
I also send out my thanks to the pig farmer's daughter who tutored me in college physics (while wearing overalls) at the University of Arkansas.

Thanks Ramona...... wherever you are! If you had only unbraided your hair and worn a dress a couple of times, I would have asked you out. I think there might have been cute girl behind that disguise, and there is nothing sexier than a very intelligent woman.
 

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Ah, Fred,

Truly a delight to see your gracile, talkative form returning to our SS gossip center........

Breadboarding. For God's sake, this is the first stage, proof of concept, just trying to figure out if it will work.... Of course it will be a mess! By definition!

We all love a precision, elegant pcb, but I find an initial circuit mockup takes about an hour, it's quick. The careful design of a production pcb might take me a whole week of grinding hard work, and I sure as hell won't go through the process if I know it won't work!

You gotta start somewhere! We're all impatient to see if it works, if it does, we then refine it to a pcb. That's logical!

Elso, unfortunately I can't reveal Fred's I/V (which we did together, in fact), but I can say it's a folded cascode with a virtual ground current input. That should do it! It forms a part of my company's latest product, a kitset DAC, which uses FIFO reclocking. It's proving to be a huge project, with a pcb approaching 200 x 260mm.

Cheers,

Hugh
 
diyAudio Retiree
Joined 2002
Help John!

transducer said:
Fred, can you confirm that the circuit I posted is the one you used? I'd like to try a buffer as shown using a 2sk389 (Borbely mentions very low offset with the dual fet), and DC couple it if possible. I'll be using dual supplys. What do you think would be the effect of dropping the supplies to +/-15v?

Thanks,
RonS

I don't like to run the Toshiba fets over 15 volts drain to source for noise considerations. I don't think you can use the two transistors in the 2SK389 for the circuit since they are fabbed on the same sustrate. Mr. Curl, can you tell us if this assumption is correct?
 
Fred, quoting from Erno's article: "If the two JFETs are matched and the two source resistors are equal, then the DC offset will be very small. With two matched K170BLs, I measured less than 1mV offset. (It would probably be even lower if you used here a dual monolithic JFET like the K389BL/V.)" Seems like Erno is recommending the K389, but he may not have taken into account your point about common substrate. Hopefully John will chime in here, as I have a pile of K389s :) but no K170s to play with.

Regards,
RonS
 
Fighting over words

Why does so many threads contains more fighting over words that on the actual subject????
We all have different opinions, - otherwise this splendid forum wouldn't exist.........!
Another thing is the language. Not all members have had the opportunity to learn English in school, and they may be using bad or improper words to express their feelings etc.
How about discussing electronic instead :yes:
Or lets us all go for a beer :D
 
Disabled Account
Joined 2003
Re: Fighting over words

ACD said:
Why does so many threads contains more fighting over words that on the actual subject????


my guess is that some of us feel the need to express themselves in a "sophisticated" manner by writting convoluted English.

Rather than making themself to be understood, they chose to be non-understandble so people cannot figure out how much / little they know.

superficial if you ask me.
 
I also think we must be a bit careful with interpretation of what is
written by non-native speakers. Upupa Epops is clearly not a native
speaker, so we cannot be sure what he meant by the phrase "pigs
work". I am not a native speaker either and don't know how
to properly interpret that phrase in english. I can imagine several
possible meanings, and the one I guessed on seem not to concur
with how most others interpreted it. Probably my guess was wrong,
but does that mean Upopa Epops used it in the right way? Perhaps
he should try to rephrase his statement and explain what he meant,
or perhaps even better, let us just drop the subject.

Adding to that, I am often surprised at how bad some native
speakers write english, but then I realize that in all fairness,
a lot of swedes are also very bad at using their own native
language in writing when reading swedish forums for instance.
I think, however, that is forum has a very high tolerance to
spelling errors and grammatical errors. It is rather seldom that
people complain about others bad language, but rather very
patiently try to understand what people might actually mean.
 
Fred

Entry number 2 below in the
guess the pig farmer contest ..........

Nelson Pass A40, I looked all over for my copy, could not find it.

Entry number 3 below in the contest....

Maybe the work of the John Curl, or Batman.. not sure.

Christer,
We have a saying, a pig is a pig no matter what name you call it. and your english is very good.

Hugh,
Your right on target why spend the time and effort to build a prototype and spend alot of effort when you know you'll be changing it.

Also, I find it amazing that Fred did such a nice job. Most engineers I know can even hold a soldering iron. It's only us analog guys that do......




:)
 
jewilson said:

Christer,
We have a saying, a pig is a pig no matter what name you call it. and your english is very good.

Yes, well my, probably false, reading of the phrase "pigs work" was
rather that it would be awkward or a lot of work to do, not saying
anything about the result or the designer. However, I also realized
that interpretation seemed somewhat strange in the context. Anyway,
the point was that it is not obvious that non-native speakers use
or understand a phrase in the same way as a native speaker, or
other non-natives either.

BTW, thanks for the compliment.
 
Why don't some of you try to understand the circuits, before you start ranting and raving? Borbeley did good research on followers. His "White follower" comes from a MIT publication written on tube circuits developed in WW2. The White follower uses a .22uf (or so) cap to turn the normal current source load into an active common source amplifier. This gives push pull operation and improved current drive, because the current source tends to turn off when the normal follower fet is driving the load with current.
In my opinion, this overcomplicates the usual requirements for a follower, and I prefer a follower without the added .22uf cap. However, in some cases, this could be a useful addition.
For most amateurs, and me as well, the simple 2SK389 slightly biased off from Idss by two 10 ohm resistors, running at +/- 18V, works darn well with loads over 5K. Higher supply voltages could cause problems with leakage or breakdown, yet could be used with selected devices, but not by amateurs without a curve tracer to select out high voltage parts.
 
OK guys

As " pigs work " is in our country described work, which is not pretty, is untidy and disorganized. Can somebody to tell me, which word in english is right for this case - I have any slang dictionary. My english is not " queen english ", I know, but I understand relatively wery well when talk every " nonamericans " - americans have for me many slangs words and many puns. In the next time I will ask PMA, he knows language much better than I know. I have only one question to Fred : why are you soldering with silver ? Silver is " astral " metal ( bullets against vampires was maded silver ) or are you developed " space products " ?
 
Upupa Epops,

I have never used silver solder. Maybe I am just a non-believe because I have not used it and I have not seen the technical data to prove that it works any better. I have built circuits that work up in the Gig Hz range and systems that have SN 0f greater than 120db and we did not need silver solder to make it happen.

Upupa, what you said and the way you said it was very clear. A pig is sloppy unclean and it means a poorly done job it this context. I bet it has the same meaning where you are from. I just do not agree with your assessment of Fred’s work or that it merits that kind of comment.

John,
I believe he understands that silver a better conductor. Therefore, I believe he is asking why is lead based solder the standard and why should he switch. I have never seen any technical data relating to any imperial measurements that prove that silver solder is beneficial. In addition, I do not believe you can even find vapor deposit method or other ones that support silver solder in production method, unless it done by hand. Well I could be wrong Fred is the manufacturing engineer.
:)
 
diyAudio Senior Member
Joined 2002
LINGUISTS...

Hi,

It is rather seldom that
people complain about others bad language, but rather very
patiently try to understand what people might actually mean.

More commonly used is the phrase: It is rather rare.

I do understand the meaning of your post, though.:)

Question is, does anyone understand what this topic is about?

O.K., don't worry....I'll revert to my usual catatonic state of mind...

Nonetheless, the ability to speak and write a language correctly is frighteningly low nowadays...It scares the hell out of me.

Either way, if any of you need help to put things in more or less correct English, let me know.

I can help with Spanish, French, English, German and related languages in thema and translation.

If it helps communications, it should help social relations on the forum.

Cheers,;)
 
john curl said:

For most amateurs, and me as well, the simple 2SK389 slightly biased off from Idss by two 10 ohm resistors, running at +/- 18V, works darn well with loads over 5K. Higher supply voltages could cause problems with leakage or breakdown, yet could be used with selected devices, but not by amateurs without a curve tracer to select out high voltage parts.

John, I'm just a lowly amateur, trying to build a simple buffer for my passive volume control. The white follower appeals to me because I have a bunch of k389s. I've also got a few 2sj109s. So I could either build the white follower, or this one which is credited to you by Erno. If I built your follower, I could use 1/2 of each device per channel, or just use 1/2 of each device, and leave the other half disconnected. Any problem in using the k389 for the white follower, in regards to being on the same substrate?

Thanks,
RonS
 

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Ron S,

If you got the parts you should go ahead and build it. If you use a socket and you can switch the parts out later if you don't like the way it sounds or tests.

You know, some people won't use dual opamps that are in the same package, it's the same kind of deal. While I try to stay clear of doing that manufactures do it all the time. :)
 
It is best to use the White follower or even the simpler all N channel follower also described by Borbely. The same substrate is best. Just use a 389. The complementary follower will give you significant DC offset.
If you can, you should use SN 62 silver solder, which is what the real pros use. It melts at lower temperature than normal solder and will not make bad solder joints. It also sounds better.
 
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